• 농업과학연구
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• 제42권3호
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• pp.245-251
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• 2015

Records of 490,767 cows collected from 1990 to 2012 by dairy herd milk test of National Agriculture Cooperative Federation The pedigree of dairy cattle were provided by Korea Animal Improvement Association. The data were used to analyze the longevity of dairy cows with the life traits such as days in milk, number of lactation, productive life, and life span. The data were also used to investigate genetic relationship of these longevity traits with profitability of dairy cows, including heritability and genetic correlation. The profitability was calculated with simulation of milk income and production costs for individual cows. Days in milk among the traits had -0.287, -0.572 and -0.536 of genetic correlation with number of lactations, productive life and lifespan, respectively. The heritabilities of life span, number of lactations, productive life, and days in milk were found to be 0.045, 0.047, 0.059 and 0.081, respectively. Genetic correlations of profit with productive life, number of lactations, and days in milk were identified as 0.072, 0.080, 0.098 and 0.101. These results suggested that days in milk was most desirable traits to represent longevity of Holstein dairy cattle. In general, since longevity and profitability were close genetic relationship each other, genetic improvement of longevity is necessary for better profitable cows.

• Journal of Communications and Networks
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• 제7권3호
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• pp.325-336
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• 2005

Mobile ad hoc networks (MANET) are composed of moving wireless hosts which, within range of each other, form wireless networks. For communication to occur between hosts that are not within each other's range, routes involving intermediate nodes must be established; however, since the hosts may be in motion, a host that was part of a route may move away from its upstream and downstream partners, thus breaking the route. In this paper, we propose anticipated route maintenance (ARM) protocol with two extensions to route discovery based routing scheme: Extend the route when nodes on a link move apart from each other and they have common neighbor that can be 'inserted' in the path, and shrink route when a node discovers that one of its neighbor which is not the next hop is also on the same route several hops later on. By utilizing only local geographic information (now a part of some route finding algorithms), a host can anticipate its neighbor's departure and, if other hosts are available, choose a host to bridge the gap, keeping the path connected. We present a distributed algorithm that anticipates route failure and performs preventative route maintenance using location information to increase a route lifespan. The benefits are that this reduces the need to find new routes (which is very expensive) and prevents interruptions in service. As the density of nodes increases, the chance to successfully utilize our route maintenance approach increases, and so does the savings. We have compared the performance of two protocols, pure dynamic source routing (DSR) protocol and DSR with ARM. The simulation results show how ARM improves the functionality of DSR by preventing the links in the route from breaking. Packets delivery ratio could be increased using ARM and achieved approximately $\100%$ improvement. The simulations clarify also how ARM shows a noticeable improvement in dropped packets and links stability over DSR, even though there is more traffic and channel overhead in ARM.

• 한국기계가공학회지
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• 제14권5호
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• pp.42-49
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• 2015

In this study, the multi-disk of a high-pressure drop control valve is designed and manufactured. Then, the flow rate and high-pressure drop of fluids flowing in the high-pressure drop control valve is CAE/CFD. This study involves numerical analysis for the Zambil offshore project of a high-pressure drop control valve. ANSYS used a solver for offshore structures analysis. A high-pressure drop control valve, which transforms the power transfer of a system by reducing the inlet pressure of 345bar to the outlet pressure of 112bar, is a fundamental component in the offshore process. This study not only analyzes the relation between pressure drop and fluid velocity in a trim by using fluid analysis, but also examines the possibility of cavitation in a valve in addition to the plot for the extension of lifespan. It is demonstrated that the pressure drop from 345bar to 112bar is more feasible in the presence of the trim, which can induce a continuous and diminutive pressure drop in order to prevent cavitation in a high-pressure drop control valve.

• 한국가정과학회지
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• 제7권3호
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• pp.83-106
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• 2004

As the lifespan has been expanded, the marital relationship later in life is getting more important. This study is to find out what the demand for the education of marital couples to improve this relationship. The results can be used as basic data to develop educational programs for elder couples. The results of this study are as follows. 1. Couple role according to socio-demographic variables can be divided into traditional and modern roles. And these variables are shown to be significant in couple role. 2. Need for the education of married couples according to socio-demographic variables. In case of spouses having shorter marriage period, religion, and a nuclear family, and doing social activities, the necessity of education is recognized highly. Those who have a spouse with good health and social activities have experienced a chance to attend the educational program. It is thought that health and social activities have much to do with active living attitude. In case of old age, it can be thought that they don't feel the necessity because they have lived a decent life for a long time. It is just that it comes from the fixed ideas of elder couples who had to spend only a short time with their spouses. That is what elder couples have to overcome. They tend to think that the relationship between the family is more important than that of spouses, and they put family relationship before the quality of their own lives. 3. Influence of the need for the education of married couples according to their role. As their role are becoming modern and their mutual trust, affinity, and cohesion are getting more important, the education of married couples and the experiences of communication and participation in the educational program are thought to be more necessary.

• 디지털융복합연구
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• 제12권2호
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• pp.271-276
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• 2014

무선 센서 네트워크의 수명 및 성능은 각 센서 노드들의 에너지 효율과 밀접한 관련이 있다. 본 논문에서는 센서 노드의 에너지 효율을 높이기 위해 센서 노드의 동작 상태를 정상, 절전, 및 비활성 모드로 나눈다. 정상 모드로 동작하는 센서 노드는 정상 주기로 센싱 및 데이터 전송을 하지만, 절전 모드에서는 그 주기를 늘임으로써 에너지 소비를 줄인다. 센싱 및 데이터 전송을 하지 않는 비활성 모드에서는 에너지 소비가 최소화된다. 또한, 제안 알고리즘은 센싱 데이터가 이전의 값과 동일할 경우 전송을 하지 않음으로써 불필요한 에너지 소비를 줄일 수 있다. 제안 알고리즘은 Tiny OS 기반의 ZigbeX 플랫폼에 구현되었으며, NS-2를 사용하여 그 성능을 분석하였다. 성능 분석결과 제안 알고리즘이 전체 센서 노드의 에너지 소비 및 그 표준편차를 효율적으로 줄임으로써 무선 센서 네트워크의 수명을 향상시킬 수 있음을 확인하였다.

• 한방안이비인후피부과학회지
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• 제17권1호
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• pp.16-33
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• 2004

In Oriental medicine, aging is just a natural process like change of seasons. Ancient Oriental people accepted it as a natural thing to be growing older and to die at last. The science of aging has advanced dramatically. In the last 2 decades, advances in genetics and molecular biology have led to extraordinary new understandings in how cells age, how apoptosis programs cells to die, and how neuroendocrinology plays a role in the lifespan of organisms. Today, the matter of primary concern about aging is a cellular and mitochondrial damage of human body induced by reactive oxygen species(ROS). The skin aging can be divided into two areas, intrinsic(chronologic)-aging and photo-aging. There are lots of photo damage about skin aging. The skin is increasingly exposed to ultraviolet(UV) irradiation in life. Therefore, the risk of photo-oxidative damage of the skin induced by reactive oxygen species(ROS) has increased substantially. Nowadays, many people believe that they can stop or at least delay the process of aging. There are lots of treatments that promise to slow the process of aging and the associated ailments. Many of these treatments, for example, exercise, Vit E, Vit C therapy, hormone therapy, restrict diet, are gradually being subjected to clinical trials. But in spite of all efforts, researches and investigations, there is no single method or treatment which is revealed to be truly effective for delaying progress of aging. Every methods insisted on effect for delaying aging process, has its dark side. All we can do is just keeping ourself healthy until the time of death.

• 한국도로학회논문집
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• 제14권6호
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• pp.25-35
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• 2012

PURPOSES : Hollows are easily made, and bearing capacity can be lowered near underground structures because sublayers of pavement settle for a long time due to difficult compaction at the position. If loadings are applied in this condition, distresses may occur in pavement and, as the result, its lifespan can decrease due to the stress larger than that expected in design phase. Although reinforced slab is installed on side of box culvert to minimize the distresses, length of the reinforced slab is fixed as 6m in Korea without any theoretical consideration. The purpose of this paper is investigating the behavior of concrete pavement according to the cover depth of the box culvert ad the length of the reinforced slab. METHODS : The distresses of concrete pavement slabs were investigated and cover depth was surveyed at position where the box culverts were located in expressways. The concrete pavements including the box culverts were modeled by finite element method and their behaviors according to the soil cover depth were analyzed. Wheel loading was applied after considering self weight of the pavement and temperature gradient of the concrete pavement slab at Yeojoo, Gyeonggi where a test road was located. After installing pavement joint at various positions, behavior of the pavement was analyzed by changing the soil cover depth and length of the reinforced slab. RESULTS : As the result, the tensile stress developed in the pavement slab according to the joint position, cover depth, and reinforced slab length was figured out. CONCLUSIONS : More reasonable and economic design of the concrete pavement including the box culvert is expected by the research results.

• 전자공학회논문지 IE
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• 제43권3호
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• pp.22-27
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• 2006

본 논문에서는 새로운 제어방식과 평면 변압기(planar transformer)를 이용한 자동차용 35W급 메탈헬라이드 램프용 고효율 전자식 안정기의 제어시스템을 제안하였다. 본 논문에서는 밝기, 연색성, 광효율, 수명 등에서 기존의 할로겐 램프에 비해 우수한 특성을 가지고 있지만 복잡한 과도특성을 가지고 있는 메탈헬라이드 램프를 자동차에 적용하기 위해 마이크로컨트롤러에 의한 디지털 제어방식을 전자식 안정기에 적용하여 램프 요구조건 및 주변 환경에 최적으로 적용할 수 있도록 전자식 안정기를 설계하였다. 또한, 자동차의 밧데리 입력전압에 따라 안정기 컨버터(Flyback Converter)의 스위칭 주파수를 가변하여 안정기의 효율증대를 도모하였고, 컨버터의 고주파 스위칭 변압기를 평면 형태로 설계하여, 기존의 고주파 변압기에 비해 손실, 무게 등의 절감과 전체적인 크기를 축소하여, 밧데리라는 한정된 에너지와 한정된 공간을 갖는 자동차에서 효율적인 전력제어를 실현하였다. 개발된 안정기에 대한 동작특성을 실험을 통해 확인하였다.

• 전자공학회논문지
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• 제49권11호
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• pp.193-198
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• 2012

LED를 고효율 및 고수명으로 동작시키기 위해 장착되는 LED 컨버터는 정전압 및 정전류 구동을 함으로서 LED에 제공되는 전력을 일정한 전압과 전류 값으로 유지하여 LED를 동작시키게 한다. 하지만 이러한 LED 컨버터는 LED의 과열로 인해 전압이 떨어지거나 전력 선로의 손상으로 인한 과전압 혹은 회로 이상에 따른 과전압 발생 시에도 여전히 일정 전압 및 전류를 계속 LED에 공급하게 된다. 결국 LED에 과도한 전압이나 전류가 유입되어도 LED는 계속적으로 발광하기에 결국 파손되는 문제가 발생하게 된다. 본 논문에서는 LED의 과열이나 전압강하 등의 이유로 과전류가 발생하면 PWM 회로를 정지시키고 일정 전류 이하에서만 PWM 회로가 동작하도록 하며 PWM 회로에서 과전압이 발생되는 경우 회로의 구동을 일시 정지시켜 LED가 과전류와 과전압에 의해 파손되는 것을 방지하는 피드백 회로를 제안한다.

• 한국멀티미디어학회논문지
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• 제10권3호
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• pp.348-357
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• 2007

제한된 전원으로 동작해야 하는 센서 노드의 수명 연장을 위하여, 에너지 효율적인 센서 노드의 동작에 대한 많은 연구가 진행되었다. 그들 중에는 주기적으로 무선 송수신 모듈을 활성화 / 비활성화 하면서 정보전달을 위하여 인접 노드가 깨어나는 시점에 대한 정보를 필요로 하는 기법들이 존재한다. 클락 동기는 이러한 기법들에서 무선 송수신 모듈의 활성화 / 비활성화 스케줄링을 위하여 필수적인 요소이다. 본 논문에서는 센서 망에서 전역 클락 동기를 위하여 제안된 비동기 평균 알고리즘을 기반으로 주기적인 무신 송수신 모듈 활성화 / 비활성화 기법에서의 클락 동기 방법을 제안한다. 구체적으로 본 논문은 (1) 초기 자율적인 망 구성 시점에 필요한 신속한 클락 동기 방법과 (2) 에너지 소모를 최소화한 주기적인 클락 동기 방법 및 (3) 두 가지 동기 방법들 간의 전환 시점 판단 방법을 제안한다. 시뮬레이션을 통하여 제안한 방법의 클락 오차 범위와 교환되는 메시지 수를 분석한다.