• 한국경영과학회지
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• 제32권2호
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• pp.141-147
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• 2007

We consider a GI/M/1 queue with vacations such that the server works with different rate rather than completely stops working during a vacation period. We derive the transform of the joint distribution of the length of a busy period, the number of customers served during the busy period, and the length of the subsequent idle period.

• 한국패류학회지
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• 제22권1호
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• pp.39-49
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• 2006

Ultrastructure of germ cell differentiation during supermatogenesis and the reproductive cycle in male Patinopecten yessoensis was studied by histological and cytological observations. The gonadosomatic index (GSI) in males rapidly increased and reached a maximum in April when seawater temperature gradually increased. Then the GSI gradually decreased from May through July when spawning occurred. Accordingly, monthly changes in the GSI in males coincided with testicular maturation and spawning periods. The sperm morphology of P. yessoensis belongs to the primitive type and showed general characteristics of external fertilization species. The head of the spermatozoon is approximately $3.50{\mu}m$ in length: the sperm nucleus and acrosome are approximately $2.90{\mu}m\;and\;0.60{\mu}m$ in length, respectively. The nuclear type of the spermatozoon is vase in shape, and the acrosome is cone type. The axoneme of the tail flagellum consists of nine pairs of microtubules at the periphery and a pair of central microtubules in the center The satellite body (which is formed by the centriole) and four mitochondria appear in the middle piece of the spermatozoon. The spawning period was from April through July and the main spawning occurred from May to June when seawater temperatures gradually increased. The reproductive cycle of this species can be classified into five successive stages; early active stage (September to November), late active stage (October to March), ripe stage (February to August), spawning stage (April to July), and spent/inactive stage (July to November).

• 대한교통학회지
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• 제23권7호
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• pp.43-52
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• 2005

실시간 신호제어군의 결합 및 분리를 통한 실시간 연동신호교차로군 조절은 최근에 강조되고 있는 첨단교통신호제어시스템의 기능 중 하나이다. 필요에 따라 연동축 및 연동방향을 능동적으로 조절하는 과정에서 신호제어군의 실시간 분리 결합 상황이 발생하며, 이때 필수적으로 옵셋을 재조정을 위한 '옵셋전이시간'이 소요된다. 이 때 '옵셋전이시간'이 필요이상 긴 경우 비효율적인 신호운영변수가 장시간 적용됨으로 인하여, 필요이상 짧은 경우 갑작스런 신호시간 변화에 따른 교통흐름 장애 (turbulence)로 인하여 해당 구간 신호제어 운영 효율성이 저하될 수 있다. 현재의 국내 실시간 신호제어시스템은 3주기에서 5주기에 걸쳐 '옵셋전이시간'을 적용할 것을 개략적으로 권고하고 있으나 해당분야에서의 공학적 연구가 미비하다. 본 연구에서는 네 가지 다른 옵셋전이시간(한 주기길이, 두 주기길이, 세 주기길이, 네 주기길이)를 활용하는 네 가지 다른 옵셋전이방법의 성능을 CORSIM 모의실험 환경에서 CORSIM RTE 기능을 이용하여 분석하고 비교하였다. 설정된 총 15가지 상이한 교통소통 상황을 토대로 다양한 무작위난수를 적용하는 모의실험을 수행하며 수집된 평균 차량지체자료를 통계 분석한 결과 한 주기 길이 옵셋전이시간이 본 연구에서 설정된 모든 교통상황에서 기타 옵셋전이시간보다 우수하거나(낮은 지체도) 적어도 동일한 것으로 분석되었다. 본 연구는 한 주기 '옵셋전이길이' 적용을 옵셋전이 적용지침으로 사용할 것을 제안한다.

• 대한수의학회지
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• 제32권2호
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• pp.259-265
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• 1992

A study was conducted to improve the reproductive performance of Korean native goats. The length of estrous cycle and plasma progesterone concentrations during each cycles were determined by both radioimmunoassay and estrus behaviours, and the results were used in the early pregnancy diagnosis. The estrous cycles were classified into the short(l8 days or shorter, average 16.7 days), normal(19 to 22 days, average 20.9 days) and long(23 days and longer, average 23.8 days)cycle. The average length of the 19 estrous cycles was 20.8 days. Plasma progesterone concentrations in 12 normal cycles were the lowest(0.10 ng/ml) at estrus, remained high from 6 to 16 days(range : 4.43~7.93 ng/ml) and drastically decreased thereafter to reach minimal concentrations at the next estrus. Plasma progesterone concentrations were measured for early pregnancy diagnosis at 0, 10 and 20 days after mating in the 12 Korean native goats. Plasma progesterone concentrations in the pregnant goats at 20 days after mating were significantly higher than in the non-pregnant goats(p<0.001). Of the 12 goats, 10 were confirmed pregnancy by both progesterone concentrations and kidding. The accuracy of the pregnancy diagnosis based on plasma progesterone concentrations was 100% for positive as well as for negative.

• 한국수산과학회지
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• 제30권1호
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• pp.132-138
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• 1997

동해안 한해성 조개인 북방대합의 자원 증대를 위한 기초 자료를 얻기 위하여 1994년 3월부터 1995년 5월까지 주로 조직학적 방법에 의해 생식소의 발달과정과 생식주기를 조사하였다. 북방대합은 자웅이체로서, 생식소는 해부학적으로 소화맹낭과 족부 근육 사이에 위치하였다. 비만도는 1994년 6월에 0.19로 가장 높았으며 11월에 최소값을 보였다. 생물학적 최소형은 각장 50.0mm였으며, 80.0mm 이상의 대형개체에서도 $10\%$ 미만의 성적으로 미분화한 개체가 관찰되었다. 성숙한 난모세포의 크기는 $50\~60{\mu}m$였으며, 성숙기의 정소에서 정소란이 관찰되었다. 북방대합의 생식주기는 분열증식기 ($10\~1$월), 성장기 ($2\~4$월), 성숙기 ($4\~6$월), 산란기 ($6\~7$월) 및 휴지기 ($8\~9$월)의 연속적인 5단계로 구분되었다.

• 대한한방부인과학회지
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• 제25권1호
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• pp.56-69
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• 2012

Objectives: This study was conducted to investigate the relationship between menstrual conditions and items of health checkup examinations in female university students for prediction of reproductive health. Methods: Data from the 2011's medical examination participants(990 students among total 1,699 students) of ${\bigcirc}{\bigcirc}$ University University in Korea were analyzed for this study. Menstrual condition, Sa-sang constitution and other surveys were checked through self-administered questionnaire, health checkup were measured anthropometric variables, CBC, B/C and U/A. Results: In the 46.4% of total participants appeared menstrual disorder of menstrual cycle or menstrual amount, the irregular period of menstrual cycle have a influence on menstrual amount. stress was relatively heavy factor of causing irregularity of menstrual cycle and amount, RBC, cholesterol, ABO type and Sa-sang constitution had some connection with menstrual amount. Conclusions: Among the items of health checkup examinations, stress, RBC, cholesterol, ABO type and Sa-sang constitution were related with the change of menstrual cycle and amount.

• 콘크리트학회논문집
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• 제22권2호
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• pp.263-271
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• 2010

이 연구는 국내에서 생산되고 있는 철근이 반복하중을 받는 경우의 파괴 특성에 대한 검증을 목적으로 한다. 이 논문은 철근콘크리트 하부구조(파일과 교각)에 배근된 축방향 철근에 대한 저주파 피로 거동을 다루었다. 전체 81개의 철근 실험체에 대하여 변형률 진폭에 따른 반복 축방향 변형률 제어 방식으로 저주파 피로 실험을 수행하였다. 실험 변수는 인장변형률과 압축변형률의 비율, 축방향 철근의 항복강도, 철근지름에 대한 철근길이의 비율, 철근의 크기와 변형률 진폭으로 선택하였다. 이 논문에서 실험 결과에 따른 저주파 피로 거동과 저주파 피로 수명을 분석하였다.

• Journal of Astronomy and Space Sciences
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• 제30권2호
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• pp.101-106
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• 2013

The length of solar cycle 23 has been prolonged up to about 13 years. Many studies have speculated that the solar cycle 23/24 minimum will indicate the onset of a grand minimum of solar activity, such as the Maunder Minimum. We check the trends of solar (sunspot number, solar magnetic fields, total solar irradiance, solar radio flux, and frequency of solar X-ray flare), interplanetary (interplanetary magnetic field, solar wind and galactic cosmic ray intensity), and geomagnetic (Ap index) parameters (SIG parameters) during solar cycles 21-24. Most SIG parameters during the period of the solar cycle 23/24 minimum have remarkably low values. Since the 1970s, the space environment has been monitored by ground observatories and satellites. Such prevalently low values of SIG parameters have never been seen. We suggest that these unprecedented conditions of SIG parameters originate from the weakened solar magnetic fields. Meanwhile, the deep 23/24 solar cycle minimum might be the portent of a grand minimum in which the global mean temperature of the lower atmosphere is as low as in the period of Dalton or Maunder minimum.

• 설비공학논문집
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• 제21권3호
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• pp.131-139
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• 2009

The simulation of refrigeration cycle is important since the experimental approach is costly and time-consuming. The present paper focuses on the simulation of a refrigeration cycle equipped with a capillary tube-suction line heat exchanger(SLHX), which is widely used in small vapor compression refrigeration systems. The present simulation is based on fundamental conservation equations of mass, momentum, and energy. These equations are solved through an iterative process. The non-adiabatic capillary tube model is based on homogeneous two-phase flow model. This model is used to understand the refrigerant flow behavior inside the non-adiabatic capillary tube. The simulation results show that both of the location and length of heat exchange section influence the coefficient of performance (COP).

• Nuclear Engineering and Technology
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• 제29권6호
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• pp.488-499
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• 1997

The measurements of the moderator temperature coefficient (MTC) are performed to demonstrate that the calculational model produces results that are consistent with the measurements. Since negative MTC is also a technical specification value that may limit the cycle length, it is important to measure it as accurately as possible. In this report, preferred choice of test method depending on the time in cycle, best power indication and temperature definition in MTC calculation were determined based on the MTC test results taken during initial startup testing and at 2/3 cycle burnup in the Yonggwang nuclear power plant. The results show that the ratio and rodded methods provided good agreement with the predictions during initial startup testing. However, near end-of-cycle the depletion method gives better results, and so is suggested to be used in the MTC measurements at 2/3 cycle burnup. The use of primary Delta T power as a power indicator in the MTC calculations is highly advisable since it responds with good consistent results very quickly to changes unlike secondary calorimetric power. For the appropriate temperature definitions used in the MTC calculations, it is considered that the arithmetic average temperature measured simply by inlet and outlet thermocouples is preferred. Although volumetric average temperature provides better results, the improvement is not sufficient to compensate for the simplicity of calculations by arithmetic average temperature.