• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.89-90
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• 2023

본 논문에서는 HAProxy를 이용하여 웹 서버를 제어하는 모델을 제안한다. 인터넷이 다양한 분야로 확대됨과 다양한 디바이스의 활용으로 이용자 및 이용 시간, 이용 빈도가 증가하고 있다. 서버를 운영하는 과정에서 서비스 중간에 서버를 제외하고 투입해야 하는 상황들이 발생하고 있다. 이에 본 논문에서는 DNS에서 서버 IP를 투입 및 제외를 통해 이뤄지고 있는데, DNS 서버를 직접 운영하고 있지 않을 경우 처리시간이 증가한다는 불편한 점을 DNS 서버와 웹 서버 사이에 HAProxy 서버를 추가하여 웹 서비스 운영을 유연하게 처리하여 장애 등의 상황에서 빠르게 대처하여 웹 서비스를 사용하는 사용자의 불편함을 감소시킬 수 있을 것으로 기대할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.860-862
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• 2007

최근 IT분야에서는 URC(Ubiqutious Robotic Companion)라는 새로운 개념의 로봇 시스템에 대한 연구가 이루어지고 있다. 본 논문에서는 NXT Mindstorm을 이용한 길안내 네트워크 로봇 시스템을 제안한다. LEGO brick을 이용해 이동 가능한 로봇을 제작하고 RFID 시스템을 장착한다. 로봇의 이동은 네트워크 서버를 통해 NXT Mindstorm으로 직접 전달하여 제어한다. 또한 로봇의 경로이탈이 발생하면 RFID 리더는 Tag의 정보를 읽어 네트워크 서버로 전달하며, 네트워크 서버는 전달받은 데이터 처리 후 NXT Mindstorm으로 명령을 전달하여 제어한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.222-225
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• 2024

전통적 프로그래밍 언어인 C/C++는 시스템 프로그래밍 언어로 널리 사용되고 있으며, 이는 저수준 메모리 제어와 하드웨어 상호작용 등의 특성 때문이다. 하지만 C/C++가 가지고 있는 특성중 하나인 저수준 메모리 제어는 프로그래머가 직접 메모리를 관리해야한다. 다양한 메모리 버그들중에서 특히 Use-after-free버그는 오래전부터 현재까지 해결되지 않은 버그로써 존재하고 있으며, 이는 프로그래머가 수동으로 메모리를 관리함으로써 발생한다. 이 버그를 예방 및 감지하기 위한 연구가 현재까지도 활발하게 진행되고 있다. 이 버그를 차단 및 감지하는 연구들의 동향을 분석하여 앞으로의 관련 연구의 지속적인 필요성을 제시한다.

• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.103-113
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• 2005

In the present study, the Direct Inelastic Design (DID) for steel structures developed in the previous study was improved to expand it applicability. The proposed design method can perform inelastic designs that address the design characteristics of steel structures: Group member design, discrete member sizes, variation of moment-carrying capacity according to axial force, connection types, and multiple design criteria and load conditions. The design procedure for the proposed method was established, and a computer program incorporating the design procedure was developed. The design results from the conventional elastic method and the DID were compared and verified by the existing computer program for nonlinear analysis. Compared with the conventional elastic design, the DID addressing the inelastic behavior reduced the total weight of steel members and enhanced the deformability of the structure. The proposed design method is convenient because it can directly perform inelastic design by using linear analysis for secant stiffness. Also, it can achieve structural safety and economical design by controlling deformations of the plastic hinges.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.4
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• pp.351-358
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• 2015

In the recent times, the use of gasoline direct injection (GDI) engines has been regarded as a means of enhancing conformance to emission regulations and improving fuel efficiency. GDI engines have been widely adopted in the recent years for their better engine performance and fuel economy compared to those of conventional MPI gasoline engines. However, they present some disadvantages related to the mass and quantity of particulate matter generated during their use. This study investigated the nanoparticle characteristics of the particulate matter exhausted from a GDI engine vehicle installed with different types of gasoline particulate filters, after subjecting it to ultra-lean burn driving conditions. Three metal foam and metal fiber filters were used for each experimental condition. The number concentrations of particles were analyzed for understanding their behavior, and the reduction characteristics were obtained for each type of filter.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.837-844
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• 2014

Automotive manufacturers have recently developed various technologies for improving fuel economy and satisfying enhanced emission regulations. The ultra-lean direct injection engine is a promising technology because it has the advantage of improving thermal efficiency through the deliberate control of ignition. A conventional LPG engine has been redesigned to an ultra-lean-burn LPG direct injection engine in order to adopt combustion system of ultra-lean-burn. This study is aimed at investigating the effect of a change in the compression ratio on the performance and emission characteristics of a lean-burn LPG engine. The fuel consumption, heat release rate, combustion pressure, and emission characteristics are estimated depending on changing the effect of compression ratio. When the compression ratio is increased, it is difficult to improve the fuel consumption owing to an unstable combustion state, but the total hydrocarbon and nitrogen oxide emissions are reduced.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.80-80
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• 1999

플라즈마 디스플레이 패널(PDP)의 공정을 간단히 하기 위하여 포토레지스트, ITO, 격벽재료를 Ar+ laser(λ-514 nm, CW)와 Nd:YAG laser(λ=532, 266nm, pulse)로 직접 패터닝 하였다. 레이저에 의한 포토레지스트의 패턴결과, 아르곤 이온 레이저의 포토레지스트 가공의 반응 메카니즘은 레이저 빔의 열에 의한 시료 표면의 국부적인 온도상승에 의한 용융작용이며, 그 결과 식각 후 형성된 패턴의 단면 모양도 레이저빔의 profile과 같은 가우시안 형태를 나타낸다. Nd:YAG 레이저의 4고조파(532nm)를 이용한 경우 200$\mu\textrm{m}$/sce의 주사속도에서 포토레지스트를 패턴하기 위한 임계에너지(threshold energy fluence) 값은 25J/cm2이며, 약 40J/cm2의 에너지 밀도에서 하부기판의 손상이 발생하기 시작하였다. 글미 1은 Nd:YAG 레이저 4고조파를 이용하여 포토레지스트를 식각한 경우 SEM 표면사진(위)과 단차특정기에 의한 단면형상(아래)이다. ITO 막의 레이저에 의한 직접 패턴 결과, ITO 막은 레이저 펄스에 의한 급속 가열 및 증발에 의한 메커니즘으로 식각이 이루어지며, 레이저 파장에 따른 광흡수 정도의 차이에 의해 2고조파 (532nm)에서 ITO 막의 가공 품질이 4고조파(266nm)에 비해 우수하며 패턴의 폭도 출력에 따라 제어가 용이하였다. 그림 2는 Nd:YAG 레이저 2고조파를 이용하여 ITO를 식각한 경우 SEM표면 사진(위)과 단차측정기에 의한 단면형상(아래)이다. 격벽 재료의 레이저에 의한 직접 패턴 결과, Ar+ 레이저(514nm)는 출력 밀도 32NW/cm2에서 격벽을 유리 기판의 경계면까지 식각하였다. Nd:YAG 레이저(532nm)는 laser fluence가 6.5mJ/cm2에서 격벽을 식각하기 시작하였으며, 19.5J/cm2에서 유리기판의 rudraus(격벽 두께 130$\mu\textrm{m}$)까지 식각하였다.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.1-8
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• 2011

This article proposes a hybrid approach involved in determining the size of stormwater control facilities as part of a very large scale urban retrofit project. The objective of the proposed hybrid approach is to restore the pre-development hydrologic cycle. Firstly, an appropriate IETD is determined to isolate single storm events from the continuous rainfall record. Then, using the NRCS-CN method, direct runoff and infiltration volume are computed for every storm events. Long-term statistics of direct runoff and infiltration volume are analyzed in each case of pre-development, post development, post development with detention only, and post-development with the proposed hybrid approach. In order to preserve long-term statistics of direct runoff and infiltration volume in the case of pre-development, the size of detention and infiltration-based retention are estimated using the genetic algorithm. The result shows that the proposed hybrid approach is very useful for restoring statistics of natural direct runoff and infiltration volume.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1255-1262
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• 2012

Look into the nuclear power plant of Wolsong currently, it is controlled in order to required operating pressure with PI controller. PI controller has a simple structure and satisfy design requirements to gain setting. However, It is difficult to control without changing the gain from produce changes in parameters such as loss of the valves and the pipes. To solve these problems, the dynamic change of the PI controller gain, or to compensate for the PI controller output is desirable to configure the controller. The aim of this research and development in the parameter variations can be controlled to a stable controller design which is reduced an error and a vibration. Proposed PI/NN control techniques is the PI controller and the neural network controller that combines a parallel and the neural network controller part is compensated output of the controller for changes in the parameters were designed to be robust. To directly evaluate the controller performance can be difficult to test in real processes to reflect the characteristics of the process. Therefore, we develope the simulator model using the real process data and simulation results when compared with the simulated process characteristics that showed changes in the parameters. As a result the PI/NN controller error and was confirmed to reduce vibrations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.2
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• pp.34-44
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• 2007

Many urban cities deployed ITS technologies to improve the efficiency of traffic operation and management including a real-time franc control system (i.e., COSMOS). The system adopted loop detector system to collect traffic information such as volume, occupancy time, degree of saturation, and queue length. This paper investigated the applicability of detector information within COSMOS to represent the congestion level of the links. Initially, link travel times obtained from the field study were related with each of detector information. Results showed that queue length was highly correlated with link travel time, and direct link travel time estimation using the spot speed data produced high estimation error rates. From this analysis, a procedure was proposed to estimate congestion level of the links using both degree of saturation and queue length information.