• 설비공학논문집
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• 제18권8호
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• pp.641-648
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• 2006

In this study, a two-stage phase-separate cycle was investigated analytically to improve the performance of the $CO_2$ system in the cooling mode. The simulation results were verified with the measured data. The predictions using the simulation model were consistent with the measured data within ${\pm}20%$ deviations. The performance of the modified $CO_2$ system with the two-stage phase-separated cycle was analyzed with the variations of outdoor temperature and EEV opening. The cooling COP decreased with the increase of compressor frequency. The highest COP was 2.7 at compressor frequencies of 30 Hz and 30 Hz for the first and second compressors, respectively. In addition, the cooling COP increased by 9.3% with an application of optimum control of the first and second-stage EEV openings.

• 대한간호학회지
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• 제27권1호
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• pp.71-82
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• 1997

In this paper, the study model, which presents the patterns of how the changing mechanisms are adopted to the changing stages of smoking cessation, was developed by modifying the integrative model of Prochaska et al. (1983) with including seven changing mechanisms which were identified by Oh and Kim(1996). Then the developed study model was exploratively tested with 155 University student between 20 and 29 years of age as subjects. According to the study results. among the five mechanisms. which are significant in explaining the differences between stages. DUNCAN post-comparison showed that the least applied ones were Stimulus Control, Self Determinism, Cognitive Restructuring in the precomplation stage, and Reinforcement and Dramatic Relief. in the relapsed stage. In the comtemplation stage. it was observed that Dramatic Relief is used most frequently and that the other two mechanisms, Information Management and Cognitive Restructuring, showed different results from those inferred in the study hypothesis. In the case of Information Management, it was excluded from the analysis it was not included in explaining significant difference among changing stages, but Cognitive Reconstruction turns out to be a more frequently used mechanism in the action stage rather than in the comtemplation stage. Helping Relationship was also excluded in the post-comparison analysis since it was not included in explaining significant difference among changing stages and Reinforcement was a more frequently used mechanisms in the comtemplation stage. Stimulus Control turns out to be the connecting mechanism which was most frequently used in both the contemplation and action stages. Self Determination was most frequently used in the action stage rather than in both the comtemplation stage and action stage, differing from the presumption of the model. Lastly, subjects in the relapsed stage were utilizing Stimulus Control and Self Determination at the same level as subjects in the precontemplation stage. and the utilization of both Reinformcement and Dramatic Relief was lower than that of the precomtemplation stage, that is, at the lowest level. Only Cognitive Restructuring was used of the same level as the comtemplation stage. The relapsed stage in this study did not represent the preparation for action stage as presumed in the model of Prochaska et. al. (1983) but did show a pattern similar to the initial stage of smoking cessation. However, since this interpretation about the relapser was based on only a small number of relapsers(n=5), this conclusion may not be reliable.

• 한국항공우주학회지
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• 제39권4호
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• pp.314-320
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• 2011

본 연구에서는 2단으로 구성된 달착륙선 충격 흡수 장치에 대한 최적화를 수행하였다. 충격 흡수 장치의 복잡한 충격거동을 모사하기 위해 1차원 구성방정식 모델을 제안하였으며, 이와 함께 상용해석 소프트웨어인 ABAQUS를 활용하여 최적화를 위한 2차 다항회귀 메타모델을 구성하였다. 구성된 메타모델을 순차적 근사 최적설계 기법에 적용하여 2단 충격 흡수 장치의 최적화를 수행하였으며, 이를 통해 허니컴 구조를 이용한 충격 흡수장치의 셀크기와 포일 두께를 변화시킴에 따라 달착륙선의 월면 착륙 시 충격하중을 크게 저감시킬 수 있음을 확인하였다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2001년도 추계학술대회 논문집
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• pp.395-398
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• 2001

Studies on quantity discounts have been in two directions since Buchanen[1] published that suppliers provide quantity discounts for price discrimination and for channel efficiency. The quantity discounts for price discrimination have been treated in economics. On the contrary, the quantity discounts for channel efficiency have been studied in production management with assumptions and focuses different from economics. In this paper, the differences in each area are analyzed and purchasing situations that supplier's motivation on quantity discounts occurs is analyzed and the purchasing situations for two-stage quantity discounts are specified. In conclusion, we suggest that suppliers can enhance channel coordination through two stage quantity discounts in these purchasing situations.

• 한국정밀공학회지
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• 제16권2호통권95호
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• pp.164-175
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• 1999

If the camera plane is nearly parallel to the calibration board on which objects are defined, most of existing calibration approaches such as Tsai's radial-alignment-constraint method cannot be applied. Recently, for such an ill-conditioned case, Zhuang & Wu suggested the linear two-stage calibration algorithm assuming that the exact values of focal length and scale factor are known a priori. In this paper, we developed an iterative two-stage algorithm starts with initial guess fo the two parameters to determine the value of the others using Zhuang & Wu's method. In the second stage, the two parameters are locally optimized. This process is repeated until any improvement cannot be expected any more. The performance comparison between Zhuang & Wu's method and our algorithm shows the superiority of ours. Also included are the computational results for the effects of the distribution and the number of calibration points on the calibration performance.

• 한국추진공학회지
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• 제16권1호
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• pp.16-24
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• 2012

비행 마하수 6으로 운용되며, 지상 정지 추력으로부터 사용이 가능하도록 2단 추진체 개념이 적용된 스크램제트 엔진 비행체에 대한 개념설계를 수행하였다. 1단은 고체로켓을 적용하였으며, 2단은 탄화수소 계열의 연료를 사용하는 스크램제트 엔진을 적용하였다. 개념설계를 위하여 2,000 km의 운용거리와 0.2 톤의 탑재체 무게를 가정하였다. 개념설계의 첫 번째 단계로 3-DOF 코드를 이용하여 비행궤도를 계산하였으며, 계산된 비행궤도를 바탕으로 일차원-비평형 유동 코드와 NASA의 HASA 데이터베이스를 이용하여 스크램제트 엔진에 대한 개념설계를 수행하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.309-317
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• 2011

비행 마하수 6으로 운용되며, 지상 정지 추력으로부터 사용이 가능하도록 2단 추진체 개념이 적용된 스크램제트 엔진 비행체에 대한 개념설계를 수행하였다. 1단은 로켓을 적용되었으며, 2단은 탄화수소 계열의 연료를 사용하는 스크램제트 엔진이 적용되었다. 개념설계를 위하여 반경 2,000km의 운용거리와 0.2톤의 탑재체 무게를 가정하였다. 개념설계의 첫 번째 단계로 3-DOF 코드를 이용하여 비행궤도를 계산하였으며, 계산된 비행계도를 바탕으로 일차원-비평형 유동 코드와 NASA의 HASA 데이터베이스를 이용하여 스크램제트 엔진에 대한 개념설계를 수행하였다.

• 가정과삶의질연구
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• 제8권1호
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• pp.83-100
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• 1990

The purposes of the study are to understand of rural family life cycle(FLC) and to get a FLC model for the twentieth in rural area. Data for the study were collected from 603 farm households in rural area. The major findings are as follows; 1) The age of first marriage was 21.5 years old(urban : 22.4), the first bearing 23.2(24.2), the last bearing 31.7(32.6), the first child marriage 47.2(46.5), and the last child marriage 59.7(52.7). The number of child and interval were 3.9 persons and 2.9 years respectively. From the survey results, the rural family life cycle was established. Establishment stage(from the marriage to the 1st child birth) : 21-23 yrs. Extension stage(from the 1st child birth to the last child birth) : 23-32 yrs. Complete extension stage(from the last child birth to the 1st child's marriage) : 32-47 yrs. Shrinking stage(from the 1st child's marriage to the last child's marriage) : 47-60 yrs. Complete shrinking stage(from the last child's marri ge to the death of husband) : 60-63 yrs. Dissolution stage(from the death of husband to the death of wife) : 53-75 yrs. 2) In general, the older the age, the younger the first marriage age, the greater the number of child, and the longer the interval of child bearing. The last child's marriage was too last to have the period of recovery stage. In terms of FLC by marital chorts, the later the year of marriage, the older the age of the first marriage and first baby bearing, the smaller the number of child, and the faster the launching stage. The higher the educational level, the older age of the first marriage and the first baby bering, the smaller the number of child, and the shorter the interval of child bearing. 3) Two types of rural FLC model for the twentieth were formulated. Type A was formulated based on the survey results and type B was formulated based on 『'88 population dynamics survey』 of Economic Planning Board(EPB). 「TYPE A」*Establishment stage(from the marriag to the 1st child birth) : 22.5-23.5 yrs. one child : the 1st child's marriage(49.5yrs), the death of husband(64.2yrs), the death of wife(71.7yrs) two children : the last child's birth(25.7yrs), the last child's marriage(51.7 yrs) three children : the last child's birth(27.9yrs) the last child's marriage(53.9yrs) 「TYPE B」*Establishment stage(from the marriage to the 1st child birth) : 25.3-26.3 yrs. one child : the lst child's marriage(52.3yrs), the death of husband(67.0yrs), the death of wife(74.5yrs) two children : the last child's birth(27.8yrs), the last child's marriage(53.8 yrs.) three children : the last child's birth(29.3yrs), the last child's marriage(55.3yrs).

• The Korean Journal of Ceramics
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• 제5권3호
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• pp.296-302
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• 1999

The state of the art of the 2-stage swirl calciner is to make 2-stage counter gas flow in a calciner with cooler hot air. Gas flow in the calciner increases retention time of raw mix particles. Simple structure of the 2-stage swirl calciner operated optimally the rotary cement kiln. In this study, in order to decide the entrance type of the cooler air of the optimal calciner model, an entrance cooler air velocity, the input points of raw mix were analyzed in many aspects with cold model experiment and computational fluidized dynamic simulation. It was found that the entrance type of cooler air fully splite 2-stage for the optimal condition of the cold model calciner. The operation conditions were that the input feeding, the cooler air velocity and the air velocity of throat were 0.33kg/$\textrm m$3$, 15m/s and 20m/s respectively. The performance of 150 t/d the pilot plant connected with the kiln rising duct was that volume capacity of the calciner is over 430 kg/$\textrm m$3$-h, decarbonation rate of raw mix apparently 90%, heat consumption 950 kcal/kg-cli and retention time of raw mix 2.4 sec. Its the best operating condition is cooler air velocity 18m/s, the gas velocity of throat 25m/s, feeding rate of raw mix 10t/h. The operating experience of the pilot plant confirmed the success of scale up for over 3000 t-cli/d.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.66.2-66
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• 2002

In this study, a novel systematic design procedure by Genetic Algorithm of a two stage relief valve is proposed. First of all, a mathematical model describing the dynamics of a balanced piston type relief valve has been derived. Governing equations such as dynamic equations for the main spool and the pilot spool and flow equations for each orifice are established. The mathematical model is verified by comparing the results of simulation with that of experiments. Furthermore, influences of the parameters on the dynamic characteristics of a relief valve have been investigated by simulation of the proposed model. Major design parameters on the valve response are determin...