손실함수를 활용한 Grey Relational Analysis 기반 다특성 공정의 최적화

최이찬 창원대학교 2019 국내석사

Multi-characteristic optimization problem is frequently confronted in modern industries due to the customer’s various requirements on the products and services. Because of multi-characteristics’ interrelation, however, it is not easy to satisfy them all at the same time. There are several approaches developed to solve this problem and Grey relational analysis is among them. Grey relational analysis method transforms, like the other optimization methods for multi-characteristic situation, the influences of factors on multiple characteristics into the same scaled measures. And then it optimizes the objective function of univariate characteristic derived from multiple characteristics interrelations. In the Grey relational analysis procedure, the compatibility sequence is usually obtained as the linear function of the distance between the value of quality characteristic and its target. As is known Taguchi’s quadratic loss, the quality loss increases as the value of quality characteristic is getting off the target. And therefore, it can be applied to obtain the comparability sequence of Grey relational analysis. In this thesis, the optimization of multi-characteristic process based on Grey relational analysis using Taguchi’s quadratic loss function is considered. And the case study of the grinding process of aircraft engine bushing is given to show the efficiency of newly proposed Grey relational analysis for optimizing multi-characteristic process. The results of process capability analyses for both Grey relational analyses are compared and the newly proposed Grey relational method can be efficient for certain situations.

Optimization of Micro-WEDM Parameters for Titanium Alloy using Grey Relational Analysis : Grey relational analysis를 이용한 티타늄 합금 가공의 마이크로-WEDM 변수 최적화

Thamizhmani, G 경북대학교 대학원 2012 국내석사

In recent years, numerous developments in EDM (Electrical discharge machining) have focused on the production of micro-features with enhanced machined surface quality. Micro-WEDM process is an appropriate machining method for manufacturing accurate, hard and complex 3D micro features. It has become an important non-traditional advanced machining process, as it provides an effective solution for producing components from difficult-to-cut materials like titanium alloys. Titanium alloys have found very wide application in aerospace industry, automotive, medicine and dentistry which require great reliability due to their excellent corrosion resistance, high strength-to-weight ratio, high temperature stability and mechanical properties. However the main difficulties in machining them are high cutting temperatures and rapid tool wear. Since micro-WEDM is a very complex thermo-electrical process involving different process parameters, thus the selection of optimum process parameter to obtain higher material removal rate (MRR), lower surface roughness (SR) and lesser overcut (OC) is a challenging task. In this research, optimization of micro-WEDM parameters has been found out for optimal machining of titanium alloy (Ti-6Al-4V) using grey relational analysis (GRA). The process parameters selected for optimization are gap voltage, capacitance and wire feed rate to achieve multi-objective performance characteristics such as material removal rate, surface roughness and overcut. The experiments designed by using Taguchi orthogonal array were conducted on titanium alloy in micro-WEDM. After analyzing the experimental results, the optimal process parameter has been determined by using grey relational analysis and the relatively significant parameter has been identified by using analysis of variance. The optimized process parameter has been verified by conducting the confirmation experiment. 본 연구는 마이크로 WEDM을 사용한 티타늄 합금(Ti-6Al-4V) 가공에서 가공품의 품질을 향상시키기 위해 grey relational analysis를 이용하여 최적 가공조건을 도출한다. 가공 변수는 제어 가능한 인자인 간극 전압, 정전 용량 및 와이어 공급 속도이며, 가공품의 품질은 재료재거율(MRR), 표면거칠기 및 오버 컷의 가공 특성치를 동시에 고려하여 평가한다. 실험은 다구찌 직교 행렬 실험법으로 실시하였으며, 최적 가공 조건은 grey relational analysis로 도출하였다. 최종적으로 가공품의 품질에 가장 큰 영향을 나타내는 매개 변수는 ANOVA를 통해 정전 용량으로 확인하였다. 선정한 최적가공 조건의 타당성은 실험을 통하여 검증하였다.

Analysis of Factors Influencing Real Estate Prices in China based on the use of GRA and VAR

펑텅롱 호서대학교 대학원 2022 국내박사

The high real estate price in China is an issue subject to heated debates. This issue not only concerns the well being of the Chinese people in general, but also relates closely to the Chinese national economic development. The current real estate prices in first and second-tier cities in China are excessively high, which do not match the local residents’ income level. They reduce their happiness and sense of belonging to the city. As a result, people living in such cities prefer to spend their money buying real estates in third or fourth-tier cities instead, causing a sharp increase in the price of these cities as well. Faced with this dilemma, the state government has introduced a series of regulatory policies amid the restraint of these price hikes in all cities and the stabilization of the real estate market, only to find unsatisfactory effect. As such, we find it necessary to explore the root cause underlying the continuously rising real estate prices, search for influencing factors that are truly valid, and provide a more realistic and theoretical basis on which the state government can introduce more effective regulatory policies in the regard in the future. Based on the research already done by the domestic and international scholars regarding the influencing factors of the real estate price, this paper selects data pertaining to the real estate market in China drawn in 2002 through 2019. Upon considering the validity of such data, we use them to analyze the developmental status of the real estate market in China. Then, we select certain influencing factors to perform qualitative and quantitative analysis. These factors include the price’s self-factors, economic factors, financial factors, and residents’ living standard factors. Finally, we give a forecast to the future real estate prices in China. In terms of the methods we use for producing the results of our research, first of all, we adopt the Gray correlation analysis to quantitatively explore the relative importance of these factors to the real estate price. Our research discovers that factors of money supply M2, balance of deposits made into various financial institutions, investment completed in real estate development, medium and long-term loan interest rates, and GDP all have a relatively high degree of Gray correlation with the real estate price. Secondly, we select highly correlated influential factors using which to construct the vector autoregressive model VAR, and subsequently study the dynamic impacts that these factors have on the real estate price. Our respective study shows that money supply has a short-term impact on the real estate price. It impacts the price positively at first, and negatively later on. The positive and negative impacts alter cyclically. As for the balance of deposits made into financial institutions, it has a high positive effect on the current price, but a negative effect on the overall price in the long run. When it comes to the investment completed in real estate development, it has a positive influence on the overall real estate price. The current real estate price does not respond quickly to a change in medium and long-term loan interest rates, but is impacted positively by it later on. GDP positively impacts the real estate price during its first three stages, after which this impact declines slightly. Over time, this declining trend weakens gradually, and approaches stability at last. As for the factor of GDP, it impacts the real estate price positively in general.

한중 국경 간 전자상거래 발전 수준이 한국의 대중 수출에 미치는 영향에 관한 연구

장기봉 우석대학교 일반대학원 2021 국내박사

The global economy, which had not completely escaped the swamp of the global economic downturn in 2008, suffered a severe slump in the global economy and trade scale due to the 2020 coronavirus crisis. Despite the global economic downturn, the growing e-commerce experience has become a new growth paradigm for the global economy as a new business process. In addition, Korea and China are at the top of the world economy, and the e-commerce economic activities of the two countries are expected to be the key to enhancing the economic growth of both countries with innovative capabilities. According to the Korea National Statistical Office, the amount of online overseas direct purchases in 2019 was KRW 3,635.5 billion, an increase of 22.3% from the previous year, and the amount of online overseas direct sales was KRW 5,960 billion, an increase of 65.4% from the previous year. Of these, China's e-commerce exports increased by 78.9% compared to the previous year, so China has expanded to the country with the largest proportion of Korean online e-commerce exports. Meanwhile, according to the "2019 China e-commerce report", the total import and export of cross-border e-commerce in China in 2019 was 186.2 billion yuan, an increase of 38.3% over the same period last year, and imports of the same amount were 91.1 billion yuan, an annual average growth of 27.4%. It showed off the world's largest e-commerce market size and showed a rapid growth trend, therefore, the improvement of the development level of e-commerce between Korea and China is expected to revitalize trade exchanges between Korea and China and have a positive impact on the economic growth of Korea. Recently, as interest in cross-border e-commerce has increased, some statistical data has been released. However, systematic statistical data on cross-border e-commerce between Korea and China has not yet been prepared. Therefore, in order to measure the development level of e-commerce between Korea and China from 2014 to 2019, the determinants of the development level of e-commerce between Korea and China were first analyzed by statistical analysis and acceptance analysis. Build. In addition, control variables such as GDP, population, distance, tariff level, and boundary are added, and factor analysis and structural equation motel analysis are performed through regression analysis using a fixed effect method.

Research on Factors Affecting Tourism Income and Tourism Cooperation Strategy between Korea and China

이화중 우석대학교 대학원 2020 국내박사

Modern tourism business started from the 19th century and developed greatly in the 20th century. Nowadays the international tourism has become one of the biggest industry in the world since 1990s. The world tourism market has become an international common market including Europe, America, Asian-Pacific region, Africa, Middle East and South Asia since 1990s. On September 13th 2017, the secretary of the UNWTO Taleb Rifay announced that Asian tourism industry increased impressively with an annual growth rate of 3% to 4% exceeding the world average level. It was regarded that Asia might become the “engine” of the world tourism industry. Korea and China are two of important economic components in the Asia-Pacific region. Korea is one of the developed countries with systematic tourism strategy in the world. However China has been the biggest developing nation in Asia for years with fast growing tourism demands based on its rich tourism resources and vast land scape. Although there are significant differences both in economy and tourism industry, there are great demand for the cooperation between the two nations due to the correlations of their economic, cultural and geographical features correspondingly. The great achievements of Asian tourism market may achieved by cooperation between Korea and China. The thesis applied the BP Neural Network Method and Grey Relational Analysis to analyze the tourism market in Korea and China. The first objective of the thesis is to investigate the tourism industry both in Korea and China. The second objective is to analyze the affecting factors of tourism income and identify the key items. The third objective is to explore the possibilities and the dynamic strategies of tourism cooperation between Korea and China. Findings 1: From the results in BP Neural Network analysis, the tourism market in Korea has shown a slowdown trend in growth after 2005 while China’s tourism extends rapidly. The factors affecting domestic tourism income of Korea and China are analyzed by the Grey Relational Analysis method. The indicators network contains 8 primary indicators (tourism status, economic support, transport network, passenger transported, tourism services, investment, social civilization and natural environment) with 19 secondary indicators. The factors affecting international tourism income of Korea and China are examined either by the Grey Relational Analysis method. The indicators network contains 9 primary indicators (tourism status, economic support, transport network , passenger transported, tourism services, investment, social civilization, natural environment and foreign exchange) with 21 secondary indicators. Findings 2: There are 4 strong factors affecting the Korean domestic tourism income as followed: the number of private cars, per capita expenditure of domestic tourists, the number of tourist companies and passenger turnover. Comparatively, there are 6 strong factors affecting Chinese domestic tourism income are the number of private cars, amount of domestic tourists, per capita GDP, total fixed investment, tourism enterprise practitioners, per capita disposable income. Findings 3: There are 4 strong factors affecting the Korean international tourism income as followed: the amount of inbound tourists, the amount of international students studying in Korea, the number of tourist companies and tourism enterprise practitioners. Comparatively, there are 10 strong factors affecting Chinese domestic tourism income are per capita expenditure of inbound tourists, total highway mileage, the amount of domestic university students, total railway mileage, passenger turnover, urban park area per capita, export amount, import amount, number of tourism companies and number of hotels. Conclusion 1: Under the rapid development of tourism in Asia-Pacific region, tourism industry of Korea and China is facing good opportunities, and the prospects for tourism development are bright Korea and China. Conclusion 2: There are significant differences and outcomes in the relationship of tourism income and the affecting factors both in Korea and China, due to their economic levels, social and cultural contexts, as well as to tourism resources, tourism market scales, services and so on. Overall, Korean tourism industry is more mature than that of China while Chinese tourism industry is developing faster currently than that of Korea. Finally, tourism cooperation is necessary and possible to develop tourism industry for Korea and China. While construct a multi-layer tourism cooperation network model would greatly support the development of tourism cooperation in Korea and China. 현대 관광산업은 19세기에 출현했고, 20세기에 큰 발전을 이루었다. 오늘날 국제관광은 1990년대 이후 세계에서 가장 큰 산업 중 하나가 되었다. 1990년대부터 세계 관광시장은 유럽, 미주, 아시아태평양지역, 아프리카, 중동, 남아시아가 공존하는 관광시장 구조체계를 형성해 왔다. 세계관광기구(WTO)의 보고서에 따르면 2005년~2015년 기간 세계 관광산업에서 아시아태평양 지역이 가장 빠르게 성장하는 지역으로 예측하고 있다. 2017년 9월 13일, 세계관광기구 제22차 총회에서 사무총장 탈렙 리파이는 아시아 관광산업이 세계 평균보다 3~4% 높은 연평균 성장률을 보이며 매우 인상적이라고 한 바 있으면 아시아는 세계 관광산업의 '중심축'이 될 것이라고 하였다. 한▪중 양국은 아시아태평양 경제의 중요한 구성 부분이다. 한국은 세계적으로 체계적인 관광 전략을 가진 선진국 중 하나이다. 중국은 풍부한 관광 자원과 방대한 토지를 바탕으로 빠르게 성장하는 관광 수요로 수년간 아시아에서 가장 큰 관광분야의 개발도상국이 되어 왔다. 경제와 관광산업의 발전 수준에서는 어느 정도 차이가 있지만 여전히 지리적으로 인접하고, 역사와 문화의 유사성, 경제적 상호 의존성에 의해 두 나라 사이의 협력을 위한 탄탄한 토대가 있어 왔다. 아시아 관광시장의 큰 업적은 한▪중 간 협력으로 이룰 수 있을 것이다. 본 논문에서는 BP 신경네트워크(BP Neural Network)와 회색관계분석 방법(Grey Relational Analysis)을 사용하여 한▪중 양국의 관광시장을 연구하였다. 첫째 연구 목표는 한▪중 양국의 관광산업을 분석하는 것이었고, 두 번째는 관광수입의 영향요인을 분석하고 주요 항목을 파악하는 것이었다. 그리고 세 번째 연구 목표는 한▪중 관광 협력의 가능성과 전략을 탐구하는 것이었다. 연구결과 첫째로 BP 신경분석 결과에 의하면, 한국의 관광 시장은 2005년 이후 성장이 둔화를 되었는데, 중국의 관광 시장은 급속히 확대되고 있었다. 한▪중 양국의 국내 관광수입 영향요인은 회색관계분석방법으로 분석해 보았다. 국내 지표체계는 8개의 1차 지표(관광상황, 경제적 지원, 교통상황, 여객운송량, 관광서비스, 투자상황, 사회문명, 자연환경)와 19개의 2차 지표를 포함한다. 한중 양국의 국제관광수입 영향요인도 회색 관련 분석법으로 살펴하였다. 국제 지표체계는 9개의 1차 지표(관광 상황, 경제적 지원, 교통상황, 여객 운송량, 관광서비스, 투자 상황, 사회문명, 자연환경, 대외교류)와 21개의 2차 지표를 포함하였다. 두 번째로 분석결과 한국의 국내 관광 수입에 영향을 미치는 4가지 주요 요인은 자가용 및 자동차 수, 국내 관광객 1인당 지출, 관광업체 수, 승객의 유동량이다. 중국의 국내 관광 수입에 영향을 미치는 요인은 자가용 자동차 수, 국내관광객 수, 1인당 GDP, 총 고정투자, 관광업체 수, 1인당 가처분소득 6가지 나타났다. 세 번째로, 한국의 국제 관광 수입에 영향을 미치는 4가지 주요 요인은 입국 관광객 수, 외국인 유학생 수, 관광업체 수, 관광기업 실무자 수 등이었다. 중국의 국제 관광 수입에 영향을 미치는 10가지 주요 요인은 입국 관광객 1인당 지출, 고속도로 마일리지, 대학생 수, 철도 마일리지, 여객 유동량, 1인당 도시공원 면적, 수출액, 수입액, 관광업체 수, 호텔 수 등이었다. 따라서 분 연구에 의한 결론은 첫째 아시아 태평양 지역의 관광 산업 급속한 발전의 배경 아래, 한▪중 관광 산업 발전은 좋은 기회에 직면해 있으며, 한▪중 관광 발전의 전망은 밝다. 두 번째 한▪중 관광수입과 영향요인의 관계는 큰 차이가 있다. 이러한 차이는 경제적 수준, 사회문화적 상황, 그리고 관광자원, 관광시장, 서비스 등의 차이로 초래된다. 전반적으로 한국 관광산업은 중국보다 성숙하고 중국 관광산업은 한국보다 빠르게 발전하고 있다 마지막으로, 관광 협력은 한▪중 양국 관광산업 잘 발전의 필요적 요인 이다. 다층 관광 협력 네트워크 모델을 구축하는 것은 한▪중 관광 협력 발전에 큰 도움이 될 수 있다.

Assessment of Agricultural Supply Chain Finance Model: Focus on Jilin Province China

Ju, Wen 강원대학교 대학원 2023 국내석사

현 단계에서 중국의 주요한 모순은 더 나은 삶에 대한 사람들의 열망 및 발전과 부족 사이의 불균형 사이의 모순으로 변화되였다. 현재 도시와 농촌의 큰 격차는 의심할 여지없이 중국의 주요한 모순으로 인해 가장 큰 타격을 받고 있다. 지난 20년 간의 중앙 1호 문서를 살펴보면 농촌 금융 부문의 개혁이 더욱 더 정부의 주요 계획의 대상이 되어왔다. 2017년 길림성은 농촌재정개혁 시범성으로 선정되어 국가농촌재정개혁 시범구의 기능을 수행하였다. 농촌금융의 효율적 발전은 농촌활성화 촉진에 근본적인 역할을 한다. 길림성의 토지자원, 농업 인프라, 농업 및 농촌고용자들은 상당한 비교우위를 가지고 있다. 길림성은 길림성 내 농촌 금융에 이용될 수 있도록 농업공급사슬금융 개발을 우선 순위를 두었다. 개발은 참조 및 평가 기준을 위한 매우 진보된 모델을 제공한다. 길림성 농업공급사슬금융 발전의 운영방식은 아직 탐색단계에 있지만 그 발전경험은 상대적으로 뚜렷한 대표적인 특징을 가지고 있다. 개발 유형은 중국 농업 공급사슬 금융의 개발에 중요한 의미를 갖는다. 본 논문의 구체적인 구성은 다음과 같다. 제1장은 서론으로 주로 길림성 농업 공급사슬 금융 효과의 평가 및 개발 모델 연구의 기초, 국내외 연구 상황, 주요 연구 내용, 연구 방법, 연구 혁신 포인트 및 연구 기술 경로를 설명한다. 제2장은 문헌 고찰과 이론적 근거이다. 농업공급사슬금융 등의 관련 문헌을 위주로 정리하고, 정보비대칭이론, 거래비용이론, 공급사슬관리 등의 기초이론을 해설한다. 제3장은 길림성 농업공급사슬금융의 개요이다. 길림성의 농업공급사슬금융의 주요 유형과 문제점 및 주요 원인을 소개한다. 제4장에서는 길림성 농업공급사슬금융의 주요 모델을 선정하고 길림성 농업공급사슬금융 주요 모델에 대한 실증 연구 모델을 구축한다. 제5장에서는 길림성 농업공급사슬금융의 주요 모델을 평가하고 데이터와 지표를 선정하여 계량경제모델을 사용하여 평가하고 실증분석결과를 제시한 다음 본 연구의 결론을 제시한다. 제6장에서는 길림성 농업공급사슬금융의 발전을 위한 건의를 제안하고 길림성 농업공급사슬금융의 건전하고 신속한 발전을 보장하기 위한 합리적인 발전 모델을 제시한다. 본 논문은 다음의 네 가지 결론을 도출한다. 첫째, 현재 길림성 농업공급사슬금융의 발전단계는 비교적 후진적이다. 비록 농업공급사슬금융의 서로 다른 발전 모델을 만들어냈지만 세 가지 발전 모델은 현재까지 이상향에 있어 큰 성과를 내지 못했으며, 길림성에서도 이를 이성적으로 인정해야 한다. 농업공급사슬금융의 개발 상태는 현실에서 출발하여서 길림성 농업 발전의 재정 병목 현상을 돌파해야 한다. 둘째, 농업핵심기업을 더 많이 육성하고 농업산업에서 농업핵심기업의 역할을 발휘 시키며 금융기관과 농업핵심기업의 합리적인 교량을 장려한다. 셋째, “농업, 농촌 지역과 농부들”의 발전에서 금융상품의 큰 역할을 충분히 인식하고 사고를 넓혀서 소유자들로부터 농업에서 금융수단을 올바르고 합리적으로 취급할 것을 요구해야 한다. 넷째, 길림성의 농업공급사슬금융의 문제점에 대해 다음과 같은 조치를 제안한다: 농업공급사슬금융 서비스의 능력 향상; 농업공급사슬에서 핵심 기업의 역할 강화; 농업공급사슬금융 시설의 건설에 적극적 참여; 농업공급사슬금융 서비스의 생태 건설 구축. The main contradiction in China at this stage has been transformed into the contradiction between the people's longing for a better life and the imbalance between development and insufficiency. At present, the huge gap between urban and rural development is undoubtedly the hardest hit by China's current major contradictions. Looking at the Central No. 1 document in the past two decades, the reform of the rural financial sector has increasingly become the target of the government's key layout. In 2017, Jilin Province was established as a pilot province for rural financial reform, carrying the function of the pilot zone of the national rural financial reform. The efficient development of rural finance plays a fundamental role in promoting rural revitalization. Jilin Province's land resources, agricultural infrastructure, and agricultural and rural employees have significant comparative advantages. Jilin Province gives priority to the development of agricultural supply chain finance, which can be used for rural finance in Jilin Province. Development provides an extremely advanced model for reference and evaluation criteria. Although the operation mode of agricultural supply chain finance development in Jilin Province is in the exploratory stage, its development experience has relatively distinctive representative characteristics. The type of development has guiding significance for the development of China's agricultural supply chain finance. The specific layout of this article is as follows. The first chapter is the introduction, which mainly expounds the basis of the research on the evaluation and development model of agricultural supply chain financial effect in Jilin Province, the research status at home and abroad, the main research contents, research methods, research innovation points and research technology routes. The second chapter is the literature review and theoretical basis. It mainly summarized related literatures such as agricultural supply chain finance, and expounds the basic theories such as information asymmetry theory, transaction cost theory and supply chain management. The third chapter is an overview of agricultural supply chain finance in Jilin Province. It mainly introduces the main types of agricultural supply chain finance in Jilin Province, the problems and main causes of agricultural supply chain finance in Jilin Province. The fourth chapter selects the main model of agricultural supply chain finance in Jilin Province, and builds a model to conduct empirical research on the main models of agricultural supply chain finance in Jilin Province. The fifth chapter evaluates the main models of agricultural supply chain finance in Jilin Province, selects data and indicators and uses the econometric model to evaluate and give empirical analysis results, and then promote the conclusion of this study. The sixth chapter is to promote the suggestions for the development of agricultural supply chain finance in Jilin Province, and propose a reasonable development model to ensure the healthy and rapid development of agricultural supply chain finance in Jilin Province. This thesis draws the following four conclusions. First, the current development stage of agricultural supply chain finance in Jilin Province is relatively junior. Although it has produced different development models of agricultural supply chain finance, the three development models have not yet produced great effects in the ideal, and should be rationally recognized in Jilin Province. The development status of agricultural supply chain finance, starting from reality, breaks through the financial bottleneck of agricultural development in Jilin Province. Second, cultivate more agricultural core enterprises, give play to the role of agricultural core enterprises in the agricultural industry, and encourage the reasonable bridging between financial institutions and agricultural core enterprises. Third, we should fully recognize the great role of financial instruments in the development of “agriculture, rural areas and farmers”, emancipate our minds, and call on agriculture to treat financial instruments correctly and rationally from the owners. Fourthly, the following countermeasures are proposed for the problems of agricultural supply chain finance in Jilin Province: improving the capacity of agricultural supply chain financial services; enhancing the role of core enterprises in the agricultural supply chain; actively participating in the construction of agricultural supply chain financial facilities; Ecological construction of agricultural supply chain financial services.

속단의 항당뇨 활성 및 활성 성분 품질평가

왕자영 중앙대학교 대학원 2024 국내박사

Dipsacaceae 과의 일종인 Dipsacus Asperoides C. Y. Cheng et T. M. A. (천속단)은 "Dipsaci Radix"로 알려진 뿌리 때문에 전통적으로 중국에서 약용 식물로 사용되었다. Dipsaci Radix는 AGE 형성에 대한 하향 조절 효과와 함께 항혈당, 저지질혈증 및 항산화 특성을 나타낸다고 제안된다. 그러나 현재 당뇨병에 대한 Dipsaci Radix에서 파생된 효과적인 성분에 대한 신뢰할 수 있는 보고는 없다. 이 연구에서는 DPPH, ABTS, FRAP, BSA-glucose, BSA-MGO, α- 글루코시다아제 체외 방법으로 Dipsaci Radix의 메탄올 추출물과 에틸 아세테이트 분획을 항당뇨제 및 항산화제의 잠재적인 천연 공급원으로 조사하였다. 추출물과 분획물에 페놀 성분이 존재하면 항산화 및 항당뇨 특성이 향상된다. 이는 분리된 모든 페놀 성분이 그러한 특성을 나타내었고, 그 중 절반(화합물 2, 4, 5, 8, 10)이 다방향 억제 효과를 나타냄에 의해 입증된다. 회색 관계 분석 (GRA)과 결합된 HPLC-UV 기술을 사용하여 활성 성분의 품질을 평가하고 활성 성분과 활성 사이의 스펙트럼 효과 관계를 더욱 명확히 하였다. 그중에서 '5-O-caffeoylquinic acid'이라는 활성 성분의 존재는 Dipsaci Radix의 항당뇨 및 항산화 특성에 크게 기여하였다. 이것은 전통적인 건강 제품 및 화장품 분야에서 광범위한 응용 전망과 의의를 가지고 있다. The plant Dipsacus asperoides C. Y. Cheng et T. M. A. (川续断), a member of the Dipsacaceae family, has been traditionally utilized as a medicinal plant in China due to its roots known as “Dipsaci Radix”. It is suggested that Dipsaci Radix exhibits antihyperglycemic, hypolipidemic, and antioxidant properties, along with down-regulating effects on AGEs formation. However, there are currently no reliable reports on the effective components derived from Dipsaci Radix for anti-diabetes. In this study, the methanol extract and its corresponding EA fraction of Dipsaci Radix were investigated as potential natural sources of antidiabetic agents and antioxidants by DPPH, ABTS, FRAP, BSA-glucose, BSA-MGO, α-glucosidase in vivo methods. The existence of phenolic components in extract and fraction enhances their antioxidant and antidiabetic properties. This is evidenced by the fact that all isolated phenolic compounds exhibited such properties, with half of them (Compound 2, 4, 5, 8, 10) displaying multidirectional inhibitory effects. Quality evaluation of active components using HPLC-UV technology combined with grey relational analysis provides further information regarding the spectrum-effect relationship between active components and their activities. Among them, the presence of the active ingredient ‘5-O-caffeoylquinic acid’ significantly contributes to the antidiabetic and antioxidant properties of Dipsaci Radix. This holds promising applications in traditional health products and cosmeceuticals.

Optimization of Nd:YAG laser - GMA hybrid welding process parameters onto 6061-T6 Al alloy

김항래 Graduate School, Yonsei University 2007 국내석사

A methodology for determining the optimum process parameters associated with Nd:YAG laser-GMA hybrid welding on 6061-T6 Al alloy is presented. In this study, the characteristic of weldability is determined on various process parameters which include welding wire type, shielding gas, laser power, laser focus, traveling speed, welding wire feed rate, root opening tolerance, and voltage.Experiments are performed with designated welding process parameters through L18 orthogonal array following Taguchi suggestion. For the evaluation of weldability, comparing the result of the ultimate tensile strength on the weld zone is the most essential criteria.In order to determine the optimum welding parameters, a grey relational analysis is carried out through the result of the ultimate tensile strength for each welding experiment. Based on the results of the grey relational analysis, a set of optimum welding parameters are obtained. Through the Taguchi DOE, the grey relational analysis is verified. Using the analysis of variance, predominant welding parameters are found.The results clearly show that the set of the optimum welding parameters determined by the grey relational analysis is much more improved compared to those from the preliminary set of experimental parameters.

Investigation of Single Point Incremental Sheet Forming Process: Extraction of Constitutive Models and Parameters Optimization

Mohanraj Murugesan 제주대학교 대학원 2021 국내박사

The incremental forming process (ISF) is one of the prominent sheet metal manufacturing techniques among the traditional forming methods; it’s becoming more noticeable these days due to its flexibility for manufacturing complex parts without utilizing predefined forming dies. Besides, the ISF process has higher formability of formed parts at a low cost than the conventional sheet forming methods. Additionally, the consistent and reasonable work material characterization in both room and warm temperature conditions under various strain rates is remarkably essential for modeling the numerical simulation and optimizing the sheet metal forming process working parameters. This research work’s contributions to the ISF process can be organized into the following sections: at first, the field emission scanning electron microscopy (FESEM) analysis combined with the energy-dispersive X-ray spectroscopy (EDS) technique is employed to conduct the elemental identification investigation. Secondly, the Digital Image Correlation (DIC) technique is used to investigate the work materials for assessing their material properties. For this purpose, the digital images at each deformation step, which provide complete displacement and strain data information until the fracture more accurately, are used. Further, the empirical models such as the original and modified Johnson-Cook models, modified Zerilli-Armstrong model, the strain-compensated Arrhenius-type constitutive equation, and hybrid machine learning model are proposed for describing the material flow behavior during hot deformation conditions. Overall, the proposed constitutive equation from the artificial neural network model combined with an optimization approach is proved to have good predictability in flow stress estimation. Eventually, the single incremental forming process (SPIF) is modeled using a customized vertical milling machine to investigate the SPIF process. The design of experiments (DOE) combined with the grey relational analysis (GRA), the response surface methodology (RSM), and statistical analysis of variance (ANOVA) is adopted for determining the process parameter's influence on the material formability without producing a rupture. The DOE procedure, a face-centered central composite design, is adopted for the AA3003-H18 Al alloy sheets for conducting the tests. The RSM procedure is used for optimizing the process parameters and identify the optimal experimental conditions. The statistically proposed model is observed from the outcome to be in good agreement with the experimental measurements. ANOVA is conducted to explain the proposed model's adequacy and the input factor's influence on the output factor. The statistically proposed regression model is observed to agree with the experimental estimations, having a higher R2 (0.8931) with lower prediction error (2.78%). The process parameters, such as step size, feed rate, the interaction effect of tool radius and step size, positively influence the response variable. Similarly, the input factors are optimized using the Taguchi method to minimize the surface roughness of formed parts. Firstly, according to the smaller-the-better, the S/N ratios are estimated to make a response table for getting the optimum level of process parameters. Minimum surface roughness is accomplished when the vertical step-size is smaller, the feed-rate is high, and the forming tool radius is high. The optimum level setting is acquired at 3.0 mm of forming tool radius (level 3), 3000 rpm of spindle speed (level 1), 0.10 mm of vertical step size (level 1), and 2000 mm/min of feed rate (level 4). The ANOVA results such as p-test and F--test revealed that vertical step-size, feed-rate, and tool radius significantly affect surface roughness. In contrast, the spindle speed is witnessed to have no significant influence on surface roughness. The Taguchi design results conferred better agreement with the actual measurements with moderate model error (approximately 1.8%). Additionally, the microstructural evaluation revealed that the thinning behavior tended to increase as forming depth reached its maximum; the material deformation was also observed to be uniform and homogeneous. ISF(점진 성형 공정)는 기존의 성형 방법 중 대표적인 판금 제조 기법 중 하나다. 사전 정의된 성형 다이를 활용하지 않고 복잡한 부품을 제조할 수 있는 유연성으로 인해 오늘날 더욱 주목을 받고 있다. 게다가, ISF 공정은 기존의 시트 성형 방법보다 저렴한 비용으로 성형 부품의 성형성이 우수하다. 또한 다양한 변형률 하에서 실내 및 온열 온도 조건 모두에서 일관되고 합리적인 작업 재료 특성은 수치 시뮬레이션을 모델링하고 판금 성형 공정 작업 매개 변수를 최적화하는 데 매우 중요하다. 본 연구의 ISF 공정에 대한 기여는 처음에는 field emission scanning electron microscopy (FESEM) 분석과 에너지 분산 X선 스펙트럼 분석(EDS) 기법을 결합하여 소자 식별 조사를 실시하는 섹션으로 나눌 수 있다. 둘째, DIC (Digital Image Correlation) 기법을 사용하여 재료 특성을 평가하기 위한 작업 재료를 조사한다. 이를 위해 파단까지의 변위 및 변형 데이터 정보를 제공하는 각 변형 단계의 디지털 영상이 사용된다. 또한, 고온 변형 조건에서의 재료 흐름 거동을 설명하기 위해 최초 및 수정된 Johnson-Cook 모델, 수정된 Zerilli-Armstrong 모델, 변형률 보정 Arrhenius형 구성 방정식, 하이브리드 기계 학습 모델 등의 경험적 모델을 제안한다. 전반적으로, 인공신경망 모델의 제안 구성 방정식은 최적화 접근법과 결합된 흐름 응력 추정에 좋은 예측 가능성을 가지고 있는 것으로 입증되었다. 결국, 단일 점진 성형 공정(SPIF)은 SPIF 공정을 조사하기 위해 맞춤형 수직 밀링 머신을 사용하여 고안되었다. Grey relational analysis (GRA), response surface methodology (RSM), statistical analysis of variance (ANOVA)과 결합된 실험 설계(DOE)는 공정 매개변수가 파열을 일으키지 않는 상황에서 재료 성형성에 미치는 영향을 위해 채택되었다. 실험 실행을 위한 AA3003-H18 Al 합금 시트에 표면 중심의 중앙 합성 설계인 DOE 절차가 채택되었다. RSM 절차는 공정 변수를 최적화하고 최적의 실험 조건을 식별하는 데 사용된다. 통계적으로 제안된 모델은 실험 측정과 잘 일치하는 결과로부터 관찰된다. ANOVA 분석은 제안된 모형의 적합성과 입력 인자가 출력 인자에 미치는 영향을 설명하기 위해 수행된다. 통계적으로 제안된 회귀 모형은 더 높은 결정 계수(R2)(0.8931)와 더 낮은 예측 오차(2.78%)를 갖는 실험 추정과 일치하는 것으로 관찰된다. 스텝 크기, 이송 속도, 공구 반지름의 상호작용 효과, 스텝 크기와 같은 프로세스 파라미터는 반응 변수에 긍정적인 영향을 미친다. 마찬가지로 입력 계수는 Taguchi 방법을 사용하여 최적화되어 성형 부품의 표면 거칠기를 최소화한다. 첫째, 작을수록, S/N 비율은 프로세스 매개변수의 최적 수준을 얻기 위한 반응 표를 만드는 것으로 추정된다. 최소 표면 거칠기는 수직 스텝 크기가 작고 이송 속도가 높으며 성형 공구 반경이 높을 때 이루어진다. 최적의 레벨 설정은 성형 공구 반경 3.0mm (레벨 3), 스핀들 속도 3000rpm (레벨 1), 수직 스텝 크기 0.10mm (레벨 1), 이송 속도 2000mm/min (레벨 4)에서 획득한다. P-시험 및 F-시험 등의 분산 분석 결과에 따르면 수직 단계 크기, 공급 속도 및 공구 반경은 표면 거칠기에 상당한 영향을 미친다. 반면, 스핀들 속도는 표면 거칠기에 큰 영향을 미치지 않는 것으로 확인되었다. Taguchi 설계 결과는 중간 정도의 모형 오차(1.8%)를 갖는 실제 측정값과 더 잘 일치하는 결과를 얻었다. 또한 미세구조 평가 결과 형성 깊이가 최대에 도달하면 박리 거동이 증가하는 경향이 있었으며 재료 변형도 균일하고 균일한 것으로 관찰되었다.