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Dong-Hwa YOON,Kwon-Min YANG,Hyeon-Gon OH,Mincheol KIM,Mona CHANG 국제융합경영학회 2021 융합경영연구 Vol.9 No.5
Purpose: This study is to analyze the changes of consumption patterns to diagnose the economic impacts on consumers’ market during COVID-19, and to suggest implications to overcome the new social and economic crisis of Jeju Island. Research design, data, and methodology: We collected a set of credit card transaction records issued by BC Card Company from merchants in Jeju Special Self-Governing Province for past 4 years from 2017 to 2020 from the Jeju Data Hub run by Jeju Special Self-Governing Province. The big data contains details of approved credit card transactions including the approval numbers, amount, locations and types of merchants, time and age of users, etc. The researchers summed up amount in monthly basis, transforming big data to small data to analyze the changes of consumption before and after COVID-19. Results: Sales fell sharply in transportation industries including airlines, and overall consumption by age group decreased while the decrease in consumption among the seniors was relatively small. The sales of Yeon-dong and Yongdam-dong in Jeju City also fell significantly compared to other regions. As a result of the paired t-test of all 73 samples in Jeju City, the p-value of the mean consumption of the credit card in 2019 and 2020 is significant, statistically proven that the total consumption amount in the two years is different. Conclusions: We found there are sensitive spots that can be strategically approached based on the changes in consumption patterns by industry, region, and age although most of companies and small businesses have been hit by COVID-19. It is necessary for local companies and for the government to be focusing their support on upgrading services, in order to prevent declining sales and job instability for their employees, creating strategies to retain jobs and prevent customer churn in the face of the crisis. As Jeju Province is highly dependent on the tertiary industry, including tourism, it is suggested to create various strategies to overcome the crisis of the pandemic by constantly monitoring the sales trends of local companies.
Cho, Yujang,Lee, Kyeongsoo,Park, Sangki,Ahn, Seongcheol,Kim, Wook,Kim, Junseo,Park, Siyoung,Sun, Jingzhe,Jung, Chanhee,Chung, Jikang,Chang, Mincheol,Choi, Dukhyun,Park, Jong-Jin Elsevier 2019 Nano energy Vol.61 No.-
<P><B>Abstract</B></P> <P>In the present study, a feather rotating-TENG (FTR-TENG) was developed by analyzing the properties of nanostructure and changes in friction areas by the aerodynamic motion of naturally evolved feathers. The motion and area of surface of the feathers vary according to the interlocking effect of the aerodynamic nanostructure that was found appropriate for the FTR-TENG in the present study. Owl feather, employed in the present study, demonstrated peak output performance of FTR-TENG of 51.4 V, 4.47 μA at 1.6 cm<SUP>2</SUP> of friction area and 7 m/s of wind speed. In addition, the positive surface charge potential of all feathers has increased by the electrostatic adsorption of hematoxylin, the natural dye, used to maximize the electricity generation efficiency of FTR-TENG by raising the positive triboelectric series of the β-keratin structure of feather. As a consequence, the performance of triboelectric generation was increased, despite the small area and low wind power, compared to the previous results of the rotational wind power generator. The owl feather demonstrated generation of 64.3 V and 6.55 μA with 1.6 cm<SUP>2</SUP> of frictional area at wind speed of 7 m/s, which represented an approximately 25% increase in voltage, and 47% increase in current, compared with that before adsorption.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This is a study of a new approach to increase the performance of the TENG using the hyper branched nanostructure feathers. </LI> <LI> The FTR-TENG was developed by analyzing the change of friction area by the aerodynamic motion of feathers. </LI> <LI> The adsorption of hematoxylin dye enabled a bigger positive triboelectric series, to maximize the electricity generation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A FTR-TENG based on the hyper-branched nanostructure of the feathers and the adsorption effect of hematoxylin is demonstrated for maximizing the efficiency of the wind-based TENG as an energy harvester. This is a study of a new approach to increase the performance of the TENG by adsorbing hematoxylin, a natural dye, on feathers, as well as the effect of varying friction area on the efficiency of the TENG using the feathers of the hyper branched nanostructure.</P> <P>[DISPLAY OMISSION]</P>
표면저항형 ITO 필름 센서의 표면처리 공정에 관한 연구
김동준(Dongjun Kim),안상수(Sangsu An),이창한(Changhan Lee),조영지(Youngji Cho),한민철(Mincheol Han),배찬영(Chanyoung Bae),전준수(Junsu Jeon),송유진(Yujin Song),장지호(Jiho Chang),하윤수(Yun-Su Ha),박재진(Jae-Jin Park),이문진(Moonjin Lee 한국물리학회 2024 새물리 Vol.74 No.1
A sensor that can measure the concentration of harmful chemicals in water using changes in surface resistance was fabricated using a metal oxide nanoparticle film, and the changes in sensor performance due to surface treatment processes were investigated. The influence of the surface residue of the organic binder used for film printing was focused on, and the changes in the properties of the film and sensor were observed. To remove the residual binder, a cleaning process was additionally introduced to the existing sintering process, and the changes in the properties of the ITO:CB film were observed according to the cleaning time, and the surface treatment time was optimized. It was confirmed that the sensor response improved as the cleaning time increased, and the optimal surface treatment conditions were determined to ensure good sensor operation.
Mincheol Chang(장민철) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
Conjugated polymer (CP)-based organic field effect transistors (OFETs) have been considered as potential candidates for gas sensing applications because of their unique advantages, such as light weight, multiparameter accessibility, ease of large-scale fabrication, and superior sensing capability enabled by gate-tunable current modulation. Recent studies have demonstrated the successful application of CP-based OFETs in gas sensors and have highlighted the urgency for improving the charge mobility and morphological features of the CP films for enhancing the performance of these sensors toward their practical applicability. This talk will demonstrate novel processing strategies for tuning the morphologies and charge transport properties of CP thin films, resulting in significant improvement in gas sensing performance of the CP film-based OFET gas sensors.
Overtourism in Jeju Island: The Influencing Factors and Mediating Role of Quality of Life
KIM, Mincheol,CHOI, Kwang-Woong,CHANG, Mona,LEE, Chang-Hun Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.5
The purpose of this study is to analyze how the problems caused by overtourism affect the quality of life of Jeju residents and their perceptions of the overtourism phenomenon by exploring related factors for future policy implications. In the research model, each independent factor related to tourists affects the quality of life of residents, and the mediation variable (QoL) ultimately agrees with overtourism. This study uses Partial Least Squares-Structural Equation Modeling (PLS-SEM), which is less influenced by the sample size. The research is based on 360 questionnaires. The test results showed that cultural factors affected the QoL statistically at 1% significance level, and economic factors were significant at 5%. The quality of life variable affects the agreement of overtourism (p-value 1% significance level). An indirect effect analysis on whether each independent factor affects the overtourism factor through the parameter of the QoL of the residents showed that the cultural factor at 5% level statistically affected it, and economic factors were significant at 10%. In conclusion, we recommend implementing both economic and cultural factors to reduce the negative perception of overtourism for the policy planning. Further research in multiple aspects should be continued to overcome the vulnerability of the Island destination tourism.
장민철(Mincheol Chang),문석하(Seokha Moon),김진규(Jinkyu Kim) ICT플랫폼학회 2023 ICT플랫폼학회 하계학술발표대회논문집 Vol.10 No.2
멀티뷰 카메라 영상을 사용한 자율주행 객체 탐지 알고리즘은 2차원의 정보를 3차원 조감도 (Bird’s-Eye-View) 좌표계로 바꾸어 물체인식을 진행한다. 그러나, 카메라 기반 객체 탐지 모델은 2차원 영상의 깊이 정보를 추정하기 어려움이 있고 부정확한 조감도 정보가 생성되므로 심각한 물체 오탐지가 발생한다. 본 연구에서는 기존 멀티뷰 카메라 기반 객체인식 모델의 거리추정 정확성과 조감도 상의 특징정보를 향상시키고자 지도 정보를 2D에서 3D 전환 과정에 융합해 3D 객체 인지 성능을 향상시키는 AI 모델을 개발하였다. 본 연구는 2023년도 대한전자공학회 하계학술대회 및 IEEE/CVF Winter Conference on Applications of Computer Vision 2024에서 발표됨.
Hematology and Serum Chemistry Values of Growing Miniature Pigs
Joohyun Jung(정주현),Jinhwa Chang(장진화),Haksang Kim(김학상),Junghee Yoon(윤정희),Mincheol Choi(최민철) 한국생명과학회 2008 생명과학회지 Vol.18 No.8
본 실험의 목표는 미니돼지에서 성성숙 전까지의 성장단계에서 혈액성분을 조사하는 것이다. 12마리 돼지를 이용하여 정맥에서 채혈하였다. 전혈과 혈청을 사용하여 혈액 및 혈액 화학치를 분석하였다. 그리고 성장단계별의 조사에서 각 성분은 평균과 표준편차로 나타내었다. 혈액분석에서 적혈구와 적혈구용적 그리고 혈소판에서 유의치 있는 변화가 있었다. 특히 적혈구와 적혈구용적은 4주령 군에서 가장 낮은 수치를, 반면에 혈소판은 4주령에서 가장 높은 수치를 보였다. 혈액 화학치에서는 glucose, GGT에서 유의치 있는 변화가 있었으며, 나머지 성분에서는 유의치 있는 변화가 없었다. 이러한 기본적인 혈액 및 혈액 화학치는 미니돼지의 정상 혈액학 연구와 그리고 성장단계별 이른 시기에 정상돼지를 판별하는데 유용하리라 생각된다. The purpose of this study was to establish blood reference values for miniature pigs from various growth ages before pre-puberty. 12 miniature pigs from two swine farms were sampled by jugular venipuncture. Routine hematological and biochemical determinations were performed using whole blood and serum. For the variables examined in each age group the means and the standard deviations were calculated. In hematological values, there are significant changes (p<0.05) in RBC, hematocrit and platelet values in each group. In RBC and hematocrit values, 4-week group shows the lowest level, whereas in platelet values, 4-week group shows the highest level. In biochemical values, there are significant chnges (p<0.05) in glucose and GGT in each group, and in other biochemical values there are no significant changes during growing periods. The values presented here may be useful for knowing the normal values for miniature pigs and also screening the normal pigs in the early days of their life and during the developemental stages.