후륜 구동 A/T 차량의 구동축 강성이 발진 가속에 미치는 영향

안동환(Donghwan Ahn),위효성(Hyoseong Wi),박진일(Jinil Park),이종화(Jonghwa Lee) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

Drivers are requiring higher drivability as the quality of life rises and the performance of the vehicle improves. Especially, drive shaft stiffness is closely related to drivability influential factors of a vehicle such as responsiveness, acceleration, and quietness. In order to make good drivability, powertrain of vehicle must generate driving force that corresponds to acceleration performance requested by the driver. In this paper, vehicle acceleration characteristics - one of the most important factor of drivability - are analyzed according to the drive shaft stiffness. In order to predict vehicle acceleration characteristics, a model to analyze the torque flow of an actual vehicle and a model coefficient measurement methodology are required, contribution of each component in the power distribution process must be understood, and a corresponding simulation model must be established. And based on the simulation result of this research, initial vehicle acceleration characteristics depending on driveshaft stiffness was predicted.

Co / NiMn의 교환 자기결합에 관한 연구

안동환(DongHwan Ahn),조권구(Kwon-Koo Cho),주승기(Seung-Ki Joo) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.4

Exchange coupling of Co/NiMn bilayers fabricated by RF magnetron sputtering method was studied. We investigated the variation of exchange coupling field (Hex) for different annealing temperature and time. The maximum exchange coupling field was obtained after 13hr annealing at 300℃. With respect to deposition sequence, it was demonstrated that NiMn-top bilayers had higher exchange coupling field than NiMn-bottom bilayers. Ta capping layer was shown to be essential in achieving exchange coupling and Auger Electron Spectroscopy (AES) proved that uncapped NiMn/Co bilayers did not have exchange coupling because of oxygen incorporation into film. We also observed the effect of Ta underlayer on exchange coupling. It was found that Ta underlayer had better not be used for attaining higher exchange coupling. XRD analysis showed that Ta underlayer helped bilayers develop texture, but it was not essential to exchange coupling of Co/NiMn bilayers, which is in contrast to NiFe/NiMn system. Furthermore, the NiMn and Co thickness dependence of exchange coupling has been investigated. The exchange coupling strength reached the maximum above 200 Å NiMn thickness and had inversely proportional relation with Co thickness.

차량 실내 소음 주파수 특성 변경이 운전성 평가에 미치는 영향

안동환(Donghwan Ahn),이동현(Donghyun Lee),김영관(Younggwan Kim),위효성(Hyoseong Wi),이진우(Jinwoo Lee),박진일(Jinil Park),이종화(Jonghwa Lee),김범수(Beomsoo Kim),이석재(Seogjae Lee) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

Vehicle performance is improving day by day. So drivers want to higher quality of drivability, which include acceleration performance, interior noise, vibrations and etc. In particular, the vehicle interior noise which is a major factor in the evaluation drivability is important factor. In this study, According to the frequency of vehicle interior noise, vehicle interior noise were analyzed which based on sound pressure level. On the basis of this analysis, the interior noise was changed through sound equipment, such as a microphone and equalizer. This interior noise was evaluated by drivers and identified a correlation between subject’s responses and changing of the frequency. As a result of this research, frequency bands and sound pressure levels which affect evaluation drivability were presented to meet the needs of consumers about acceleration, noise and vibration.

농촌 과소화마을의 변화 분석

박진우,이태호,안동환,Park, Jen-Woo,Lee, Taeho,An, Donghwan 한국농촌계획학회 2018 농촌계획 Vol.24 No.2

The main purpose of this study is to explore the factors that affect the transformation of over-depopulated rural villages. Specifically, we investigated the reasons of the rapid decrease in the number of over-populated rural villages shown by recent census data in spite of the continuing decrease of population in rural area. We used a binary-logit model and the Census of Agriculture, Forestry and Fisheries data(2010, 2015). The main results are summarized as followed: First, the over-depopulated rural villages with strong agronomic base are more likely to exit from over-depopulation. Second, returners from urban to rural have a positive impacts on the revival of over-depopulated rural areas. Thirds, improving the basic services accessibility of rural residents is also critical for keeping rural community more sustainable. These findings can be used to make effective strategies to revive the depopulated rural villages.

무단변속기에 의한 FTP-75 모드 연비 기여도 및 개선효과 분석

김현우(Hyeonwoo Kim),안동환(Donghwan Ahn),고현상(Hyeonsang Ko),박진일(Jinil Park),이종화(Jonghwa Lee) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

A study of AT(auto-transmission) is continuing to improve the fuel economy and powertrain performance with multistage technology in a lot of car companies. But an AT has a problem with stage limit. So a research of CVT(continuously variable transmission) which can drive on the ideal driving condition is going on until nowadays. Further more among these researches, an fuel economy improvement effect analysis is needed when an AT is replaced a CVT, Although a lot of time and money is required in this study simulation can reduce them. In this paper, we analyzed the fuel economy improvement effect when CVT installed on a gasoline vehicle instead of an AT. For this study, we took a FTP-75 mode on chassis dynamometer and analyzed the energy flow down in the CVT vehicle. And we composed modeling and did the simulation by AVL CRUISE based on the results of CVT vehicle analysis data. As a results, it could be accomplished 7.5% improvement of fuel economy when CVT replaced an AT.

농가의 리스크 밸런싱 행위 분석

추성민(Sungmin Cheu),안동환(Donghwan An) 한국농업경제학회 2018 農業經濟硏究 Vol.59 No.3

This study examines farm households’ risk balancing behavior in Korea. We use a SUR (seemingly unrelated regression) model to reflect the interdependence in farm households’ risk balancing behavior where they adjust their financial structure, off-farm work decisions, and consumption level, etc. We find that Korean farm households make strategic farm financial risk decisions, off-farm business decisions, and consumption adjustment in response to exogenous changes in expected farm risk or business risk. This study also shows that large farms make more use of off-farm risk balancing, while small farms appear to make more use of financial risk balancing and adjusting consumption level.

The effects of agricultural extension service on crop production, revenue, and profit: evidence from Mbale district in Uganda

이예영(Yeyoung Lee),안동환(Donghwan An),김태윤(Taeyoon Kim) 한국농업경제학회 2020 農業經濟硏究 Vol.61 No.3

Extension service plays a crucial role in agricultural production and household food security in Africa south of the Sahara (SSA). Despite the growing evidence on the effects of extension service on various outcomes, including crop productivity, technology adoption, and income, the evidence is limited on the impact on farmers’ ability to select and allocate inputs. While the effects of the extension service can vary with spatial variation, our study examines the effects of extension crop (maize, bean, and rice) production, revenue, and profit in Mbale district, located in the Eastern region of Uganda. We decompose the effects of extension into three: worker effect, input-allocation effect, and input-selection effect. Using household-level data based on the 204 farmers surveys, we examine the effects of extension service. Both worker and allocative effects of rice are found, while the former is more dominant than the latter. The results also show that the input-selection effect is more influential than the input-allocation effect. Overall, the findings suggest that much attention should be paid to rice farmers in Mbale district by supporting access to agricultural and market information with innovations in farm technology that enable farmers to receive optimal returns in crop production. Given the effects of extension service, tailored strategies and agricultural programs are suggested to enhance the capacity of farmers and increase profitable marketed output that will help to promote sustainable development.

북한 대중예술 및 미디어 보도의 표현분석을 통한 협동 농장 정책 연구: 분조의 주인과 로동신문을 중심으로

임채환 ( Lim Chehwan ),안동환 ( An Donghwan ) 북한연구학회 2020 北韓硏究學會報 Vol.24 No.2

Since the 2000s, North Korea has implemented various economic reform measures to overcome its economic difficulties, and various agricultural policies have been introduced in the agricultural sector. However, North Korea is still the poorest country in the world, and its failure to increase food production has led to chronic shortages. This study uses North Korea’s popular arts (the owner of the movie division) and media coverage (Rodong Sinmun) to examine the agricultural policies and practical achievements promoted by the North Korean authorities in micro-unit (cooperative farm) and suggest the cause of the failure of the agricultural administration. While qualitative analysis methods, which are not based on statistics and numerical data, are the limitations of research, at the same time, it can be evaluated as a new effort that has been attempted to view changes and actual conditions in North Korea’s agricultural administration under circumstances where quantitative data in the North is restricted. According to the analysis, the terms used in the Rodong Sinmun to describe how cooperative farms operate in 2012 and in the period between 2015 and 2020 were very similar. The North Korean authorities were still emphasizing the urgency of increasing food production through various investigations, and the agricultural policy was also emphasizing the introduction and proper use of the Fumic fertilizer as a major agricultural input, by enhancing the knowledge of farm workers and making them more devoted to their work . The fact that the policy of operating cooperative farms has not changed significantly is believed to have served as one of the main reasons for the failure of North Korea’s agricultural reform.

원예부문의 수출 결정요인 분석

임정빈 ( Jeongbin Im ),안동환 ( Donghwan An ),성재훈 ( Jae-hoon Sung ) 한국농업정책학회 2011 농업경영정책연구 Vol.38 No.1

In this study, we investigated the factors influencing the exports of horticultural sector in Korea. In particular, we estimated the gravity-type export equations for three horticultural products. The findings of this study are as follows. First, the effects of distance on the export of horticultural products except fruit are significant. Second, complementation in trade has positively related with export of horticultural product, except fresh vegetable. Trade of fresh vegetable are more likely to be intra-industry trade rather than inter-industry trade due to the difference of cropping period. Third, foreign direct investment does have a significant positive effects on the export of fresh vegetable and flower. Fourth, tariff is positively related with export of fresh vegetables, and the entry into WTO has significant positive effects on the export of fresh fruit. The results implies that neighborhoods including China, Japan, and emerging Asian countries become more important exporting market of horticultural sector. And foreign direct investment and trade specialization is also important to increase the export of horticultural product.

순자산가치를 고려한 농가의 빈곤탈출 요인 분석

강민정(Minjeong Kang),안동환(Donghwan An) 한국농업경제학회 2017 農業經濟硏究 Vol.58 No.3

This study examined the factors affecting exit from poverty of farm household based on an income net worth approach by using a stratified Cox proportional hazard model called PWP-CP model. We found that exit from poverty is more difficult for the households who are young, female headed, and small scale. Our results also show that farm households with less land and transfer income including subsidies are more likely to suffer from long-term poverty. These results imply that with an expansion to subscribe Reverse Mortgage Products such as farmland pensions, income diversification policies such as the 6th-industrialization policies, and the expansion of a fundamental welfare policy should be also considered important in order to solve long-term poverty problems of the farm household.