우리나라 여성의 만혼(晩婚) 이 첫 출산간격에 미치는 영향

정우진,이경애,이선미,Chung, Woo-Jin,Lee, Kyoung-Ae,Lee, Sun-Mi 대한예방의학회 2006 예방의학회지 Vol.39 No.3

Objectives: The purpose of this study was to examine the effect of women's late age of marriage on the interval between marriage and their first birth Methods: Data from Year 2000 Korea National Fertility Survey was collected through direct interview questionings, and the data was analyzed based on randomly selected sampling. In particular, the married women (N=5,648) were analyzed for the factors that determined the first-birth interval by performing Cox's proportional hazard model survival analysis. Results: Unlike previous findings, the woman whose age of marriage was 30 or more was more likely to delay the birth of her first baby than were the other women who married earlier. Further, a woman's age at marriage, a woman's residence before marriage, her husband's religion, her husband's level of education and the difference in age between the woman and her husband significantly influenced the first-birth interval. In contrast, for a married woman, her age, level of education, current residence and religion were not significant predictors of her first birth interval. Conclusions: Our study showed that women who married at the age of 30 years or more tend to postpone their first birth in Korea. When facing the increasing number of women who marry at a late age, the Korean government should implement population and social policies to encourage married women have their first child as early as possible.

우리나라 남성 흡연자의 금연의향 담배가격 분석

정우진,이선미,신가영,임승지,조경숙,Chung, Woo-Jin,Lee, Sun-Mi,Shin, Ka-Young,Lim, Seung-Ji,Cho, Kyung-Sook 대한예방의학회 2008 예방의학회지 Vol.41 No.3

Objectives : The purpose of this study was to estimate the willingness to quit cigarette price among Korean male adults, and to examine the factors affecting the willingness to quit cigarette price. Methods : The data was collected by a random digit dial telephone survey. 702 samples were analyzed by using t-tests, ANOVA and OLS regression analysis. To estimate the willingness to quit cigarette price, smokers were asked dichotomous questions with open-ended follow-up and the starting point of the price was randomized by one of 5 bid prices elicited from a pilot study. Results : The mean of the willingness to quit cigarette price was 4,287 Won per package, which was about 2,000 Won higher than the mean of the actual price the smokers now paid. About 41% of respondents were willing to quit smoking if the price of cigarette would be increased by 3,000 Won, and if the price would be increased by 20,000 Won, all respondents were willing to quit smoking. The factors associated with the willingness to quit cigarette price were the place of residence, the amount of smoking and the degree of exposure to smoking through the mass media. Conclusions : The results showed that to get people to quit smoking, increasing the cigarette price would obviously be effective and much higher prices have a greater effect. Furthermore, to enlarge the effect of increased cigarette prices, providing more cessation programs to small towns, reducing the amount of smoking and decreasing or prohibiting advertisements of cigarettes and smoking in the mass media will be efficient.

음주의 사회경제적 비용 추계

정우진,전현준,이선미,Chung, Woo-Jin,Chun, Hyun-Jun,Lee, Sun-Mi 대한예방의학회 2006 예방의학회지 Vol.39 No.1

Objectives: We wanted to estimate the annual socioeconomic costs of alcohol drinking in Korea. Methods: The costs were classified as direct costs, indirect costs and the other costs. The direct costs consisted of direct medical costs, indirect medical costs and subsidiary medical costs. Particularly, the medical costs and population attributable fraction for disease were considered to reflect the calculation of the direct medical costs. The indirect costs were computed by the extent to which the loss of productivity and loss of the workforce might have occurred due to changes in mortality and morbidity according to alcohol drinking. The other costs consisted of property loss, administration costs and costs of alcoholic beverage. Results: The annual costs, which seemed to be attributable to alcohol drinking, were estimated to be 149,352 hundred million won (2.86% of GDP). In case of the latter, the amount includes 9,091 hundred million won for direct costs (6.09%), 62,845 hundred million won for the reduction and loss of productivity (42.08%), 44,691 hundred million won for loss of the workforce (29.92%), and the other costs (21.91%). Conclusions: Our study confirms that compared with the cases of Japan (1.9% of GNP) and the other advanced countries (1.00-1.42% of GDP), alcohol drinking incurs substantial socioeconomic costs to the Korean society. Therefore, this study provides strong support for government interventions to control alcohol drinking in Korea.

우리나라 성인 남성의 흡연여부와 흡연량에 미치는 담배가격의 효과

정우진,이선미,최승주,신가영,조경숙,임승지,Chung, Woo-Jin,Lee, Sun-Mi,Choi, Sung-Joo,Shin, Ka-Young,Cho, Kyung-Sook,Lim, Seung-Ji 대한예방의학회 2007 예방의학회지 Vol.40 No.5

Objectives: To determine the impact of cigarette prices on the decision to initiate and quit smoking by taking into account the interdependence of smoking and other behavioral risk factors. Methods: The study population consisted of 3,000 male Koreans aged ${\ge}20$. A survey by telephone interview was undertaken to collect information on cigarette price, smoking and other behavioral risk factors. A two-part model was used to examine separately the effect of price on the decision to be a smoker, and on the amount of cigarettes smoked. Results: The overall price elasticity of cigarettes was estimated at -0.66, with a price elasticity of -0.02 for smoking participation and -0.64 for the amount of cigarettes consumed by smokers. The inclusion of other behavioral risk factors reduced the estimated price elasticity for smoking participation substantially, but had no effect on the conditional price elasticity for the quantity of cigarettes smoked. Conclusions: From the public health and financial perspectives, an increase in cigarette price would significantly reduce smoking prevalence as well as cigarette consumption by smokers in Korea.

토착 미생물을 이용한 MTBE와 BTEX의 혐기성 생분해 연구

정우진,장순웅,Chung, Woo-Jin,Chang, Soon-Woong 한국지하수토양환경학회 2016 지하수토양환경 Vol.21 No.3

The simultaneous biodegradation between MTBE (Gasoline additives) and BTEX (Benzene, Toluene, Ethyl-benzene, o-Xylene, m-Xylene, p-Xylene) was achieved within a competitive inter-relationship, with not only electron accepters such as nitrate, sulfate, and iron(III) without oxygen, but also with electron donors such as MTBE and BTEX. Preexisting indigenous microorganisms from a domestic sample of gasoline contaminated soil was used for a lab-scale batch test. The result of the test showed that the biodegradation rate of MTBE decreased when there was co-existing MTBE and BTEX, compared to having just MTBE present. The growth of indigenous microorganisms was not affected in the case of the MTBE treatment, whereas the growth of the microorganisms was decreased in combined MTBE and BTEX sample. This may indicate that an inhibitor related to biodegradation when BTEX and MTBE are mixed will be found. This inhibitor may be found to retard the anaerobic conditions needed for efficient breakdown of these complex carbon chain molecules in-situ. Moreover, it is also possible that an unknown competitive reaction is being imposed on the interactions between MTBE and BTEX dependent on conditions, ratios of mixture, etc.

IEEE 802.16e에서의 에너지 절약을 위한 적응적 최소 수면 구간 결정 알고리즘

정우진 ( Woo Jin Jung ),이태진 ( Tae-jin Lee ),정윤원 ( Yun Won Chung ),정민영 ( Min Young Chung ) 한국인터넷정보학회 2008 인터넷정보학회논문지 Vol.9 No.4

IEEE 802.16e는 고속의 이동성을 지원하는 이동단말들의 전력소모를 최소화시키기 위하여 수면 모드(sleep mode)를 정의하고 있다. 수면 모드를 적용한 MSS(Mobile Subscriber Station)들은 수면 구간 사이에 존재하는 청취(Listening) 구간 동안 BS(Base Station)으로 부터 수신할 데이터 프레임이 존재하지 않는다는 메시지를 수신하면, 자신의 수면 구간 값을 이전 수면 구간 값의 두 배로 증가시킨다. 수면 구간 값이 최대 수면 구간 값에 도달하면, 수면 구간 값을 최대 수면 구간 값으로 고정함으로써 전력사용을 억제한다. 그러나 이러한 방식은 MSS가 최소 수면 구간 값에서 시작한 후 BS로부터 수신할 데이터 프레임이 존재하여 수면 모드를 종료할 때 까지 다수의 수면 구간과 청취 구간을 반복하게 되어 스위치 온, 오프에 의한 전력 소모 증가를 야기 시킨다. 본 논문에서는 MSS의 에너지를 효과적으로 사용하기 위하여 현재 수면 모드 종료 시 사용되었던 수면 구간 값을 다음 수면 모드의 최소 수면 구간 값으로 사용하는 최소 수면 구간 결정 알고리즘을 제안한다. 또한, 시뮬레이션을 통해 제안 방식과 기존 IEEE 802.16e 수면 모드 방식에 대하여 에너지 소모량 및 막힘확률에 대한 성능을 비교 평가한다. 제안하는 알고리즘은 기존 IEEE 802.16e 수면 모드 알고리즘과 비교하여 막힘확률은 동일한 성능을 보이나, 에너지 소모량은 약 30%의 절감효과를 보인다. IEEE 802.16e has adopted sleep mode to minimize energy consumption of mobile nodes with high speed mobility. If the Base Station (BS) has no data to be sent to a Mobile Subscriber Station (MSS) at the instant of ending sleep window of the MSS, the MSS increases its sleep window interval by double until the window interval reaches to the maximum sleep window interval. Thus, during the operation of sleep mode, MSS repeatedly performs switch on/off action until there exist frames to be received from BS. The switch on/off operation significantly consumes energy of MSS. To effectively deal with the energy of the MSS, this paper proposes an algorithm which decides the minimum sleep window interval that will be used in next sleep mode based on the current sleep window interval. We evaluate the performance of IEEE 802.16e sleep mode algorithm and our proposed algorithm in terms of energy consumption and blocking probability. Compared with the current sleep mode algorithm used in IEEE 802.16e, the proposed algorithm decreases the energy consumption by about 30% without increasing blocking probability.

Improvement on Life of Planet Gear in Reduction Gearbox for Electric Forklift

Woo-Jin Chung(정우진),Da-Vin Ahn(안다빈),Ji-Tae Kim(김지태),Young-Jun Park(박영준) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11

하우징 기하공차를 고려한 감속 기어박스의 베어링 반력 해석

정우진 ( Woo-jin Chung ),조승제 ( Seung-je Cho ),박영준 ( Young-jun Park ),김기수 ( Ki-soo Kim ),이강희 ( Kang-hee Lee ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.2

베어링은 기계시스템에서 회전하고 있는 축의 위치를 고정시키고, 축 자체의 자중과 축에 작용하는 하중을 지지하면서 축을 회전시킨다. 즉, 베어링은 기계요소의 마찰을 감소시키고 하중을 지지하기 때문에 기계시스템에서 필수적인 부품이다. 베어링 설계 시에는 축의 회전 속도, 베어링 반력, 접촉각, 내부 틈새 등이 고려된다. 본 연구의 목적은 감속 기어박스의 하우징 기하공차를 고려하여 베어링 반력을 해석하는 것이다. 분석대상인 기어박스는 3개의 평행축 기어 세트로 이루어져 있으며, 기어박스 내의 보조 장치들을 구동하기 위한 감속 기어박스로 사용된다. 실제 제작과 동일한 조건으로 베어링 외륜과 하우징의 억지끼움 정도를 반영하였고 하우징 기하공차를 고려하기 위해 하우징에 대한 베어링 자리 가공에 따른 동심도 오차를 반영하였다. 기어박스는 상용소프트웨어인 RomaxDESIGNER를 이용하여 모델링하였다. 베어링 반력이 최대로 나오는 조건을 확인하기 위해 실험 계획법을 사용하여 13개의 해석 모델을 만들었다. 실험 인자는 베어링의 동심도 오차이고 반응변수는 베어링 반력이다. 13개 모델의 비교분석 결과, 하우징 기하공차를 고려하면 베어링 반력이 증가되는 것을 확인하였다. 특히, 중간축과 출력축에 장착된 베어링들의 반력 증가율에 비해 입력축과 발전기축에 장착된 베어링들의 반력 증가율이 월등히 컸다. 따라서 본 연구 결과를 통해 베어링 설계 시에는 하우징 기하공차를 고려한 베어링 반력을 반영해야 한다는 것을 확인하였다.

1996년도 제35차 대한소화기학회 추계학술대회 / 호두까기 식도증에서 심리사회적 요소에 대한 연구

정우진(Woo Jin Chung),강영우(Young Woo Kang),박승국(Soong Kook Park) 대한소화기학회 1996 대한소화기학회지 Vol.28 No.1

IEEE 802.16e 네트워크에서 적응적 수면 모드 알고리즘을 통한 에너지 절약 방법

정우진(Woo Jin Jung),이태진(Tae-Jin Lee),정민영(Min Young Chung),정윤원(Yun Won Chung) 한국통신학회 2007 한국통신학회 학술대회논문집 Vol.2007 No.11