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오늘 본 자료
정대현,김주성,원동유,Chung, Dae-Hyun,Kim, Ju-Sung,Won, Dong-Yu 한국데이터정보과학회 2000 한국데이터정보과학회지 Vol.11 No.2
생존분석에서 널리 이용되고 있는 모형 중 하나인 와이블 모형에 대해 효율적인 모수 추정에 대해 연구하였다. 공변량을 포함하고 있는 와이블 모형의 모수를 추정하기 위하여 전 치료기간을 여러 단계로 나누어 최대우도법을 적용하는 분할법을 소개하였다. 실제의 자료를 적용하여 분할법과 비분할법으로 모수를 추정하여 비교한 결과 분할법의 효율성을 입증하였다. We study the efficient method to estimate the parameters for the Weibull model with covariates which occupies an important position in survival analysis. A treatment period may be divided by the stages of treatments under the different treatment arams. The piecewise method is considered to obtain the estimators of the parameters by maximum likelihood method. We explore the real data to show that the piecewise is more efficient than the nonpiecewise to estimate the parameters.
시스템 동바리 구조 안전성에 대한 최소 수평하중의 영향
정대현 ( Dae Hyun Chung ),김경윤 ( Gyeoung Yun Kim ),원정훈 ( Jeong Hun Won ) 한국안전학회(구 한국산업안전학회) 2015 한국안전학회지 Vol.30 No.5
This study examined the effects of the minimum horizontal load on the structural behaviors and safety of system supports. The minimum horizontal load was frequently ignored in the design of system supports even though the level of that load was specified in the code and guide in Korea such as ‘Standard Specification in Temporary Construction’ and ‘Guide to Installation of Shores for a Concrete Bridge’. To examine the effects of considering the minimum horizontal load, the finite element analysis were performed for various system supports. By varying installing parameters of system supports such as the vertical member spacing, the installation height, and the thickness of slab, the maximum combined stress ratios were estimated to investigate the structural safety of system supports. The results showed similar axial stress in vertical members but an increase in bending stress with a consideration of the horizontal load. The combines stress ratios are remarkably increased due to the consideration of the horizontal load. Consequently, the system supports, which were initially estimated to be safe when only the vertical loads were considered, were changed to be unsafe in most cases by the effects of the both the vertical and horizontal stresses. Therefore, the minimum horizontal load following the code and the guide is an essential load that could control the structural safety of system supports.
포켓형 시스템 비계 연결부의 연결상태를 고려한 회전강성 및 모멘트 강도 분석
장남권 ( Jang Nam-gwon ),정대현 ( Chung Dae-hyun ),원정훈 ( Won Jeong-hun ) 한국구조물진단유지관리공학회 2022 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.26 No.2
포켓형 연결부 형태를 가지는 시스템 비계를 대상으로 연결부의 연결상태에 따른 회전강성 및 모멘트 강도의 변화를 실험을 통해 분석하였으며, 주요 변수로 연결핀 타격 유뮤와 연결핀과 포켓의 이격 유무를 고려하였다. 일반적인 연결상태와 비교하여 망치로 타격하지 않은 연결부는 초기 회전강성, 이격된 연결부는 초기 회전강성과 모멘트 강도가 크게 감소하였다.
李萬燮,權寧赫,鄭大鉉,申瀅植 WHO COLLABORATING CENTRE FOR TRADITIONAL MEDICINE 1983 東西醫學硏究所 論文集 Vol.2 No.1
The purpose of this study was to investigate the effect of gargling with Hyung Ge Tong, an oriental medicine, on plaque and gingival indices. Sixteen dental students from Kyung Hee Dental School were randomly selected to be used as subjects for this experiment. Longitudinal study was performed by having the subjects gargle with Hyung Ge Tong for 4 weeks and without for the next 4 weeks. The subjects were told to performed regular oral hygienic care for the duration of the entire experiment. Measurements of plaque and gingival indices were taken before and after each 4 week periods. The results as follows: 1. The mean plaque and gingival indices for the experimental group using Hyung He Tong was 0.42 and 0.13. Although they wear lower than the control group, it was not shown to be statistically significant. 2. Plaque and gingival indices for the experimental group was significantly lower than control group at the beginning of the experiment. 3. Comparison of plaque and gingvial indices between facial and lingual showed no difference, while the index level for the right anterior region was higher than left anterior region. 4. There is some evidence that seem to indicate that gargling with Hyung Ge Tong may reduce plaque and gingival indices, however further study is needed.
폐경 여성에서 호르몬대체요법 후 유방 엑스선 사진의 변화
조수현,정창영,김봉수,정대현,조삼현,주경빈,류기영,황윤영 대한폐경학회 1998 대한폐경학회지 Vol.4 No.1
"Objectives: In the present retrospective study, we aimed to determine mammographic changes of breast parenchyme after hormone replacement therapy(HRT) in postmenopausal women. Methods: One-hundred fourty eight women were 'included into the study and devided into two groups.(HRT group: 129 women, No HRT group: 19 women) Prior to the start of HRT, an initial mammography was performed and repeated at 12 month intervals. HRT group included estrogen only(n=21), cyclic estrogen and progestin(n=52) and continuous estrogen and progestin(n=56) treated women. Mammograms were evaluated by two observers without knowledge of women's hormone treatment status. Results: Fifteen(12%) of 129 hormone treated women and 1(5.2%) of non-treated women developed increased parenchymal density during 1 year. Marginally significant increase in mammographic density after 1 year treatment was demonstrated according to age(6.6%, 12.2%, 30.0% in their fourties, fifties, sixties, respectively). Eleven percent of women showed increased density at the time of 12 month treatment but no one have increasment of density after 12 month of treatment in women whose menopausal duration was less than 5 years. A greater percentage of women treated with continuous combined estrogen-progestin showed increased mammographic density than cyclic combined estrogen-progestin treated women (71.4% vs 14.3%, p=0.001). Conclusions: An increase in mammographic density was demonstrated only in subjects undergoing continuous combined estrogen-progestin tteatment, in their sixties and less than one year treatment period. "
강득용,강주원,장혁순,정대현,이동화 순천향대학교 1981 논문집 Vol.4 No.3
Vascular tumors can be found in all parts of the nasal cavitied, the commonest being the hemangioma of the nasal septum. But overall incidence is rare. Clinically, its commonest symptoms are nasal obstruction and frequent nasal b1eeding. He-mangioma can be diagnosed by histologic study and it can be treated by surgical excision. Recently. the authors have experienced two cases of hemangioma of the nasal septum. We present these cases with a brief review of literatures.