• Journal of KIISE:Computing Practices and Letters
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• v.5 no.5
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• pp.533-542
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• 1999

웹은 지금까지의 문자 위주의 응용에서 벗어나, 그림, 동영상과 같은 멀티미디어 자료를 브라우저를 통해 접근할 수 있도록 하여, 점차 많은 응용분야에서 사용되고 있다. 최근에 들어서는 데이타베이스와 웹의 연동을 통해, 보다 다양하고, 양질의 웹 서비스를 지원하고자 하는 노력으로, 많은 연구자들이 웹 통로에 대한 많은 연구로 좋은 결과를 내고 있다. 그러나 웹과 데이타베이스의 연동에 있어 필요한 웹 트랜잭션 처리시 발생하는 문제에 있어서는 아직까지 만족할 만한 연구결과가 제시되지 않고 있다.본 논문에서는 웹 통로에서 웹 트랜잭션 처리를 위한 시스템인 WebTP를 제안하고, 이를 구현하였다. WebTP는 워크, 워크-전역변수 등을 도입하여, 웹 응용 단위에서의 저장점 설치와 부분 철회와 트랜잭션 상태 관리 기법을 제공하여, 시스템의 가용성과 안정성을 높이며, 구조적인 웹 응용작성이 가능토록 하여, 복잡한 웹 응용 개발을 돕는다.Abstract Enabling users to access multi-media data like images and motion pictures, in addition to the traditional text-based data, Web becomes a popular platform for various applications. Recently, many researchers have paid a large amount of works on integrating Web and databases to improve the quality of Web services, and have produced many noticeable results on this area. However, no enough research results have been presented on processing Web transactions that are essential in integrating Web and databases.In this paper, we have designed and implemented WebTP, which is a Web transaction processing system for Web gateways to databases. WebTP, by introducing work and work-global-variables, provides a more robust state management, supports application-level savepoints and partial rollbacks. It also nhances productity by providing a modular way to develop Web applications.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.63-70
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• 1983

Recently, many studies for developing the underwater welding techniques have been carried out in the advanced countries as a manufacturing process and a repairing method according as a great deal of interest in development for various marine industrial fields has been gradually increased. But no study on such underwater welding is available at present in our country. In this study, underwater welding was carried out for welding of domestic structural steel plates (SM41A) of 10 mm thickness, using six types of domestic coated arc welding electrodes on a self-made gravity type underwater welding device, resulting in investigation for the underwater weldability of the domestic structural steel plates as well as for the underwater welding properties and practicability of the domestic welding electrodes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.84-92
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• 2010

This paper presents the influence of the underground structure (such as cavern and tunnels) behavior according to the rock joint orientation and underground cavern size. In order to perform this research, numerical and experimental studies are carried out. Stress aspect was assessed by quantitative according two kind of factor. In the experimental study, the laboratory model tests are performed in the several ground conditions with different underground cavern size. The results obtained from the model tests are also verified and evaluated using the numerical analysis. Due to the underground cavern, it is found from this study that the stresses developed in archcrown, side wall of underground are increased with increasing the underground cavern size. It is also investigated that the rock joint direction is one of main influence factor as risk factor, to maintain the underground cavern stability. It may be expected that this research will provide the very useful information to evaluate the underground cavern stability.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.2
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• pp.131-139
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• 2012

In this study, the numerical analysis has been conducted in order to check behavior characteristics of liner plate made of corrugated steel from urban small sized tunnel excavation. The analysis was conducted with five kinds of conditions like 5 m, 10 m, 15 m, 20 m and 25 m to examine the behavior characteristics of liner plate according to the depth of cover. Analysis results showed that the maximum axial stress and the maximum displacement occurs in the lower end of the member, and the maximum shear stress occurs in the upper part of the member. Also, change of displacement, stress shearing stress of liner plate based on various depth of cover are existed, but the difference is slight, and by increasing depth of cover, structural stability is gradually ensured.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.28-35
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• 2018

In order to analyze the flammability limit and structure of the gaseous methane-gaseous oxygen diffusion flame formed through a shear coaxial injector, combustion experiments were carried out according to the condition of injector recess and propellant mass-flow rate. As a result, it was confirmed that stable anchored flame was observed even at the high oxygen Reynolds number as the propellant momentum flux ratio increased, and that the recess had no significant influence on the flame shape and flammability limit. The anchored flame visualized through a chemiluminescence showed the maximum OH radical emission intensity at a specific position, irrespective of the propellant injection condition, and the radical intensity was greatly reduced by the injector recess.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.412-419
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• 2006

We design and fabricate an autostigmatic null lens system assembled in a fixed tube mount in order to evaluate the shape of an aluminum hyperbolic mirror with the diameter of 300 mm and the f-number of 1.98, which is fabricated by a high precision aspherical DTM (diamond turning machine). Also, we evaluate the degree of shape of the aspherical mirror by this autostigmatic null lens testing method. The autostigmatic null lens system assembling in a fixed tube mount has several advantages of light weight, good mechanical stability, etc. The permissible fabricating limits of null lenses and a mount are determined by considering various tolerances to assure the measurement reliability.

• Korean Journal of Optics and Photonics
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• v.31 no.1
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• pp.31-36
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• 2020

We propose a band-switchable terahertz metamaterial based on an etched vanadium dioxide (VO₂) thin film. A line of etched VO₂ thin film was placed in the center gap of the split square-loop shape for the tunability of the metamaterial. The resonance frequency of the metamaterial can be switched from the 1.4 THz band to the 0.7 THz band, according to the insulator-metal phase transition in the VO₂ thin film. The absolute difference in the transmittance of the metamaterial was 78.5% and 65.8% at 0.7 THz and 1.4 THz respectively, according to the band switching. The differential phase shift was around 90°, and the transmittance was stably maintained between 40% and 60% in the middle band of the two switchable resonance-frequency bands.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.8-14
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• 2021

Post-tensioned prestressed concrete members experience immediate prestress losses as well as time-dependent prestress losses such as creep, dry shrinkage and relaxation. In addition, the stress of the upper and lower parts of the member changes due to the change in dead load due to the replacement of the upper slab and/or pavement. Such changes in fiber stress may affect the safety of the member, and it is necessary to adjust the prestressing force. Therefore, in this study, a screw type of re-tensioning post-tension kit is proposed, and it is verified that the safety against load and the stability against strain are satisfied through the load transfer test specified in EAD160004 and KCI-PS101.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.594-601
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• 2021

In order to expanding of the use of steel slag, a by-product of steel industry, as a road paving construction material, this present study confirmed the possibility of the rust formation of steel slag aggregate and evaluated the durability performance and the noise reduction characteristics of asphalt concrete mixture. As a result of conducting the rust formation test of aggregate, no rust was observed in both aggregate, so it is judged that the possibility of rust formation in the actual road water environment is very low. As a result of performing the moisture resistance test, all mixtures showed a tensile strength ratio exceeding 85%, satisfied the standard as asphalt mixture. In addition, the sound absorption coefficient of the steel slag aggregate mixture was measured to be higher than that of the general aggregate mixture. Accordingly, it is speculated th at th e steel slag aggregate mixture can more effectively respond to road noise reduction than the general mixture.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.39-42
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• 2019

We report on the design of oil-water separators and the selection of materials for the effective application of highly selective membranes fabricated by commercial PET (polyester) fabrics. The waterproof ability of PET fabrics was optimized to improve the separation selectivity. The density of individual PET fabrics should be over $60g/m^2$, and the multi-layered structure is more favorable for the waterproof ability together with maintaining the removal efficiency. For the continuous adsorption and removal process, the rotating perforated cylinder was selected, and covered with membranes. Furthermore, more improved and stable removal efficiency was obtained by installing floating baffles which forces the oil content to move toward membranes.