• Journal of Korean Institute of Industrial Engineers
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• v.39 no.5
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• pp.440-449
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• 2013

We consider a reverse supply chain with a production facility and a recovery facility, and address the joint control of production and disposal decisions for sustainable operations. Demands are satisfied from on-hand inventory of serviceable products, replenished via manufacturing or remanufacturing. Sold products may be returned after usage and each returned product is disposed of or accepted for recovery. Accepted returned products are converted into serviceable products after remanufacturing process. Formulating the model as a Markov decision process, we characterized the structure of the optimal production and disposal policy as two monotone switching curves under a special condition. Three types of heuristic policies are presented and their performance is numerically compared.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.1
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• pp.22-30
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• 1999

This experiment was carried out to determine the forage yield and mineral contents of silage corn(Zea mays L.), and N balance, soil chemical characteristics and nitrate-N level in infiltration water by different types and N rates of liquid manure applied. Seven treatments consisting of chemical fertilizer $200kg\;N;ha^{-1}$, liquid cattle manure 200, 320 and $440kg\;N;ha^{-1}$, liquid swine manure 200, 320 and $440kg\;N;ha^{-1}$ were arranged in a randomized complete block design with three replications. The results obtained at National Livestock Research Institute, RDA, in Suweon from May 1997 to Aug. 1997 are summarized as follows : There were no significant differences in percentage of dry matter among the treatments, but significant dry matter yield differences were found (P<0.05), and also the mean dry matter yield of liquid swine manure plot was higher than that of liquid cattle manure plot. Potassium, calcium and magnesium contents of silage corn increased with increasing liquid manure application rates (P<0.05). Nitrate-N content of silage corn in the liquid cattle manure treatments was not influenced by liquid manure application rates, but that in the liquid swine manure treatments increased with increasing the N rates of liquid manure application. pH and contents of exchangeable canons of the soil after experiment were raised by increasing the amount of liquid manure application. Available $P_2O_5$ content in topsoil(0-10cm) was highest as $340mg\;kg^{-1}$ at the plot of liquid swine manure $440kg\;N;ha^{-1}$. Concentration of nitrate-N in infiltration water increased at the plot of liquid swine manure $440kg\;N;ha^{-1}$. Amount of nitrogen balance increased with increasing liquid manure application rates. Based on the results of this experiment, it is suggested that the mean dry matter yield of liquid swine manure plot was higher than that of liquid cattle manure plot, and the amount of nitrogen balance increased with increasing liquid manure application.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.4 s.148
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• pp.440-450
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• 2006

In this paper, we suggest a design concept of defining the propeller geometry by stacking up the blade sections aligned with propeller surface streamlines. Numerical and experimental propeller open water(P.O.W.) characteristics of a newly designed propeller are presented. The surface streamlines for a propeller are obtained by using the panel method. Redefinition of the blade sections aligned with the streamlines is provided together with 8-spline modeling, by which we manufacture model propellers. We carried out the P.O.W, tests in a towing tank in order to show the effect of the present method on P.O.W. characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.4
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• pp.440-451
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• 1998

An experimental study has been conducted to investigate solidification of NH$_{4}$CI-H$_{2}$0 mixtures inside a vertical rectangular enclosure. Solidification process is visualized by the shadowgraph method. Emphasis is placed on the effect of solidification parameters such as the aspect ratio, cooling wall temperature and initial composition. The aspect ratio shows a dominant effect on the number and developing time of the double diffusive layers which reveals the relative strength of solutal convection to thermal convection. Similar flow pattern is observed when the concentration difference between interdendritic liquid and the pure liquid which drives solutal convection is the same regardless of the different cooling wall temperature and initial concentration.

• Transactions of Materials Processing
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• v.16 no.1 s.91
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• pp.61-66
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• 2007

Powder injection molding(PIM) is widely used for many parts in the field of automotives, electronics and medical industries, due to the capability of net shaping for complex 3-D geometry. Powder injection mold design for the dental scaler tip, a component of medical appliance, was presented. In comparison with conventional machining process, powder injection molding has many advantages, specially in price and dimensional stability, for molding dental scaler tip which has complex geometry. Both product design and mold design for dental scaler tip were presented. A PIM feedstock was made of stainless series(17-4PH, 316L, 440C) powder and a wax based binder. The 'rapid mold' concept was applied to manufacture the various forms and materials of dental scaler tip including vibration characteristics.

• Journal of International Academy of Physical Therapy Research
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• v.3 no.2
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• pp.440-445
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• 2012

The purpose of this study was to assess the effects of lower extremity resistance training using elastic bands on balance in elderly people. Eight elderly persons each were randomly assigned to a test group(resistance exercise group, REG) or a control group(CG). FRT and TUG test were used to compare balance before and after exercise. Exercise programs were implemented three times a week for 40 minutes for nine weeks. They did warm-up exercise for 5 minutes and then lower extremity resistance exercise using elastic bands for 30 minutes. And then they did cool-down exercise for 5 minutes. TUG and FRT significantly decreased but in the control group it did not significantly decrease. In comparison between the groups, TUG and FRT significantly reduced in the resistance exercise group compared to the control group. Lower extremity resistance training using elastic bands performed by elderly persons are considered to be effective in improving balance.

• Current Optics and Photonics
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• v.1 no.5
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• pp.440-455
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• 2017

In this paper, we carry out a performance analysis of a two-user free-space optical (FSO) communication system with photodetector multiplexing, in which the two users are defined as the primary user (PU) and secondary user (SU). Unlike common single-user FSO systems, our photodetector multiplexing FSO system deploys a shared detector at the receiver and enables PU and SU to send their own data synchronously. We conduct the performance analysis of this FSO system for two cases: (1) in the absence of background radiation, and (2) in the presence of background radiation. Decision strategies for PU and SU are presented according to the two scenarios above. Exact and approximate conditional symbol-error probability (SEP) expressions for both PU and SU are derived, in an ideal channel with no fading. Average SEP expressions are also presented in the no-background-radiation scenario. Additionally, in some particular cases where the power ratio tends to 0.5 or 1, approximate SEP expressions are also obtained. Finally, numerical simulations are presented under different conditions, to support the performance analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.6
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• pp.440-445
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• 2018

This study proposes a novel control and design method for a grid-connected inverter with an LCL filter without damping. The current resonance phenomenon must be considered when designing the grid-connected inverter system with an LCL filter. Passive or active damping is used in the inverter system to reduce the resonant current. However, passive damping reduces the efficiency of the system, and active damping methods are complex. If the resonant frequency is in a specific region, then the system will be unstable. This study examines the process of stabilizing the entire region without resonant damping. The validity of the proposed method is verified through simulation and experimentation.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.440-441
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• 2023

가치주와 성장주의 정의는 모호하다. 그렇기에 사회에 다양한 혼란이 빚어지고 있다. 본 연구에서는 그 모호성으로 인해 생기는 혼란을 줄이고자 새로운 주식 종목 분류 모형을 제안한다. 유명 성장 지수와 가치 지수 내 종목을 통해 지도 학습이 가능한 환경에서, 종목들의 주가 등에서 새로운 지표를 만들어낸 후, 그 지표를 LSTM 모델을 통한 기계학습으로 학습하는데 활용한다. 보이지 않는 패턴을 학습한 모델을 검증기에 부착해 모호한 주식을 분류하는데 응용할 수 있다.

• Advances in concrete construction
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• v.2 no.1
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• pp.1-11
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• 2014

This paper demonstrates an experimental study to evaluate the effects of environmental exposures on the bond between ribbed Glass Fiber Reinforced Polymer (GFRP) reinforcing bars and concrete. The equation recommended by ACI 440-1R-06, for the bond stress,was evaluated in this study. A total of 16 pullout samples, 12with GFRP bars and 4with steel bars, were exposed to two different harsh environments for different periods of time. The exposed harsh environments included direct sun exposure and cyclic splash zone sea water. The variation in the shear (bond) strengths before and after exposure was considered as a measure of the durability of the bond between GFRP bars and concrete.Experimental results showed there is no significant difference of the bond strength between 60 and 90 days of exposures.It also showed that the empirical equation of the bond stress calculated by ACI 440-IR-06 is very conservative.