2단계 분배체계를 위한 확률적(Q, r)재고모형

심재홍,최규탁,김정자 한국경영과학회 1998 韓國經營科學會誌 Vol.23 No.1

다단계 재고시스템이 현실적으로 많이 사용되고 있으나 이들 시스템의 수리적 모형이 매우 복잡하여 최적 운영 재고정책들을 얻기가 어렵기 때문에 다단계 재고 시스템의 운영에 관한 지침은 그다지 많지 않다. 더우기 부분부재고를 고려한 재고모형이 좀더 현실적이지만 이것을 고려한 다단계 재고 시스템을 위한 운영정책은 거의 제시되지 않고 있다. 본 연구에서는 중앙창고와 각 소매점들이 연속조사정책(Q,r)모형을 하는 2단계 분배시스템에서 수요가 확률적이고 부분부재고를 고려한 상황하에서 중앙창고와 각 소매점간의 상호작용을 기초로 하여 시스템의 연간 총변동비를 최소화 하는 최적 또는 근사적 재고정책을 발견하는 반복적인 절차를 제시하였다. 이 절차는 비록 수학적인 복잡성 때문에 수렴이 정확히 증명될 수 없었지만, 많은 수치실험을 한 결과 해외 수렴이 빠르게 진행되어 본 연구의 모형이 타당하다는 것을 확인할 수 있었다. 따라서 본 연구에서 제시된 모형이 다단계 분배 시스템의 실제적인 문제 해결에 유용할 것으로 생각된다. This paper develops a two-echelon inventory model with time-weighted partial backorders. The presented model assumed to follow continuous review (Q.r) policy for both the retailers and the central warehouse under stochastic demand. A heuristic method to find an optimum-tending solution for total varible system cost per year incurred at the central warehouse and retailers in a system is suggested. To show the usefulness of the above model, numerical examples are illustrated for verification and validation purpose.

청소년의 근로 여부에 따른 신체활동 및 스트레스 비교

강지은,김혜원,백다인,신지원,신혜진,심지선,윤도연,이규리,이보라,이혜민,최주연 이화여자대학교 간호과학대학 2014 이화간호학회지 Vol.- No.48

Purpose: The purpose of this study was to investigate the stress and the physical activity according to working in Korean adolescents. Methods: Data were collected from 3 high schools in Seoul and Gyeonggi-do. The total number of four hundred twenty subjects were participated and they completed general questionnaire, International Physical Activity Questionnaire (Korean version) and adolescents stress scale. Data were analyzed by descriptive statistics and t-test using SPSS 21.0 program. Results: The number of employed was 151 (45.2%) and the number of unemployed was 183 (54.8%). Reasons for working were to earn money (44.0%) and to purchase significant product (35.6%). Moderate physical activities of employed students were more than them of unemployed students and there was significant difference (t=3.261, p˂.001). There was no significant difference between employed and unemployed students in the total score of stress. However, there were significant differences on school stress (t=2.854, p=.005) and economical stress (t=3.959, p˂.001) in the subcategory. The stress of employed was higher than the stress of unemployed. Conclusion: As shown in the above result, employed adolescents reported higher levels of both physical activity and stress than unemployed adolescents, thus indicating that employment status of adolescents has a significant impact on physical and mental health. Nursing implications include developing quality care for employed adolescents based on the community health nursing, and providing health education at schools in terms of adolescent employment.

GFRP 인장시험 시 적외선 열화상 계측

김진우,이동기,심재기,김재열,최승현 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

Property of GFRP is naturally dependent on the property of matrix, but receives of temperature effects by external force. Therefore, determination of mechanical property by effect of temperature in GFRP is most crucial factor. In this paper, temperature distribution during crack propagation from temperature change under tensile test was proposed through IR thermography camera. Lock-in thermography method, which is one of technique in IR thermography camera to measure minute change in temperature, was utilized to monitor temperature distribution and change during crack propagation. Method to analyze temperature distribution during crack propagation under tensile test of GFRP via IR thermography camera was suggested. Anisotropy in fiber orientation showed longer fracture time and lower maximum temperature.

용접결함의 형상인식을 위한 신경회로망 알고리즘의 성능 비교

김재열,심재기,이동기,김창현,송경석,양동조 한국공작기계학회 2003 한국공작기계학회 추계학술대회논문집 Vol.2003 No.-

In this study, we compared backpropagation neural network(BPNN) with probabilistic neural network(PNN) as shape recognition algorithm of welding flaws. For this purpose, variables are applied the same to two algorithm. Here, feature variable is composed of time domain signal itself and frequency domain signal itself. Through this process, we comfirmed advantages/disadvantages of two algorithms and identified application methods of two algorithms.

Cyclic behaviour of end-plate beam-to-column composite joints

Rui Simões,Luís Simões da Silva,Paulo J.S. Cruz 국제구조공학회 2001 Steel and Composite Structures, An International J Vol.1 No.3

An experimental research program on end-plate beam-to-column composite joints under cyclic loading is presented. The major focus relates to the identification of the contribution of the concrete confinement in composite columns to the behaviour of the joint, on internal nodes and external nodes, together with an assessment of degradation of strength and stiffness in successive loading cycles. From the experimental results it was possible to identify the various failure modes and to fit the corresponding hysteretic curves to the Richard-Abbott and Mazzolani models. These curve-fitting exercises highlighted the need to adapt both models, either for improved ease of application, or to deal with some aspects previously not covered by those models.

섬유강화 복합재료 사출성형품의 섬유배향상태

이정주,김진우,김혁,한길영,심재기,이동기 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-

Injection molding is the most widely used process for the industrial forming of plastic articles. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation·orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of welding parts in injection-molded products is assessed. And the effects of fiber content and injection mold shapes on the fiber orientation in case of fiber reinforced polymeric composites are studied experimentally.

선진복합재료 적층판의 동적 층간 파괴 인성평가

김지훈,양인영,김영남,심재기 한국산업안전학회 1998 한국안전학회지 Vol.13 No.4

In this paper, an investigation was performed on the dynamic interlaminar fracture toughness of CFRP(carbon fiber reinforcement plastics) composite laminates. Composite laminates used in this experimentation are CF/EPOXY and CF/PEEK laminated plates. In the experiments, Split Hopkinson's Bar(SHPE) test was applied to dynamic and notched flexure test. The mode II fracture toughness of each unidirectional CFRP was estimated by the analyzed deflection of the specimen and J-integral with the measured impulsive load and reactions at the supported points. As an experimental result, the vibration amplitude of CF/PEEK laminates appear more than that of CF/EPOXY laminates for the J-integral and displacement velocity at a measuring point. Also, it is thought that the dynamic. fracture toughness of two kind specimens(CFRP/EPOXY and CF/PEEK) with the in crease of displacement velocity becomes a little greater at a measuring point within the range of measurement.

대학생의 스마트폰 중독 정도, 안구건조증, 경부 통증 및 수면의 질에 관한 연구

고은재,김나연,김도연,김은혜,김지연,박영신,심현수,윤지현,이소미,이해수,박효정 이화여자대학교간호학회 2020 이화간호학회지 Vol.- No.54

Purpose: The purpose of this study was to identify correlation among the degree of smartphone addiction, dry eye syndromes, neck pain and sleep quality. Method: A total of 172 students were recruited for the data collection. Data were analyzed using frequency, percentage, average, standard deviation, t-test, ANOVA, Scheffe test and Pearson's correlation using the SPSS program. Results: The degree of smartphone addiction, dry eye syndromes, neck pain and sleep quality showed positive correlation. As the level of smartphone addiction is higher, dry eye syndromes, neck pain and sleep quality become worsen. Conclusion: Based on the results of this study, it shows that the quality of sleep had a significant correlation with smartphone addiction. Therefore, it is necessary to consider the nursing intervention to increase the quality of sleep, neck pain and dry eye syndromes in further study.

CH₄ mixing ratios at microbar pressure levels of Jupiter as constrained by 3-micron ISO data

Kim, S.J.,Sim, C.K.,Sohn, M.R.,Moses, J.I. Academic Press 2014 Icarus Vol.237 No.-

Infrared Space Observatory (ISO) data of Jupiter are revisited in order to derive CH<SUB>4</SUB> mixing ratios at microbar pressures in the atmosphere. We utilize the most updated radiative transfer programs to construct a 3-μm emission model of CH<SUB>4</SUB> to be compared with the ISO data. From the model-data comparisons, we derive the high-altitude CH<SUB>4</SUB> mixing ratios, which turn out to be at least 10 times smaller than the microbar CH<SUB>4</SUB> mixing ratios assumed in the Galileo probe analysis (Seiff, A. et al., 1998. Thermal structure of Jupiter's atmosphere near the edge of a 5-μm hot spot in the north equatorial belt. J. Geophys. Res., 103, 22857-22889. doi:10.1029/98JE01766), but which are approximately consistent with ultraviolet airglow observations and with available photochemical models that assume relatively weak atmospheric mixing. We also compare the derived CH<SUB>4</SUB> profile with results from other investigations reported in literature and discuss the implications with respect to photochemistry and vertical transport in the stratosphere of Jupiter.

경추부 후종인대의 석회침착 1예 보고 : Case report

이현재,김종현,고학종,채진,최길수,심보성 중앙대부설한국의과학연구소 1975 한국의과학 Vol.7 No.4