• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.3
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• pp.114-121
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• 2007

In this study, a modified reverse flow type, one of the triple effect absorption cycles, is studied for performance improvement. The cycle simulation is carried out by using EES(Engineering Equation Solver) program for the working fluid of $H_2O/LiBr$ solution. The split-ratios of solution flow rate, UA of each component, pumping mass flow rate of solution are considered as key parameters. The results show that the optimal SRH (split ratio of high side) and SRL (split ratio of low side) values are 0.596 and 0.521, respectively. Under these conditions, the COP is maximized to 2.1. The optimal pumping mass flow rate is selected as 3 kg/s and the corresponding UAEV A is 121 kW/K in the present system. The present simulation results are compared to the other literature results from Kaita's (2002) and Cho's (1998) triple effect absorption systems. The present system has a lower solution temperature and a higher COP than the Kaita's modified reverse flow, and it also gives a higher COP than the Cho's parallel flow by adjusting split ratios.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.2
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• pp.94-100
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• 2005

This paper presents the application of integrated mathematical programming approach for the design of cellular manufacturing. The proposed approach is carried out in two phases The first phase concerning exceptional elements(EEs) in cell formation and the second phase facilities layout design. This paper considers the total costs of three important costs for (1) intercellular transfer (2) machine duplication and (3) subcontracting. One of Important issue is the calculation of the number of machines considering the maximum utilization of machines and the available capacity of a machines that can be transferred between cells. Facilities layout design is considered to reflect the real field data taking in to account the operational sequence of the parts to be manufactured. The model is formulated as mixed integer programming that is employed to find the optimal solution.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.6
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• pp.537-544
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• 2008

In this paper, flow characteristics of an adiabatic capillary tube in a transcritical $CO_2$ have been investigated employing the homogeneous model. The model is based on fundamental equations of mass, energy and momentum which are solved simultaneously. Two friction factors(Churchill) and viscosity(McAdams) are comparatively used to investigate the flow characteristics. Supercritical and subcritical thermodynamic and transport properties of $CO_2$ are calculated employing EES property code. Flow characteristics analysis of $CO_2$ adiabatic capillary tube is presented to offer the basic design data for the operating parameters. The operating parameters considered in this study include inlet temperature and pressure of an adiabatic capillary tube, evaporating temperature and inner diameter tube. The main results were summarized as follows : inlet temperature and pressure of an adiabatic capillary tube, evaporating temperature, mass flowrate and inner diameter of $CO_2$ adiabatic capillary tube have an effect on length of an adiabatic capillary tube.

• Korean Journal of Pharmacognosy
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• v.4 no.1
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• pp.23-27
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• 1973

Korean ergot sclerotia which were collected from Agropyron semicostatum $N_{EES}$, Miscanthus sinensis $A_NDERS$ var. purpurascens $R_{END}$, M. sacchariflorus $B_{ENTH}$. et HOOK,. M. sinensis $A_{NDERS}$., Eulalia speciosa $O.{\;}K_{UNTZ}$, Themeda triandra $F_{ORSK}$. var. japonica $M_{AKINO}$, and Phalaris arundinacea L. were investigated for their alkaloid constituents. Quantitative determinations of alkaloids were carried out using a modified procedure of van $U_{RK}$ and $M_{ICHELON}-K_{ELLEHER}$ methods. The results showed that the two ergots from Agropyron semicostatum and Phalaris arundinacea contained total alkaloids up to 0.137 per cent. The alkaloids of these two ergots are mostly water-insoluble alkaloids. The ergots parasitizing Reed Canary grass was found to contain both water-soluble and water-insoluble alkaloids. The TLC and PPC tests for the ergot alkaloids from Agropyron semicostatum and Phalaris arundinacea revealed that they contain at least two alkaloids, respectively, and that the ergot from Themeda triandra $F_{ORSK}$. var. japonica has one. The lipid contents of the seven ergots ranged from 13 to 29 per cent.

• The Korean Journal of Financial Studies
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• v.11 no.1
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• pp.177-198
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• 2005

본 연구는 기업의 자본비용을 반영한 초과이익(excessive earnings)의 우리나라 주식시장에서 투자지표로서의 유용성에 대해서 분석하였다. 이를 위해서 주당초과이익과 함께 전통적인 성과지표인 주당순이익을 비교분석하였으며, 주된 분석결과를 요약하면 다음과 같다. 첫째, 분석기간 중 주당순이익을 기준으로 보면 대부분의 기업들이 양(+)의 값을 가지는 것으로 나타났으나, 주당초과이익의 경우에는 대다수의 기업들에서 음(-)의 값을 가지는 것으로 나타났다. 이는 기업들이 주주들에게 충분한 보상을 하지 못하고 있다는 것을 의미한다. 둘째, 주당초과이익(EES)은 전통적인 성과지표(EPS, ROE)보다 주식수익률과 상관관계가 높으며, 주당순이익에 비하여 주당초과이익을 기준으로 포트폴리오를 구성하는 경우에 보다 높은 초과수익률을 올릴 수 있는 것으로 나타났다. 셋째, 주당순이익 기준에 의한 하위집단의 누적평균초과수익률은 유의적으로 음의 값을 보이는 반면에 상위집단은 0과 차이를 보이지 않는다. 그러나 주당초과이익 상위집단의 수익률은 시장수익률보다 유의하게 높고 하위집단에서는 낮게 나타난다. 이는 주당순이익이 낮은 EPS 하위집단의 경우는 당기순손실이 주는 부정적 효과가 반영된 것으로 유추할 수 있으며, 투자지표로서는 EES가 유용한 것으로 판단된다. 결론적으로 기업의 진정한 부가가치 생산은 자본비용을 반영한 순이익이며, 제한적이지만 우리나라 주식시장에서 초과이익이 투자지표로서 활용될 수 있을 것으로 판단된다.

• Environmental Analysis Health and Toxicology
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• v.20 no.3 s.50
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• pp.243-248
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• 2005

Mancozeb (MCZ), a polymeric complex of zinr and manganese salts of ethylene bisthiocarbamate, is widely used in agriculture as fungicidel, insecticides, and herbicides. MCZ can be occupationally and environmentally exposed to human and has been reported to have detrimental effects on the reproductive system, but the toxicity of MCZ on immune responses has not been systematically investigated. We investigated the effects of MCZ exposure on the activities of murine splenocytes through evaluation of splenocytes cellularity and INF-$\gamma$ synthesis. Splenocytes were examned ex vivo from mice orally treated with various doEes of MCZ for 1 day (acute exposure, 2,100, 5,000, 10,000 mg/kg) or ior 5 consecutive days per week for 4 weeks (subacute exposure,250, 1,000, 1,500 mg/kg/day) fellowed by culture for 2 days in the presence of Con A or PHA plus IL-2. Splenocytes Iron naive mice were cultured with various concentration of MCZ (50, 500, 1,000 ng/ml) in the presence of Con A or PHA plus IL-2 for 2 days in vitro. IFN-$\gamma$ production was decreased with the in vitro exposure to all concentration of MCZ. The spleen cellularity and IFN -$\gamma$ production by splenocytes from MCZ -acutely and - subacutely exposured mice were decreased in comparision with that oi control group.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.119-125
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• 2011

The analysis of performance characteristics in a refrigerator truck using R404A and R744 was carried out by using theoretical method, and each performance was compared with a variation of operating conditions. The components and cycle simulation model were developed by using EES program. To investigate the performance characteristics with operating conditions, the performance of both systems was simulated according to indoor temperature, outdoor temperature, outdoor air velocity and compressor speed. As a result, the R744 system had a better COP than R404A system for given operating condition. The cooling capacity was not increased over the outdoor air velocity of 3 m/s. Besides, the performance of R404A system was more sensitive to operating conditions compared to that of R744 system.

• Progress in Superconductivity and Cryogenics
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• v.16 no.4
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• pp.57-61
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• 2014

Output fluctuation which is generated in wind power farm can hinder stability of total power system. The electric energy storage (EES) reduces unstable output, and superconducting magnetic energy storage (SMES) of various EESs has the proper performance for output compensation of wind power farm since it charges and discharges large scale power quickly with high efficiency. However, because of the change of current within SMES, the electromagnetic losses occur in the process of output compensation. In this paper, the thermal effect of the losses that occur in SMES system while compensating in wind power farm is analyzed. The output analysis of wind power farm is processed by numerical analysis, and the losses of SMES system is analyzed by 3D finite element analysis (FEA) simulation tool.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.10
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• pp.687-696
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• 2010

In this study, FDD algorithm was developed using the normalized distance method and general pattern classifier method that can be applied to constant air volume air handling unit(CAV AHU) system. The simulation model using TRNSYS and EES was developed in order to obtain characteristic data of CAV AHU system under the normal and the faulty operation. Sensitivity analysis of fault detection was carried out with respect to fault progress. When differential pressure of mixed air filter increased by more than about 105 pascal, FDD algorithm was able to detect the fault. The return air temperature is very important measurement parameter controlling cooling capacity. Therefore, it is important to detect measurement error of the return air temperature. Measurement error of the return air temperature sensor can be detected at below $1.2^{\circ}C$ by FDD algorithm. FDD algorithm developed in this study was found to indicate each failure modes accurately.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.294-298
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• 2008

The major threats that human being is facing nowadays are the Climate change, depletion of the fossil fuels at a rapid rate and energy costs. A significant portion of world energy consumption is consumed by domestic heating and cooling. And heat pumps, due to their higher utilization efficiencies as compared to conventional heating and cooling systems, offer an attractive solution to this problem. Among the types of heat pumps, the Geothermal heat pump or Ground-source heat pump is a highly efficient, renewable energy technology for space heating and cooling. The Ground-source heat pump uses the Earth as a heat sink in the summer and a heat source in the winter. And the Earth, having a relatively constant temperature, warmer than the air in winter and cooler than the air in summer, offers an excellent heat source in winter and heat sink in summer.. This paper will discuss an overview of the types of heat pumps, its operation, benefits of using geothermal heat pumps, soil characteristics, and overview of some experimental works. Finally it will briefly discuss the opportunity of using these energy efficient systems (EES) in the HVAC market of South Korea.