• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.31-33
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• 2022

등부표는 소형 어선을 포함한 선박의 항로표지에 중요한 역할을 한다. 그러나 야간에 어두워지면 해상에 설치된 등부표의 위치나 번호판 식별이 어려워 소형 어선이나 선박이 등부표에 가까이 접근하는 경우 등부표를 미처 발견하지 못하고 충돌하여 선박이 파손되거나 인명사고가 발생한다. 이 연구에서는 소형 어선이나 선박이 야간에도 등부표의 위치와 번호판을 쉽게 식별할 수 있도록 등부표에 조명장치를 구비하여 충돌사고의 예방과 항로표지서비스를 향상시키는 방법을 분석하고 고안하여 태양광전원을 이용한 방수형 LED조명과 통신모듈IoT를 결합하여 원격디밍 RGB제어 및 조명자가진단기능을 갖추어 야간에 시인성을 높이는 등부표의 윤곽표시조명을 개발하였다.

• Korean Journal of Construction Engineering and Management
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• v.11 no.6
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• pp.111-121
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• 2010

As the customer's interest for sidewalk block in the street or apartment complex is increasing, the materials of block which had been a concrete block exclusively are varied to clay paver, native rock and wood etc. Especially, the sales volume of clay paver which is environment-friendly and ergonomic is dramatically increasing every year with two digits growth rate, however, many problems like "Edge Cracking" "Freezing Breakage" "Bending Breakage" "Joint Gap" are happening frequently within a couple of hours after installation due to the durabilities. Because of the characteristics of Ceramic products, clay pavers are very easy to be broken when they are bumped against each other. In addition, they are relatively fragile by a freezing expansion breakage when exposed to water due to hydrophilic property as well as the intensity and absorptance of the products are varied with small difference from the production process such as production equipment and process control. Therefore, it costs a lot of money to repair the breakdown unless production and installation is carried out according to the strict criteria of the quality control. In this study, the symptoms of breakdown frequently happened in clay paver are classified by each type and finally the solution for this problem in the production of brick, installation and criteria of quality control through compressive strength and absorptance test is suggested.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.11-20
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• 2008

In probabilistic seismic analysis of nonlinear structural system, dynamic analysis is performed to obtain the distribution of the response estimate using input ground motion time histories which correspond to a given seismic hazard level. This study investigates the differences in the distribution of the responses and the failure probability according to input ground motion models. Two types of input ground motion models are considered: real earthquake records scaled to specified intensity level and artificial input ground motion fitted to design response spectrum. Simulation results fir a nonlinear SDOF system demonstrate that the spectrum matched input ground motion produces larger failure probability than those of scaled input ground motion due to biased responses. Such tendency is more remarkable in the site of soft soil conditions. Analysis results show that such difference of failure probability is due to the conservative estimation of design response spectrum in the range of long period of ground motion.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.5
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• pp.326-332
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• 2010

Critical response of seawater pump impeller shaft structure to various exciting loads is a fundamental factor in re-designing of the structure after its functional failure. In this paper, a typical case of the shaft structure's failure is investigated for re-designing purposes. Failure causes of interest are excessive bending moment, fatigue loads and dynamic resonance due to relevant motor rotation and unbalancing of the rotation loads. Static analyses of shaft structure under the conditions of concerned loads are carried out, followed by a dynamic investigation of the effects of resonance between the shaft and the motor on the structure. The relevant structural analyses are carried out using the Finite Element Methods combined with ANSYS code. Based on these, the primary cause for the shaft's structural failure is obtained. It is found that the change of the bending stiffness of the shaft is the primary concern in the re-designing process. A guideline for the re-design process of the seawater pump shaft structure is established, and a re-design scheme of the structure is proposed.

• Journal of Korea Port Economic Association
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• v.25 no.3
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• pp.117-138
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• 2009

Heavy truck traffic causes serious damage to not only environment condition due to the emissions but also pavement condition. In Incheon city area, the highways of the port hinterland suffer from similar problems. Therefore, it is required to develop a policy to solve those problems, which should be under the collective agreement of the truck drivers, local residents, and policy makers. This paper compared the truck traffic volumes and re-pavement construction history for last 4 years and showed the real effect of the heavy truck traffic on the pavement. Furthermore, this study examined the pros and cons of the exclusive truck lane and truck only highway policies and conducted a survey of truck drivers, local residents, and policy makers. Each group showed different preferences for the policies particularly for the question asking the best implementable policy.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.771-776
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• 1998

울진 원전 3,4 호기를 대상으로 MAAP4.0.2 코드를 이용하여 발전소 정전사고를 모의/분석했다. 본 분석에서는 사고진행에 따른 일.이차계통의 상태변화를 원자로용기 파손때까지 상세 파악하였다. 사고관리 관점에서, 발전소 정전사고는 이차측의 대기방출밸브를 통한 강제감압에 의해 사고진행을 완화할 수 있으며 이러한 운전원 조치에 의한 완화효과를 검토하였다 그 결과 감압시작 2시간후에 일차측은 약 24$^{\circ}C$ 의 과냉각도를 보이며 안정되었고. 사고시작 1시간 후부터 3시간 동안의 강제감압이 성공한 경우, 노심노출시간 기준으로 약 2시간의 지면효과가 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.271-278
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• 2008

A study has been conducted on the bulging process of liquid rocket engine nozzle which is essential to the manufacturing regenerative cooling combustion chamber. Mechanical properties of the material used for the bulging were experimentally obtained by tension tests. Deformation of the bulged nozzle was confirmed by a structural analysis. The developed bulging process and the deformation analysis result were confirmed by manufacturing of the bulged nozzle specimens and the bulging test. There has been a bulging failure among 7 bulged specimens due to the necking of the material. The cause of necking was investigated by comparing microstructure of the material. The investigation has revealed grain size of the material has considerable effect on the occurrence of the necking.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.795-800
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• 1998

월성 발전소에서의 중대사고 진행을 예측하고 분석하기 위하여 CANDU 발전소의 중대사고 해석코드인 ISAAC을 이용하여 능동 안전 장치들이 동작하지 않는 발전소 정전사고에 대한 분석을 수행하였다. ISAAC은 사고 관리용 전산코드로 개발된 MAAP4/PWR를 근간으로 월성 발전소의 고유 특성에 관한 모델들을 추가하여 개발되었다 월성 발전소의 경우 칼랜드리아 안의 감속재와 칼랜드리아 볼트 안의 냉각수는 피동 열침원으로, 능동 안전 장치들이 동작하지 않는 중대사고시 노심으로부터의 붕괴열을 제거하여 노심 손상을 지연시킬 수 있다. 발전소 정전사고에 대한 ISAAC 계산 결과 노심 손상후 칼랜드리아 파손까지 약 40 시간이 예상되며, 이 동안에 운전자는 사고를 완화시킬 수 있는 방안을 모색할 수 있다. 따라서, 월성발전소의 피동안전장치는 사고 관리 전략 수립에 중요한 기능을 담당한다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.385-386
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• 2012

기존 뇌서지에 관한 논문은 정보통신 설비 및 전력계통의 대책에 관한 연구가 진행되어 왔으나, SMPS에 관한 연구는 부진하였다. 따라서, 본 논문에서는 조합파 신호발생기를 통하여 서지전압 인가에 따른 플라이백 컨버터에서의 서지전류 경로를 분석한다. 또한, 새로이 발견한 서지전류로 인하여 발생되는 주요 소자파손 원리를 제시한다. 최종적으로 서지경로 상의 실제 측정 결과를 제시하여 제안 방식의 타당성 및 유효성을 검증하였다.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.31-38
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• 2009

The primary objective of this study was to estimate the deterioration degree of jointed concrete pavement which was major concrete pavement type in Korea. First of all, visual survey of concrete pavement was performed to observe deterioration types. In the result of visual survey, the majority of concrete pavement deterioration was investigated in joint area. It is appeared that most of the distresses are durability cracking and joint distress. Second, concrete core specimens were taken from eight locations including good section (4 locations) and bad section (4 locations) based on visual survey. The deterioration reasons of concrete pavement were analyzed with ultrasonic pulse velocity test, splitting tensile strength test, and image analysis for concrete core specimens. Among the image analysis test result for 21 concrete core specimens, only two specimens satisfied the Kansas DOT criteria of spacing factor, $250\;{\mu}m$, and the remains of 19 specimens were estimated to be above $250\;{\mu}m$. The durability factor of concrete was estimated very low. As a result, it was analyzed that the main deterioration reason of the deteriorated jointed concrete pavement was to be freezing and thawing damages.