• 설비공학논문집
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• 제1권2호
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• pp.116-127
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• 1989

Research on reheating cooling cycle and its practical application have been made to prevent unequalized distribution of temperature and humidity of room due to lack of supply air volume and dewdrops on supply diffusers to be taken place as a result of lower temperature of supply air than that of dew point of room air in cooling cycle of constant air volume, single duct, single zone and draw-through fan type. In view of the fact that human body is insensitive to humidity, it is possible not only to construct the complete non-reheating cooling cycle by increasing the humidity point allowable with the deduction of occupant's sense of pleasantness minimizing, but also to get cooling cycle decreasing the reheating quantity if the humidity exceeds the point allowable. In addition, it is possible to save maximum 8% in electric energy for cooling in cooling system by constructing non-reheating cooling cycle instead of reheating cooling cycle and by increasing the relative humidity of room from 50% to 65% in case efficiency and air pressure of cooling system are low. It is also possible to get an optimum cooling cycle by determining the room humidity in consideration of pleasantness of occupants and conservation rate of electric energy if the cooling capacity, efficiency and total pressure of cooling equipment are fixed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.521-522
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• 2009

• 대한지구과학교육학회지
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• 제9권2호
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• pp.186-198
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• 2016

연구의 목적은 예비 지구과학 교사들이 이해하고 있는 암석 순환의 구성요소와 과정에 대해 밝히는 것이다. 남부 지역에 소재한 사범대학교 2학년에 재학하면서 지구과학 수업을 수강하는 25명의 예비교사들이 연구대상으로 선정되었다. 암석 순환의 구성요소들을 구조적으로 배열하고, 순환 방향을 화살표로 표시하고, 순환 과정에 대해 서술하는 방법을 적용하였다. 예비교사들이 이해하는 암석순환의 구성요소는 마그마, 화성암, 변성암, 퇴적물, 퇴적암의 5가지로, 순환의 과정은 20가지로 표현되었다. 순환의 유형은 선형, 삼각형, 원형, 복합형의 4가지 기준으로 분석되었으며, 일부 예비교사들은 순환의 고리를 완성하지 못하거나 한 방향의 단순한 순환 구조로 시스템적이지 못한 이해를 표출하였다. 암석 순환은 역동성과 복잡성으로 특징되는 지구계 교육의 주제로서 중요한 의미가 있다.

• 한국수소및신에너지학회논문집
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• 제11권4호
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• pp.189-202
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• 2000

$AB_2$ type Zr-based Laves phases alloys have been studied for potential application as a negative electrode in a Ni-MH battery. The $AB_2$-type electrodes have a much higher energy density than $AB_5$-type electrodes per weight, however they have some disadvantages such as poor activation behavior and cycle life etc. Nonetheless, the $AB_2$-type electrodes have been studied very extensively due to their high energy density. In this study, in order to develop the cycle life, the Mn of $AB_2$ alloy composition was substituted partially by Mo. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The alloy powder was used below 200-325 mesh for experiments. The structures and phases of the alloys were analyzed by XRD, SEM and EDS, and measured the curve of a pressure-composition isotherms. The electrodes were prepared by cold pressing of the copper-coated(25 wt%) alloy powders, and tested by a half cell. The results are summarized as follows. The cycle life was improved with the increase of Mo amount in $Zr_{1-x}Ti_xV_{0.4}Ni_{1.2}Mn_{0.4}Mo_y$(x=0.3, 0.4) and the activation was faster, whereas the discharge capacity decreased.

• 대한수의학회지
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• 제32권3호
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• pp.281-293
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• 1992

Classification of the cycle of seminiferous epithelia into 12 stages by the morphological changes in acrosomal system and evaluation of the relative frequency of stages and the cell association were histologically performed in the mature Korean native Jin-do dogs. The results were summarized as follows; 1. The minimum number of type A spermatogonia averaged 1.01 at stages I, while maximum number averaged 2.47 at stages XII. Some type A spermatogonia divided at stage XII to produce the type intermediate(IN) spermatogonia at the following stage I. The type IN spermatogonia divided at stage IV to produce the type B spermatogonia at stage V. 2. The type B spermatogonia divided at stage VI to produce the preleptotene primary spermatocytes at stage VII. The secondary spermatocytes observed at stage XII. The secondary spermatocytes observed at stage XII divided to give rise to the round spermatids at the following stage I. The numbers of the first spermatocytes and spermatids were almost constant, respectively, through all the cycles of seminiferous epithelium. 3. The acrosomal vesicle was invaginated to occupy one third to half of spermatid nucleus at the cap phase, which was different from that of rodent and ruminant spermatid nuclei. 4. The relative frequencies of stages I to XII of seminiferous epithelia cycle were 10.34, 4.84, 5.03, 8.22, 10.86, 6.63, 6.42, 18.88, 10.17, 6.18, 7.62% and 4.81%, respectively.

• 전기화학회지
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• 제20권4호
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• pp.61-66
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• 2017

The cycle performance of Ti-Si alloy anode material for Li-ion batteries has been investigated as a function of loading level of electrode using a nodule type of substrate, in which the current collector of flat foil is also used for comparison. The Ti-Si alloy powders are prepared by mechanical alloying method. The electrodes with the nodule type of current collector exhibit enhanced cycling performance compared to those using the flat foil because the alloy particles are more strongly adhered to substrate and the stress caused by lithiation and delithiation reaction can be effectively relaxed by nodule-type morphology. It appears, however, that the cycle performance is critically dependent on the loading level of electrode, even when the nodule type of current collector is applied. With high loading level, cracks are initiated at surface of electrode due to a steep stress gradient through the electrode thickness during cycling, leading to capacity fading.

• 한국산학기술학회논문지
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• 제20권7호
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• pp.1-7
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• 2019

본 논문은 침수피해 방지를 위한 기존의 우수배제시스템의 한계점을 극복하기 위해서 신규 개발된 친환경 수로형 우수배제시스템을 비교 및 분석하고, 기존 시스템 대비 장점을 정량화하기 위한 통합평가지표의 개발 및 적용에 관한 연구이다. 이에 전과정평가(Life Cycle Assessment, LCA)의 개념을 적용하여 각 공정별 필요물량과 비용을 산정하여 비교하였고, 또한 탄소배출량을 각 과정별로 산정하여 고려하는 통합평가지표를 개발하여 각각의 기술에 적용하였다. 그 결과 원형 집수시스템에 비해 전 과정에 걸쳐 비용이 53 %, 측구 집수시스템에 비해 63 %가 절감되는 것으로 분석되었다. 또한 통합평가지표 적용결과, 기존 기술대비 수로형 집수시스템을 평가한 결과 건설공사 분야를 제외한 나머지 4가지 분야(건설자재, 운용 및 유지관리, 해체, 폐기)에 있어서 80 % 이상의 높은 점수로 평가되었다. 본 연구에서 개발된 평가지표를 경기도 안양현장과 인천 청라현장에 적용하여 기존 기술대비 약 35 ~ 100 % 개선된 높은 점수로 향상되어 개선효과를 입증하였고 동시에 적용성을 확보하였다.

• 설비공학논문집
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• 제16권12호
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• pp.1167-1174
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• 2004

The method to consider gravity effect on the performance of a condenser is developed, and a simple condenser having 'nU' type two circuits is analyzed. Each circuit has the same length and inlet air-side operational conditions. The only difference between two circuits is the direction of refrigerant flow, which is exactly opposite each other between the upper 'n' type circuit and the lower 'U' type circuit. It is shown that the gravity makes the distribution of refrigerant flow uneven in the two circuits at lower refrigerant flow rates; heat transfer rate also becomes uneven. Moreover, much of the refrigerant exists as liquid state in the circuit having low refrigerant flow rate, which will make the cycle balance unstable in the refrigeration cycle system like a heat pump.

• 상하수도학회지
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• 제11권2호
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• pp.50-64
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• 1997

Life cycle assessment (LCA) on total sewage sludge treatment system from thickening to incineration and melting was performed for estimating global environmental impact as $CO_2$. In general, the life cycles of actual treatment facilities consist of construction, operation and dismantlement. In this study, the amount of $CO_2$ produced from both whole and each life cycle step of currently used unit sludge treatment processes were calculated by inventory analysis. In addition, in the all processes investigated in this study, individual $CO_2$ production unit (CPU), i.e. total produced $CO_2$ by treating a unit weight of sludge was also calculated. By using the CPU matrix of the unit processes, it was possible to simulate the $CO_2$ production for any type of complex-system as well as to trace a dominant cause of $CO_2$ production in each process. Four selected alternatives examined here, each involve the same disposal way but differ substantially in the $CO_2$ exhaust.

• 대한지역사회영양학회지
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• 제7권2호
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• pp.188-198
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• 2002

This study was conducted to compare families eating-out behavior in relation to family life cycle in order to provide basic information on nutritional education about eating-out. The data were collected by the survey method from 440 families who lived in apartment complexes in Kyong-ju and Seoul. The structured questionnaire included items about the frequency of eating out, the choice of eating-out menus, the decision maker of the eating-out process, the attitudes toward eating out and the general characteristics of the families. The major results are as follow: 1) In the cafe of telephone delivery service, and eat-in restaurants, the subjects showed statistical significance (p < 0.01). With respect to telephone delivery service, families in Step II used it most frequently, but families in Step I rarely used it. With respect to eat-in restaurants, families in Step II used them most frequently but families in Step IV rarely used them. 2) In all the family life cycle steps, the most favorable menu was fried chicken for take-out type, Chajang noodles, fried chicken and pizza fur telephone delivery, pizza for internet delivery, raw fish and beef for eat-in restaurant, Docbokki, laver rolled rice and ramyun for convenience flood stores. 3) The wife was most influential in making decisions about the take-out type (p < 0.001). In the case of telephone deliveries (p < 0.001), the wife was the most influential in the families of Steps I and II, but the children were the most influential in the families of Steps III and IV. In the case of eat-in restaurants (p < 0.001), the husband had the most effect on the decision-making process. In the case of convenience flood stores (p < 0.001), the children were the most influential in the families in Steps III and IV. In most family life cycle steps, each of them chose their own meal. 4) from a factor analysis perspective, attitudes toward eating out have been grouped according to two factors, namely 'Advantage' and 'Nutrition'. No factor showed a significant difference among the family life cycle steps.