• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.69-75
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• 2019

The cooling performance of heat pump system for light-duty commercial electric vehicle was evaluated experimentally. The cooling performance characteristics of the heat pump for light-duty commercial electric vehicles were evaluated by varying the temperature, flow rate of chiller coolant, and electric compressor speed, under the exterior air temperature of 35 ℃ and interior air temperature of 25 ℃. Increasing the compressor speeds decreased the cooling system efficiency by 16.4 % on average with the cooling capacity increasing by 8.0 % on average and the compressor work increasing by 27% on average. To use waste heat from the coolant to chill power electronic components, such as the motor and inverter, a chiller was installed to transfer heat between the coolant and refrigerant. Increasing the temperature of the chiller coolant from 35 ℃ to 55 ℃ decreased the efficiency by 18.2 % on average due to higher condensing heat source. Increasing the coolant flow rate from 10 liter/min to 20 liter/min did not affect the cooling capacity of the system due to a similar total condensing heat transfer rate at the chiller and the exterior heat exchanger. In future works, heating performance will be investigated by varying the operating conditions to use the chiller's waste heat with an improvement of heating capacity.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.90-94
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• 2006

The waste solution discharged from the LCD manufacturing process contains acids like nitric, acetic and phosphoric acid and metal ions such as Al, Mo and other impurities. It is important to removal of impurities to tess than 1ppm in phosphoric acid to reuse as an etchant because the residual impurities even in sub-ppm concentration in semiconductor materials play a major role on the electronic properties. In this study, we have been clearly established that a mixed system of solvent extraction, diffusion dialysis and ion-exchange technique, which made individually the most of characteristics is developed to commercialize in an efficient system for recovering the high-purity phosphoric acid. By applying vacuum evaporation, the yield of the process are almost 99% removal of nitric acid and acetic acid was achieved. And by applying the solvent extraction method with tri-octyl phosphate(TOP) as an extractant, the removal of acetic and nitric acid from the acid mixture was achieved effectively at the ratio O/A=1/3 with four stages and the stripping of nitric acid from organic phase is attained at a ration of O/A=1 with six stages by distilled water. About 97% and 76% removal of Al and Mo were achieved by diffusion dialysis. Essentially complete less than 1ppm removal of Al, Mo by using ion exchange ion resin and purification of the phosphoric acid was obtain.

• Journal of Navigation and Port Research
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• v.33 no.1
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• pp.57-63
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• 2009

In order to effectively isolate the marine wastes with an effluent standard, the pretreatment process is required to isolate solid materials from the liquid-solid mixed wastes. The more effective the pretreatment becomes, the more processing capacity of posttreatment will be improved and process facilities will be downsized. In this paper, we suggested the vibrating reverse-slant screen, investigated the optimal vibration frequency and vibrator installation angle for the separation of the liquid solid mixed wastes. Several experiments for separation efficiency were conducted under the condition of various vibration frequency($35{\sim}60Hz$, 5Hz interval) and vibrator angle($0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $90^{\circ}$) considering the crack of screen. The screen inclination angle is set up the gradient as $3^{\circ}{\sim}5^{\circ}$ through the preliminary experiments. Also, we made two types of screen(respectively rectangle and square screen). The separation device has shown the optimum efficiency at vibrator angle $0^{\circ}$ and vibration frequency 60Hz, and has no relation with the shape of screen. And the proposed technology is verified by comparing with quantity of suspended solids before and after filtration.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.7
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• pp.778-787
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• 1999

이제까지 대부분의 다중 에이전트 시스템에서는 에이전트 사회에 속한 모든 응용 에이전트를 작업 요청에 관계없이 처음부터 구동시킨다고 가정하였다. 이러한 에이전트 정적 구동 방법은 에이전트 관리를 단순하게 해주는 이점을 제공하지만 워크플로우 관리나 전자상거래와 같이 매우 많은 수의 에이전트로 구성되는 응용 분야에서는 시스템 과부하와 자원의 낭비 등 많은 문제점을 초래한다. 동적 에이전트 관리는 이에 대한 해결책으로 아주 많은 수의 에이전트를 포함하는 다중 에이전트 시스템에서 현재 수행중인 작업에 관련된 에이전트만을 선별하여 구동시키고, 작업이 끝난 에이전트는 종료시킴으로써 자원의 낭비를 막고 에이전트간의 상호작용 시에 요구되는 에이전트 통신의 복잡도 부담을 감소시키는 효과를 낸다. 본 논문에서는 자바로 에이전트 관리 시스템을 구현하고, 이 관리 시스템을 통해 각기 다른 언어로 개발된 응용 에이전트가 분산된 환경에서 상호 협력을 통해 작업을 수행할 수 있는 기법을 제안한다. 사용자나 다른 에이전트의 요청으로 에이전트를 동적으로 수행시키기 위해 다른 언어로의 확장을 가능하게 하는 Java Native Interface(JNI)를 사용한 기술 및 이러한 이질적인 에이전트간의 원활한 통신을 위해서 KQML 언어 인터페이스를 통한 통신 기능을 제안한다. 이질적 에이전트의 동적 관리를 가능하게 함으로써 다중 에이전트 시스템의 자원 이용 효율성과 확장성을 높이고 다양한 환경 변화에 대한 적응성과 개선된 협동능력을 제공한다.Abstract It has been assumed that all application agents in a multi-agent system are pre-invoked and remain active regardless of whether they are actually used. Although this kind of static agent invocation simplifies the management of agents, it causes several problems such as the system overload and a waste of resources, especially in the areas of the workflow management and the electronic commerce that consist of tens and even hundreds of application agents. A solution for these problems is the scheme of dynamic agent management that selectively invokes only agents that are actually requested and terminates them when they are no longer needed. This method prevents a waste of system resources and alleviates the complexity of agent communications.This paper proposes an agent management system implemented in Java that supports interactions between application agents that are developed using different languages. Dynamic agent invocation is accomplished by Java Native Interface(JNI) that links two heterogeneous methods, and by KQML language interface that facilitates the communications between heterogeneous agents. This scheme of dynamic agent management provides efficient resource usage, easy extensibility, dynamic adaptibility to changes in the environment, and improved cooperation.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.80-92
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• 2007

IPTV Services that is representative union service of broadcasting and telecommunication need guarantee of QoS, efficiency of multicasting, and hish bandwidth on the network. Because typical TDM based metro transport network was designed by transporting fixed voice traffic with stable and recovering method, it has a defect of bottleneck and a waste of bandwidth for acceptance of data traffic with burst feature and then all of data are treated equally at the transport network because it cannot classify between advanced high end service and best effort low end service. for completely resolving this kind of problem about increasing burst traffic and QoS issues, firstly we need to new design for transport network. This paper presents transformation method from TDM based metro transport network to packet based transport network and advantage and effectiveness of packet based transport network and also indicates technical factor and characters about method of packet transport system. As a result of research, the Packet Transport System, which is a transmission network for packet delivery, take in not only a specific character of legacy TDM but QoS, Multicast and high bandwidth, then, it is able to keep an effective bandwidth and a stabilized performance of packet transmissions. Additionally, if a fault be occurred on an optical link, the system is able to guarantee a differential QoS by an each service class using an algorithm to make certain of a traffic existence and contain a protective mechanism.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3502-3509
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• 2010

Streaming service in the wireless mobile network environment has been a very challenging issue due to the dynamic uncertain nature of the channels. Overhead such as congestion, latency, and jitter lead to the problem of performance degradation of an adaptive multi-streaming service. This paper proposes a AMSS (Adaptive Multi-level Streaming Service) mechanism to reduce the performance degradation due to overhead such as variable network bandwidth, mobility and limited resources of the wireless mobile network. The proposed AMSS optimizes streaming services by: 1) use of fuzzy similarity metric, 2) minimization of packet loss due to buffer overflow and resource waste, and 3) minimization of packet loss due to congestion and delay. The simulation result shows that the proposed method has better performance in congestion control and packet loss ratio than the other existing methods of TCP-based method, UDP-based method and VBM-based method. The proposed method showed improvement of 10% in congestion control ratio and 8% in packet loss ratio compared with VBM-based method which is one of the best method.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.449-453
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• 2009

This study focused on the content characteristics of regulated hazardous substances in specific wastes. Regulated heavy metal such as Cu, Pb, Cd analyzed the 108 waste samples that it choice from the representative facilities. Analytical method used content test method, suggested on the basis of analytical method of developing country, and the results as compared with limited standard in Austria Petroleum, primary metalworking and electronic industry had high content of Cu more than 100 mg/kg of Austria limited standard. Pb detected high level concentration the sample that dust producted at Primary metalworking industry. In case of total Cr was show that high content at KSIC 18, 19, 23 etc but result analyzed Cr(VI), it was shown that high level at dust producted from sewing clothes and fur industry.

• Journal of Digital Contents Society
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• v.16 no.2
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• pp.197-205
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• 2015

These days due to the introduction of the subject classroom system, the classrooms for the subject are arranged and various advanced educational equipment is provided in the classroom such as the actual object image processor, electronic blackboard, and educational photographer which are helpful to the class. With the increase of these equipments, the number of remote controller of individual educational equipment also increases, therefore it is complicate to manage the remote controllers and teachers need to learn the usage of them. So the system supports a remote control for managing the educational equipment by the one remote controller and the instructional supplement. The system consists of the hardware which is similar to popular remote controller and the software which is installed on the teacher's PC and supports controlling the educational equipments, recording the instruction, writing on the blackboard, and automatic power off of the equipment. By introducing the system the teacher could reduce the time consumed by the equipment's control and useless electric waste.

• Journal of the Korea Society of Computer and Information
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• v.19 no.8
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• pp.19-26
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• 2014

Analysis of influential factors on water consumption in households will help predicting the water demand of end-use in household and give an explanation to cause on the change of trend. In this research, the data are gathered by radio telemetry system which is combined electronic flow-meter and wireless communication system in 140 household in Korea. Using this data, we estimate for each residential type to determine liter per capita day. we used real data to predict bathtub and washbowl water-uses and compared the ordinary least square regression model and autoregressive regression error model. The results of this study can be applied in the planning stages of water and waste water facilities.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.563-568
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• 2016

In this study, experiments were conducted to evaluate the performance of a heat pump system. A heat pump system with an air as heat source is adapted as reference. The developed system uses a plate heat exchanger an evaporator to absorb heat from a stack of fuel cell driven electric vehicles. Hence, the system functions as a water source heat pump system. The results indicated that the; power consumption increased with the rotational speed of the compressor. A system performance($COP_h$) of 2.03 at an electronic expansion valve(EEV) openings of 25% and a compressor speed of 1200 rpm was observed in the reference system. However, at the same compressor speed, the $COP_h$ of the water source heat pump system corresponded to 9.42 at an EEV openings of 75%. It was found that the water source heat pump system exhibited the highest performance at a water temperature of $50^{\circ}C$.