• Proceedings of the KSME Conference
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• 2003.11a
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• pp.49-54
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• 2003

Scale is formed when hard water is heated or cooled in heat transfer equipments such as heat exchangers, condensers, evaporators, cooling towers, boilers, and pipe walls. When scale deposits in a heat exchanging surface, it is traditionally called fouling. The objective of the present study was to compare the fouling characteristics of river and tap water in a heat exchanging model. FromtheSEM analyses for tap water the $calciteformofCaCO3_{3}$ was formed. For river water, however, the $aragoniteCaCO_{3}$ wasformed.In order to investigate velocity effects on the fouling characteristics in the heat exchanging model, the inlet velocity was varied with 0.5, 1.0 and 1.5 m/s, respectively. The fouling characteristics of river water were quite different from those of tap water. For the case of the 'velocity of 1.5m/s', the overall heat transfer coefficient was reduced up to 26% than that of the 'velocity of 0.5m/s'

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1473-1478
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• 2003

Scale is formed when hard water is heated or cooled in heat transfer equipments such as heat exchangers, condensers, evaporators, cooling towers, boilers, and pipe walls. When scale deposits in a heat exchanger surface, it is traditionally called fouling. The objective of the present study is to investigate the formation of fouling in a heat exchanging system. A lab-scale heat exchanging system is built-up to observe and measure the formation of fouling experimentally. Water analyses are conducted to obtain the properties of HAN river water. In the present study a microscopic observation is conducted to visualize the process of scale formation. Hardness of HAN-river water is higher than that of tap water in Seoul.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.417-422
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• 2008

The DC high speed circuit breaker used in Seoul Metro for line no.1.2 is Japan HITACHI and FUJI breaker, and for line no.3.4 is Whipp & Bourne MM74 breaker from UK. The years that each breakers made are 1973(line no.1), 1984(line no.3.4), So that equipments are superannuated. Nowday the for equipment exchanging is executing, equipment for exchanging were used the Secheron breaker from Swiss. but now the Intec breaker made in Korea is used. The RTU of supervisory control and data acquisition system have the capabilities that can observe, control and work the installation efficiently. In this paper, as summarizing the solving process of problem that happened the SCADA system when old-equipment exchange and concerned point for logical supervision and control of reservation factors and equipment, I'll provide the direction that can do receiving-process of control-equipment, progressed with the exchange of old-electronic equipment.

• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.378-381
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• 2014

We studied the pasteurization effect of the microorganism involved in the water, using ion-exchanging filter made of the Radiation Induced Grafted Polymerization. This ion-exchanging filter is made by the graft polymerization of GMA, after irradiation of electron beam to the non-woven filter. Then, we made the ion-exchanging filter (EtA, DEA, SS) applying ion-exchanging base to the GMA filter. As a result, the density of the ion-exchanging base is shown as 2.38 mol/kg in case of EtA, 1.79 mol/kg in case of DEA and 0.75 mol/kg in case of SS. Through this filter made by this method, we measured the pasteurization power of E. coli. We found very high elimination rate such as log 4.65 in case of SS-dial filter, which is higher as 3.00 times in comparison with EtA, and 1.10 times in comparison with DEA. This data show the result is very excellent comparing with 3,000 CFU/ml. of city water treatment basis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.4
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• pp.349-354
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• 2004

Scale is formed when hard water is heated or cooled in heat transfer equipments such as heat exchangers, condensers, evaporators, cooling towers, boilers, and pipe walls. When the scale deposits in a heat exchanger surface, it is conventionally called fouling. The objective of the present study is to analyze the process of the fouling formation in a heat exchanger according to different types of water using visualization techniques. In order to experimentally investigate the formation of the fouling, this study built a lab-scaled heat exchanging system. Using the visualization techniques of Scanning Electron Microscopy (SEM) and X-Ray diffraction method, the three dimensional configurations of the fouling formation could be successfully obtained. Based on the experimental results, it was found that the configurations of the fouling formation were different when using tap water compared to river water.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.109-112
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• 2002

SNMP is generally used protocol for network management. SNMP need MIB for exchanging management information But, method for sharing MIB is not automatic. General MIB sharing architecture is done by network management operator by manually. In this paper we describe exchanging MIB automatically using meta-MIB. We will formalize SMI as MIB structure. This meta MIB represent information about MIB of NE Agent. Meta MIB has Information of object in the MIB, Structure and index information fur columnar object, meaning of subtype at INTEGER syntax. Also, trap related information is represented too. In this paper, MIB information is represented as instance of meta MIB. This architecture will provide a method for automatic MIB exchanging

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.4
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• pp.209-214
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• 2009

The purpose of this study is to investigate the effect exchanging water supply on the' rainwater in detached house. It is difficult to decide water supply amount for a closet in detached house, Therefore, to obtain water supply for closet in detached house, it used regression equation using 1,569 data of frequency of used closet and during 120 days. In detached house, the frequency of used closet is 14.6 times/day and water supply amount is $219 {\ell}/day$. The optimum rainwater tank size which is decided by regression equation and using weather data is $8.5\;m^3$. The effect exchanging water supply on the rainwater in detached house is up 50%.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.494-496
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• 1998

이 논문은 안전한 통신을 보장하고, 전자결재 기능을 제공하는 SEED(Secure Environment for Exchanging Digital Signatures)의 설계 구현에 대해 기술한다. SEEDS는 일반 기업이나 단체에서 근거리망을 통해 서류를 결재하고 교환하는데 개발된 전자결재스템이다. 따라서 SEEDS는 사무환경 특성에 적합한 시스템 구조와 암호화 알고리즘을 기반으로 하는 중재결재 방식을 사용하며, 결재된 서류뿐만 아니라 통신 메시지의 보안을 위해 새롭게 개발한 키 교환 메시지 전송 프로토콜을 사용한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.149-157
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• 2003

Recently, the Internet enhanced by development of IT makes the processing and exchanging of information, As the Internet is sending and receiving digitized documents over the Internet e-mail system. The security of document information is being threated when exchanging digitized documents over an open network such as the Internet. The degree of threat is even higher when sensitive documents are involved Therefore, in this paper, the secure e-mail system on a client is designed and implemented in order to make secure exchanging of digitized documents. By using the public key infrastructure in which encrypted mail transmission, proof of delivery and integrity of the message are garanted, unauthorized manipulation, illegal acquisition and mutual authentication problem can be prevented in order to secure the document information which is crucial and sensible when exchanging the digitized document over the Internet. Futhenmore, by using the SET protocol based on public key cryptography, the secure mail system is designed and implemented in order for the users not having any professional knowledge to deal with the system easily and friendly in GUI environment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.6
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• pp.646-651
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• 2004

When the water flowing inside of the heat transfer equipments such as heat exchangers, condensers, and boilers is heated, calcium, magnesium sulfate, and other minerals in the water are deposited and built up for scales on the heat transfer surfaces. When those scales accumulate on the heat transfer surfaces, their performance of the heat transfer become progressively reduced due to the increase of the heat transfer resistance. The mechanism of this reduced heat transfer is called fouling. This study investigated the formation of the fouling in a heat exchanger with river and tap water flowed inside of it as a coolant. In order to visualize the formation of the fouling and to measure the fouling coefficients, a lab-scale heat exchanging system was used. Based on the experimental results, it was found that the formation of fouling for river water was quite different with the formation for tap water.