회전각가속도가 가스 포일 스러스트 베어링의 마찰 및 마모 특성에 미치는 영향

황성호,김대연,김태호 한국트라이볼로지학회 2023 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.39 No.5

This paper represents an experimental investigation of the effect of angular acceleration on the friction and wear performances of a gas foil thrust bearing(GFTB). In this study use a typical GFTB with six pads for evaluating the friction and wear performances. The outer radius of the bearing is 31.5 mm, the total bearing area is 2,041 mm2, and the bump foil and incline(ramp) height are the same 500 μm. The newly developed GFTB test rig for measuring friction torque and coefficient measures axial load, drag torque, lift-off speed, and touch-down speed during the test. The experiment conducted for angular accelerations of 78.5, 314.2, and 328.3 rad/s2 at axial loads of 5, 10 and 15 N, respectively. The start-up friction coefficient increases with increasing axial load at the same angular acceleration. The friction coefficient decreases with increasing angular acceleration at the same axial load. As the angular acceleration increased, the lift-off speed at the motor start-up increased, and the touch-down speed at the motor stop decreased. The wear distance of GFTB for 1 on/off cycle increases with increasing axial load at the same angular acceleration, and decreases nonlinearly with increasing angular acceleration at the same axial load. These test results imply that adjusting the rotational angular acceleration helps reduce bearing friction and wear.

무선 센서 네트워크에서 IEEE 802.15.4 MAC의 이동성 지원

황성호,Hwang, Sung-Ho 한국정보통신학회 2007 한국정보통신학회논문지 Vol.11 No.11

전통적인 센서 네트워크는 고가의 센서와 케이블로 연결되어 있어, 센싱 데이터를 수집할 때 유연성이 떨어지는 단점을 가지고 있다. WSN은 저가의 장비를 사용하고, 임무를 여러 노드에서 나누어서 수행하기 때문에 다각도에서 세밀한 데이터를 수집할 수 있다. 본 논문에서는 대한석탄공사의 작업현장에서 IEEE802.15.4 MAC을 이용하여, 채탄 작업환경을 그대로 적용한 채탄토폴로지를 구성하였다. 채탄 작업시에 작업 관리자의 이동성 지원을 위한 모델들을 제안하였고, 시뮬레이션을 수행하여 최적의 모델을 선정하였다. 본 논문의 결과는 대한석탄공사와 다른 광업소에서 WSN을 적용할 때 중요 자료로 사용할 수 있을 것이다. The traditional sensor network is composed of the cable and the sensor of high price, when collecting a sensing data, there is a weak point which is not pliability. WSN uses the equipment of low price, it will be able to collect the data which is diverse from various node. In this paper we composed coal mining topology which used IEEE802.15.4 MAC in Korea Coal Corporation site. We proposed models for the mobility support of the work manager from the coal mining, we selected the optimum model through simulation experiments. When applying the WSN in the Korea Coal Corporation and other mines, this result can be used as a basis.

제 10 장 합창곡 "하두봉 신화"를 바탕으로 한 나의 작품세계

황성호 아시아음악학회 2001 아시아음악학 총서 Vol.3 No.-

미생물 실험실에서의 부유 곰팡이 농도의 계절별 변이와 환경영향

황성호,홍순열,석지원,윤충식 한국환경보건학회 2016 한국환경보건학회지 Vol.42 No.1

Objectives: This study aimed to assess temporal changes in the level of culturable airborne fungi (CAF) in threemicrobiology laboratories and determine the environmental factors associated with CAF level. Methods: CAF levels were determined once per month from March 2011 to February 2012 in threemicrobiology laboratories. An Andersen one-stage sampler was used for five minutes, three times per day tocollect the CAF. Arithmetic means of CAF concentrations and standard deviation (SD) were calculated. AMann-Whitney test was applied to compare the differences between environmental factors such as divided roomby structure of laboratory, use of humidifier, and use of air-conditioner. Correlation analysis was also applied toidentify the association between CAF concentrations and environmental factors. Results: CAF levels demonstrated an increasing tendency in summer, and the three laboratories showedconsistent seasonal patterns. Temperature and relative humidity (RH) were associated with CAF levels. Whenthe humidifier was off, CAF concentrations were significantly higher in study rooms than in study rooms inwhich the humidifier was on. Conclusion: CAF levels in indoor microbiology laboratories varied greatly depending upon the temperature andRH and whether a humidifier was used.

기계공학에서의 PBL적용 교과과정 개발: 제품해체 설계추론

황성호,권오채,김용세,Hwang Sung-Ho,Kwon Oh-Chae,Kim Yong-Se 한국공학교육학회 2005 공학교육연구 Vol.8 No.1

최근 들어 '학습자 중심의 자기주도 학습' 이라는 새로운 교육패러다임에 대한 관심이 집중되면서, 문제중심학습(Problem-Based Learning; PBL)이 학생의 과학적 사고능력 및 지식의 확장, 적용력, 비판적 지식창출 능력, 창의적 문제해결 능력을 향상시킬 수 있는 방법으로 주목받고 있다. 기계공학 분야에서도 이러한 PBL교육기법을 적용한 교과과정 개발에 대한 노력들이 활발히 전개되고 있으며, 본 논문에서 제시하는 '제품해체 설계추론'교과목도 그러한 교육방법을 적용한 한 예시라 할 수 있다. 제품해체 설계추론은 제품개발에 있어서 그 기여도가 가장 높은 기초물리학이 실제 제품에 어떻게 응용되고 있는가를 학생들이 직접 참여하여 체험할 수 있게 하는 제품해체 학습법 (product dissection)을 도입하여, 설계추론(design reasoning)에 있어서 기초물리학의 중요성을 인식시키는 한편, 다양한 기초과학에 대한 흥미를 유발할 수 있는 실습위주의 교과목이라 할 수 있다. 이러한 교과목을 통하여 창의적 설계 인력 양성에 큰 역할을 할 수 있을 것으로 기대한다. Recently, a new education paradigm 'Self-directed Learning' has attracted considerable attention. Problem-Based Learning (PBL) has been recognized as methodology to help students expand scientific thinking and knowledge. improve applicability, develope critical knowledge, and creatively solve problems. There have been significant efforts to develope PBL-based courses in mechanical engineering. A new PBL-based, multi-disciplinary course 'Product Dissection and Design Reasoning' has been developed in this paper. The course examines the way in which products and machines work and is intended to show freshman or sophomore level students how fundamental physical principles relate to engineering practice through hands-on dissection experience : thus, the course emphasizes the importance of knowledge of the fundamental physics for design reasoning. The primary role of this course is to develop creative design manpower. This paper describes the philosophy and content of this course and presents results from one year of development.

장애인 스포츠 선수들의 지도자 전문성과 선수만족 및 자기관리의 구조적 관계

황성호,김근국 한국스포츠학회 2020 한국스포츠학회지 Vol.18 No.2

이 연구의 목적은 장애인 스포츠 선수들의 지도자의 전문성과 선수만족, 자기관리의 구조적 관계를 분석하기 위한 것이다. 설문조사는 경기도 이천 장애인 훈련원에서 훈련하는 전국 대표 장애인 스포츠 선수와 국내 대회에 참가한 160명 을 대상으로 진행되었으며 최종적으로 152명의 표본으로 분석 되었다. 수집 된 표본은 SPSS18.0과 AMOS 18.0 프로그 램을 사용하여 빈도분석, 확인적 요인분석과 신뢰도 분석, 상관분석, 구조적 방정식 모델링을 통해서 분석했으며, 결과는 다음과 같다. 첫째, 요인들과의 관계를 식별하기 위한 가상 모델의 적합은 지도자 전문성과 선수만족, 선수만족과 자기관 리는 직접적 효과가 있었고, 부분적으로 적합성 기준으로 지도자전문성과 자기관리는 간접적 효과로 만족했다. 둘째, 매개 효과에 대해 설정된 가설을 검증하여 지도자 전문성과 자기관리의 관계에서 선수만족의 매개효과를 분석한 결과, 선수만족은 지도자 전문성과 자기관리의 관계에서 통계적으로 유의한 완전히 매개 된 것으로 확인되었다. 이 연구결과는 현장의 있는 선수와 지도자들에게 있어서 유용한 기초자료가 될 것을 기대하며, 추후 연구로는 다양한 대상으로 한 연구를 진행할 필요성이 있고, 이러한 연구를 토대로 보다 효과적인 검증이 이루어질 것이라 판단된다. The purpose of this study is to analyze the structural relationship between the leadership expertise of disabled sports players and athlete satisfaction and self-management. The survey was conducted on 160 disabled athletes training at the Icheon Disabled People's Training Center in Gyeonggi Province and finally analyzed as a sample of 152 athletes who participated in the domestic competition. The collected samples were analyzed through frequency analysis, positive factor analysis and reliability analysis, correlation analysis, and structural equation modeling using the SPSS18.0 and AMOS 18.0 programs. The results are as follows: First, the suitability of the virtual model to identify the relationships with the factors showed direct effects of leader expertise and athlete satisfaction, athlete satisfaction and self-management, and indirect effects of leader expertise and self-management on a partially conformity basis. Second, the hypothesis set for the mediating effect was verified and the analysis of the mediating effect of the athletes' satisfaction in the relationship between leadership expertise and self-management confirmed that the athletes' satisfaction was completely mediated. The findings are expected to be a useful basis for athletes and leaders in the field. Further research needs to be conducted on a variety of subjects, and it is believed that more effective verification will be made based on these studies.

Trend of ESG in Japan: Based on ESG Investment

황성호 한일경상학회 2022 韓日經商論集 Vol.95 No.-

Purpose: Japan is experiencing a rapid increase in ESG investment in addition to the SDGs in response to the tide ofthe times surged by global ESG. With global efforts to build a sustainable society, the recognition that non-financialinformation affects the sustainability of long-term companies is spreading. The Japanese government is making astruggle to achieve its target after declared to achieve “carbon neutrality” by 2050. After GPIF has led the way inESG investment from 2015, ESG investment increased up to 55% during the last five years. However, Japanese ESGranking by ESG rating agencies is still not high. Japan is expected to focus on ESG investment by financial institutionsfor the time being. While the correlation between ESG investment and performance is still unclear, the question ofpersistence of ESG investment is also being continued. The supporting SDGs through ESG Investment of consideringthe environment and society is important. This paper is to survey the trends and issues of ESG in Japan related toESG investments and insurance industry in Japan. Research design, data, and methodology: The paper focused on the trend of ESG in Japan through previousESG-related literature and the related articles retrieved from homepages of institutions for verifying recent data. Thispaper is composed by three areas, first, the trend of each ESG engagement of Japanese companies, second, thetrend of ESG investment and third, the ESG trend of Insurance industry in Japan. Results: ESG investment in Japan has been leading the long term strategies of Japanese companies to be moreactively involved in ESG. The correlation between ESG investment and financial performance is positive until nowaccording to previous studies. However, after the face of huge risks such as COVID-19, the evaluation of ESGinvestment should be considered as a risk mitigation effect. Japanese companies see ESG as an opportunity toimprove the value of existence and future business opportunities. It is also true for Japanese companies to see ESGas the critical issues for meaningful to stakeholders, higher ROE and positioning with SDGs. The empirical researcheson the criteria for ESG investment are suggested to need more time series data and risk mitigation effects. Thecorrelation of ESG-related indexes, the standardization ESG rating and the correlation of ESG and corporate valuecreation also should be further studied in the future. Implications: After the 2020 declaration of carbon neutrality, Japan is committed to achieving the goals of SDGsthrough ESG investment. However, it is true that it has yet to be evaluated lower by the ESG rating agenciescompared to the rapid increase in ESG investment. Long-term research on the correlation between ESG investmentand financial performance be emphasized specially under COVID-19 and low growth. ESG-related social environmentis expected not to end in a short-term boom in Japan. Korea and Japan have also similar financial and businessstructures, and this paper can be referred to study Korea’s future ESG policies.

초음파를 이용한 미생물과 현탁입자의 회수에 관한 연구

황성호,구윤모 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.6

미생물을 포함한 현탁입자의 회수나 여과, perfusion system에서의 세포의 포집 등에 초음파를 이용하는 것은 널리 알려져 있다. 이러한 초음파를 이용한 미생물과 고분자 입자의 회수에서 acoustic cell settler를 구성하고 있는 진동자와 반사막간의 거리, 초음파의 진동수, 초기 정치 시간, 현탁액의 농도 그리고 여과액(filtrate)의 회수속도가 분리효율에 미치는 영향에 대해 연구하였다. 미생물은 대장균과 빵효모를 사용하였으며 각각의 크기는 약 1.8㎛, 4.8㎛이었고, 고분자입자는 polyaniline을 사용하였으며 1-13㎛ 크기의 입자 분포를 가진 것이었다. 초음파의 진동수 1.3과 3MHz에서 진동자와 반사막간의 거리와 초기 정치시간을 변화시키며 회수 특성을 관찰하였다. 초음파의 진동수 1.3과 3MHz에서는 대장균, 빵효모와 ployaniline 모두가 88%이상의 높은 분리효율을 보였으나, 1.3MHz의 낮은 초음파 진동수에서는 크기가 큰 빵효모는 90%이상의 높은 분리효율을 보였으나, 입자크기가 작은 대장균과 1-2㎛ 크기의 polyaniline 입자는 초음파의 정상파 내에 포집이 되지 않고 유출되어 낮은 분리효율을 보였다. 회수 속도에 대해서는 입자의 크기가 큰 빵효모의 경우에 높은 회수 속도에도 settler내에서 세포가 유지되어 높은 분리효율을 보였으나, 대장균의 경우에는 settler내에서 유지가 어려웠다. Recovery of suspended particles using acoustic cell settler was investigated. The acoustic cell settler has advantages over conventional filtration devices which are subject to media contamination such as fouling, resulting in needs for regular regeneration and replacement. The acoustic cell settler consists of transducer, reflector and acoustic chamber. We studied for several important factors affecting the separation efficiency, such as distance between transducer and reflector, frequency of ultrasound, initial holding time, concentration of particles and harvest rate of filtrate. We did experiment for the recovery of Escherichia coli, Saccharomyces cerevisiae(bakers yeast) with size of 1.8 and 4.8㎛, respectively, and a polymeric particle, polyaniline. In the 1.3 and 3 MHz ultrasound, effect of change in distance between transducer and reflector and initial holding time were experimentally studied. We measured the maximum harvest rate of filtrate with the high separation efficiency. With the ultrasound at 3 MHz, separation efficiency were 95%, 96% and 88% for bakers yeast, polyaniline and E. coli, respectively. At ultrasonic frequency of 1.3 MHz, bakers yeast showed separation efficiency of higher than 90% whereas particles smallr than 2㎛, such as polyaniline and E. coli, were not well separated.

VHF/UHF 주파수 대역을 위한 AWBN(Adaptive Wireless Broadband Network) 시스템 개발

황성호,이정석,김기홍,민준기,박용운 한국방송공학회 2007 방송과 미디어 Vol.12 No.3

웃음요법이 건강한 삶에 미치는 효과: 메타분석

황성호,정현철,황지원 한국융합학회 2019 한국융합학회논문지 Vol.10 No.9

The purpose of this study is to identify the effects of laughter therapy on healthy life of human through meta-analysis of literature. Based on domestic and foreign academic databases, 495 foreign and 199 domestic literature were reviewed focusing on "quality of life," as the ultimate goal of health. The final seven literature were extracted. Analyses was performed in R version 3.5.1. Significant differences (SMD=0.23, p<0.01) were shown in the pre-post comparisons of experimental groups using the mean difference (effects size) analysis of the extracted samples. Significant results were not shown in meta regression analyses setting explanatory variables as ‘treatment sessions and durations’ and outcome variables as ‘treatment effects of laughter therapy’. This study is meaningful in comparative analyses of pre-post experimental groups to establish 'laughter therapy' has a significant effect on improving ‘quality of life' and is a useful intervention method, especially for older people, and older women with depression. 본 연구의 목적은 문헌의 메타분석을 통해 웃음요법이 인간의 건강한 삶에 미치는 효과를 규명하는데 있다. 국내·외 학술데이터베이스를 토대로 건강의 궁극적인 목적인 “삶의 질”을 중심으로 국외 495편, 국내 199편의 문헌을 검토하였다. 최종 7편의 문헌이 추출되어, 분석은 R version 3.5.1로 수행하였다. 추출된 표본의 평균차이(효과크기)분석을 활용하여 실험군의 사전·사후 비교에서 유의미한 차이(SMD=0.23, p<0.01)를 보였으나, ‘웃음요법의 처치회기와 기간’을 설명변수로, ‘웃음요법의 처치효과’를 결과변수로 설정한 메타회귀분석은 유의미한 결과를 보이지 않았다. 본 연구는 실험군의 사전·사후 비교분석에서 ‘웃음요법’이 ‘삶의 질 향상’에 유의미한 효과를 지니고 있고, 특히 노인, 우울증을 앓고 있는 중년 이상의 여성에게 유용한 중재기법임을 규명하였다는 데 그 의의가 있다.