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최돈찬,임시내 용인대학교 자연과학연구소 2001 自然科學硏究所論文誌 Vol.6 No.1
Photoperiod(length of light per day) is a major factor in determining sexual activity in golden hamsters. Long photoperiod(LP, ≥ 12.5 hours of light per day) maintains the sexual activities whereas short photoperiod(SP, ≤ 12 hours of light per day) suppresses them. The information of photoperiod is transmitted to the reproductive system by melatonin that is secreted from the pineal gland. Thus reproductive hormones are investigated in male golden hamsters that are housed in LP or SP and that are injected daily with melatonin in the morning or evening. Reproductive functions are active in the animals housed in LP and injected with melatonin in the morning and inactive in the animals housed in SP and injected in the evening. Paired testicular weights were markedly reduced in the sexually inactive animals. Serum FSH and LH levels were also lower in the sexually inactive animals than in the sexually active animals. When they were measured in the serum taken continuously from the same animal, both LH and FSH displayed pulsatile pattern in sexually active animals, but the pulsation was disappeared in sexually inactive animals. Moreover, the mean values of FSH and LH in regressed animals were much less. The histological examination of regressed testes showed reduction of tubular lumen diameter, interstitial space, and Leydig cell number. Taken together, the effects of photoperiod and melatonin treatment were reflected in reproductive endocrine system. The results suggest that their influence may be mediated by gonadotropin releasing hormone. Therefore, the impact of photoperiod(via melatonin) on GnRH neuronal system needs to be investigated.
High Performance Liquid Chromatography를 이용한 멜라토닌 측정
최돈찬,임시내 龍仁大學校 2001 용인대학교 논문집 Vol.19 No.-
Melatonin is a pineal hormone that transduces the photoperiodic information into neuroendocrine system. It acts as a regulator of seasonal reproduction, a biological clock to time circadian rhythmicity, an inhibitor on the growth of tumor and cancer cells, and a controller of cardiovascular function. It also shows anti-aging and life-prolonging effects and a supportive role in the immune system. Melatonin was measured using a conventional HPLC apparatus. Although the sensitivity is low compared to the radioimmunoassay or HPLC with fluorescence or electrochemical detector, these results could be applied to the blood samples withdrawn from the living organisms to which a large amount of melatonin was administered. The method used in this study is simple, convenient, and rapid without need of any further equipments.
최돈찬,우대균,임시내 한국환경생물학회 2002 환경생물 : 환경생물학회지 Vol.20 No.3
광주기(하루 중 빛의 길이)는 골든 햄스터의 생식을 조절하는 주된 요인이다. 광주기 정보는 멜라토닌을 통하여 생식 내분비계로 전달된다. 따라서 멜라토닌이 생식에 미치는 효과를 여러 광주기에 노출시킨 햄스터에서 조사하였다. 단주기(하루 중 12시간 이하의 조명)에 노출시킨 동물들과 저녁에 멜라토닌을 주사한 동물들의 정소 무게는 현저하게 줄어들었으나, 장주기 (하루 중 12.5시간 이상의 조명)에 유지된 동물과 오전에 멜라토닌을 투여한 동물들의 정소 무게는 줄어들지 않았다. 퇴화된 정소를 조직학적으로 조사한 결과, 세정관 직경이 감소되었고,세정관내 세포수가 두드러지게 줄어들었다. 또한 생식 능력이 퇴화된 동물의 혈중 여포자극호르몬과 황체호르몬의 수준도 생식 능력을 보유하고 있는 동물에 비해 뚜렷하게 감소하였다. 멜라토닌 수용체가 역전사 polymerase chain reaction으로 등정되었고 조직특이성 또한 조사하였다 동정된 멜라토닌 수용체는 309 염기였으며,시상하부와 뇌하수체를 포함하는 다양한 장기에서 발현되었다. 생식을 조절하는 핵심 물질인 gona-dotropin releasing hormone (GnRH) 유전자의 발현 또한 동정되었다. 그러나 멜라토닌 처리와 광주기 처리는 GnRH유전자 발현에 영향을 미치지 않았다. 종합하면, 광주기의 효과는 멜리토닌을 경유하여 발휘되며,멜라토닌은 GnRH유전자의 발현보다는,생성된 GnRH의 분비에 영향을 미쳐 생식내분비계에 간접적으로 작용함을 알 수 있었다. Photoperiod (length of light per day) is a major factor in regulating reproductive function in golden hamsters. The information of photoperiod is transmitted to the reproductive endocrine system by melatonin. Thus the effects of melatonin are investigated in male golden hamsters exposed to photoperiods. Paired testicular weights were markedly reduced in the animals housed in short photoperiod (SP, ??12hours day^-1) and injected with melatonin in the evening, but not in long photoperiod(LP, ??12.5 hours day^-1) and injected with melatonin in the morning. The histological examination of regressed testes showed reduction of tubular lumen diameter including the numbers of cells and Leydig cell number. The mean values of both follicle stimulating hormone (FSH) and luteinizing hormone (LH) were also lowered in the sexually inactive animals than in the sexually active animals. Melatonin receptor was identified by reverse-transcription polymerase chain reaction (RT-PCR) and its expression was examined in various tissues to scrutinize the action site of melatonin. It turned out 309 nucleotides and was definitely expressed in hypothalamus and pituitary including spleen, retina, and epididymis. And gonadotropin releasing hormone (GnRH) gene, which is a key element in regulating reproduction, was identified by RT-PCR but the expression of GnRH was not modified by the treatment of melatonin. Taken together, photoperiod via melatonin indirectly affects reproductive endocrine system, possibly through the release of GnRH, not the synthesis of GnRH.
오병환(Oh Byung Hwan),임시내(Lim Si Nae),최영철(Choi Young Cherl) 한국철도학회 2002 한국철도학회 학술발표대회논문집 Vol.- No.-
The design of sleeper in high-speed railway turnouts is complicated and time-consuming because the length and loading position of sleepers change continuously along the turnout line. It is, therefore, necessary to develop an automated design program which can design automatically the PSC sleepers in turnout region. In this study, a computer program for automatic design of turnout sleepers was developed based on graphic user-interface(GUI) environment. The structural analysis is performed considering the varying loading position of vehicular wheels. The sleepers are treated as located on elastic supports. The user can choose the desirable shape of sleepers before starting the detail design. The present study allows more realistic and automatic design of PSC sleepers in high-speed railway turnouts.
프리텐션 공법의 PC부재의 전달길이 해석 및 예측에 관한 연구
오병환 ( Oh¸ Byung-hwan ),임시내 ( Lim¸ Si Nae ),최영철 ( Choi¸ Young-chul ) 한국구조물진단유지관리공학회 2002 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.6 No.2
In pretensioned concrete structures, bond between prestressing steel and concrete is an essential component to ensure the integrity of a pretensioned member. The anchorage and development of the prestressing force depend exclusively on bond. The first purpose of this study is to investigate the characteristics of bond and transfer length between pretensioned steel and concrete. The second is to establish the realistic equation of transfer length considering essential variables. In this study. bond-slip relationship is determined from experiment results of stress increase in steel and strain in concrete at transfer. And finite element analysis are carried to determine transfer length considering various variables(strand type, concrete strength, concrete cover, prestressing force) by using bond-slip equation.