• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.111-111
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• 2017

• Annual Conference of KIPS
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• 2003.11c
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• pp.1433-1436
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• 2003

현재 웹페이지들 대부분은 자료를 데이터베이스에 저장하고 클라이언트측의 특정페이지 요구에 데이터베이스에 연결해 요청에 맞는 리소스를 찾아서 클라이언트측에 다시 보내주는 형식을 취하고 있다. 이러한 일련의 과정 중에서 데이터베이스와 커넥션을 맺는 부분은 매우 많은 시간이 걸리는 작업이다. 본 연구에서는 데이터베이스 접속과 해제를 JDBC Connection Pool 기법을 이용하여 최대한 줄임으로써, 같은 시간에 처리할 수 있는 DBConnection의 성능을 최대한 향상시켰다.

• Journal of applied mathematics & informatics
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• v.25 no.1_2
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• pp.389-405
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• 2007

In this paper, we study a k-out-of-n system with single server who provides service to external customers also. The system consists of two parts:(i) a main queue consisting of customers (failed components of the k-out-of-n system) and (ii) a pool (of finite capacity M) of external customers together with an orbit for external customers who find the pool full. An external customer who finds the pool full on arrival, joins the orbit with probability ${\gamma}$ and with probability $1-{\gamma}$ leaves the system forever. An orbital customer, who finds the pool full, at an epoch of repeated attempt, returns to orbit with probability ${\delta}\;(<\;1)$ and with probability $1-{\delta}$ leaves the system forever. We compute the steady state system size probability. Several performance measures are computed, numerical illustrations are provided.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1906-1911
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• 2007

It has been well known that pool boiling CHF in nanofluids compared to pure water significantly increase due to the deposition of nanoparticles on heater surface. This study concerns the characteristics of the nanoparticle deposition layer and its influence on CHF. Pool boiling experiments were carried out with 0.01vol.% water-$TiO_2$ nanofluids to obtain various nanoparticle-deposited heaters. CHF on the prepared heaters was measured during pool boiling in pure water. The heater surfaces were visualized using scanning electron microscope (SEM) and also characterized using contact angle and capillarity. The results showed that the CHF enhancement in nanofluids was completely dependent upon the structural and physicochemical characteristics of the nanoparticle deposition layer.

• Electronics and Telecommunications Trends
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• v.15 no.4 s.64
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• pp.64-76
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• 2000

정보기술분야의 국제 표준화 기구인 ISO/IEC JTC1에서 주도하여 추진하고 있는 MPEG 표준화가 성공적으로 진행되면서 이의 원활한 시장 적용을 위하여 복잡한 체계로 구성되어 있는 MPEG 기술표준과 연관된 다수의 특허권 처리를 위한 구체적인 조화 방안이 필요하게 되었다. 이는 또한 MPEG 기술의 특허권자가 많기 때문에 다자간의 협상이 요구되는 사안이었다. 이러한 문제 해결을 위하여 MPEG-2 표준의 경우 1990년대 초반부터 이 기술의 주요 개발 업체들간에 표준화의 추진과는 별개의 활동으로서 협의체를 구성하여 복잡한 특허권 관리를 위한 전문적인 기구의 설립을 검토하기 시작하였다. 이를 위한 기반으로 라이센싱의 일원화를 실현하는 특허 POOL을 구축하여 1996년 5월에 MPEG LA를 설립하기에 이르렀다. 이러한 MPEG LA는 공정경쟁에 위배되지 않는다는 법적인 승인을 거쳐 1997년 포트폴리오 라이센스를 공표함으로써 그 본격적인 활동을 펼쳐나가고 있다. 본 고는 표준화와 관련된 특허권 활용의 관점에서 획기적 사건이 되고 있는 MPEG LA의 활동 현황을 분석한 것으로서 특히 그 특허 POOL의 내역과 로열티 구조를 중점적으로 하여 포트폴리오 라이센스의 체계를 소개한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.143-151
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• 2000

In order to clarify the effect of tube orientation on pool boiling heat transfer, the experiments were carried out for the saturated pool boiling of water at atmospheric pressure. Through the tests a series of data sets for heat flux versus wall superheat has been obtained using various combinations of tube diameters (D=9.7 $\~$25.4mm)， surface roughness ($\varepsilon$=15.1$\~$60.9nm)， and tube orientations (horizontal and vertical). ηei experimental results show that the slope of heat flux versus wall superheat becomes smaller than that of the horizontal tube as the surface roughness decreases from $\varepsilon$=60.9 to $\varepsilon$=15.1nm. Such that， two curves for the horizontal and vertical tubes cross each other in accordance with surface roughness and the crossing point can be suggested as q" = ‘-4.768+1.334$\varepsilon$+0.055${\varepsilon}^2$.

• Journal of Mechanical Science and Technology
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• v.14 no.8
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• pp.851-860
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• 2000

Temperature field and cooling rate are important parameters to influence the properties of clad layer and the heat affected zone. In this paper the temperature field and cooling rate of laser cladding are studied by a two-dimensional time-dependent finite element model. Experiment has been carried out by Nd:YAG laser cladding with wire feeding. Research results indicate that at the beginning of cladding, the width and depth of melt pool increase with cladding time. The cooling rate is related to position, cladding time, cladding speed, and preheating temperature. The temperature near melt pool changes rapidly while the temperature far from melt pool changes slowly. With the increase of cladding time, cooling rate decreases. The further the distance from the melt pool, the lower the temperature and the slower the cooling rate. The faster the cladding speed, the faster the cooling rate. The higher the preheating temperature, the slower the cooling rate. The FEM results coincide well with the experiment results.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.89-95
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• 1997

Welding technique is widely applied to general industry such as pressure vessel for chemical plant, pipe system, heavy industry, and automobile. There are some points which must be considered when robot system is used in welding automation process for productivity improvement. Welding quality is governed by heat input, and this quantity can be different according to shape, property, and thick of material . For desired heat input , weld input parameters such as welding voltage, current, and welding velocity must be determined with those consideration. Until now these parameters have been determined mainly by experience of operator. In this study, the size of welding zone was predicted by fuzzy rules were constructed from the relation between welding variables and weld pool size. Inverse model method which welding control input for welder is determined with optimum voltage and current by fuzzy controller is validatied by computer simulation.

• Journal of the Korea Safety Management & Science
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• v.6 no.2
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• pp.155-165
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• 2004

It is needed to develop on-line real time management and RFID-PPS(Radio Frequency Identification-Pallet Pool System) by putting information technology. Additionally, it is possible to figure out the flow of all the materials loaded on the RFID pallet; product, material, raw material immediately, so that epoch-making management is possible and it contributes to the reduction of logistics cost because there are little loss or outflow of pallet. The materials flow is getting speedy and inventory is decreasing in the logistics process, and also bad inventory and loss problems are prevented. As a result, not only logistics cost of company but also national logistics cost is decreased. Thus it contributes to the strength of national competitiveness.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.12
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• pp.1204-1208
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• 2010

In this paper, we propose a flash memory wear-leveling scheme that makes use of meta-data storage region as a regulation pool. By concentrating program and erase operations on the blocks with lower erase counts in the regulation pool, the proposed scheme achieve an even wear-leveling in a simple and efficient way. Experiments with an implementation of the proposed scheme in RS-FTL showed that the erase count deviation is reduced by around 40% through the erase count regulation.