• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.44-49
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• 2018

This study analyzed the Vulnerability of Network Communication devices when IEMI is coupled with the Network System. An Ultra Wide Band Generator (180 kV, 700 MHz) was used as the IEMI source. The EUTs are the Switch Hub and Workstation, which are used to configure the network system. The network system was monitored through the LAN system configuration, to confirm a malfunction of the network device. The results of the experiment indicate that a malfunction of the network occurs as the electric field increases. The data loss rate increases proportionally with increasing radiating time. In the case of the Switch Hub, the threshold electric field value was 10 kV/m for all conditions used in this experiment. The threshold point causing malfunction was influenced only by the electric field value. The correlation between the threshold point and pulse repetition rate was not found. However, in case of the Workstation, it was found that as the pulse repetition rate increases, the equipment responds weakly and the threshold value decreases. To verify the electrical coupling of the EUT by IEMI, current sensors were used to measure the PCB line inside the EUT and network line coupling current. As a result of the measurement, it can be inferred that when the coupling current due to IEMI exceeds the threshold value, it flows through the internal equipment line, causing a malfunction and subsequent failure. The results of this study can be applied to basic data for equipment protection, and effect analysis of intentional electromagnetic interference.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.4
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• pp.352-357
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• 2012

The ground resonance instability of a helicopter with bearingless main rotor hub were investigated. The ground resonance instability is caused by an interaction between the blade lag motion and hub inplane motion. This instability occurs when the helicopter is on the ground and is important for soft-inplane rotors where the rotating lag mode frequency is less than the rotor rotational speed. For the analysis, the bearingless rotor was composed of blades, flexbeam, torque tube, damper, shear restrainer, and pitch links. The fuselage was modeled as a mass-damper-spring system having natural frequencies in roll and pitch motions. The rotor-fuselage coupling equations are derived in non-rotating frame to consider the rotor and fuselage equations in the same frame. The ground resonance instabilities for three cases where are without lead-lag damper and fuselage damping, with lead-lag damper and without fuselage damping, and finally with lead-lag damper and fuselage damping. There is no ground resonance instability in the only rotor-fuselage configuration with lead-lag damper and fuselage damping.

• Industrial Engineering and Management Systems
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• v.3 no.2
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• pp.92-99
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• 2004

We consider the ATM switching node location problem (ANLP). In this problem, there are two kinds of facilities, hub facilities and remote facilities, with different capacities and installation costs. We are given a set of customers with each demand requirements, a set of candidate installation sites of facilities, and connection costs between facilities. We need to determine the locations to place facilities, the number of facilities for each selected location, the set of customers who are connected to each installed hub via installed remote facilities with minimum cost, while satisfying demand requirements of each customer. We formulate this problem as a general integer programming problem and solve it to optimality. In this paper, we present a preprocessing procedure to tighten the formulation and develop a branch-and-price algorithm. In the algorithm, we consider the integer knapsack problem as the column generation problem. Computational experiments show that the algorithm gives optimal solutions in a reasonable time.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.1
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• pp.37-46
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• 1999

The influence of the tip clearance upon the cavitation inception were investigated by experiments for ducted rotors having different tip clearances The axial and tangential mean velocities around the ducted rotors were measured using an L.D.V. system to investigate the correlation between tip vertex cavitation inception and hub vortex cavitation. Observation results for tip vortex cavitation and hub vortex cavitation show good agreement in trend with the analysis results of velocity measurement. An optimum tip clearance for ducted rotor was selected to delay the tip vortex cavitation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.285-287
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• 2014

Equations of motion for the vibration analysis of rotating pre-twisted beams with functionally graded material properties are derived in this paper. Based on Timoshenko beam theory, the effects of shear and rotary inertia are considered. The pre-twisted beam has a rectangular cross-section and is mounted on a rotating rigid hub with a setting angle. Functionally graded material (FGM) properties are considered along the height direction of the beam. The equations of stretching and bending motion are derived by Kane's method employing hybrid deformation variables. To validate the derived equations, natural frequencies of a rotating FGM pre-twisted beam are compared to those obtained by a commercial software ANSYS. The effects of the pre-twisted angle, slenderness ratio, hub radius, volume fraction exponent, and angular speed on the modal characteristics of the system are investigated with the proposed model.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.39-47
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• 2006

Recent trend in pursuit of high performance and effectiveness for automotive cooling system has changed the application of material for impeller of automotive water pump from metal to high ability engineering resin, which can achieve optimization of design of impeller geometry and realize lightweight high efficiency water pump. Closed type water pump improves hydraulic loss of fluid through the clearance between volute casing and impeller compared with that of the existing open type water pump(Although closed type is heavier than open type for the same size and same material, adoption of plastics can solve the problem.). In the present study, the characteristics of hydraulic performance of closed type water pump were investigated with respect to the angle between shroud and hub of impeller and the shape of discharge port of volute casing. Performance tests were carried out for 4 cases, that is, for 2 impellers and 2 casings. The modification of shape of only discharge port can enhance the hydraulic performance by 10 percent and the pump efficiency by 4-6 percent.

• Journal of Korean Port Research
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• v.7 no.1
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• pp.13-24
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• 1993

The rapid progress of the intermodal freight transportation in recent years has induced fierce competition among the adjacent hub ports for container transport. This brings increased attention to the evaluation of the port competitive ability. But it is not easy to evaluate the port competitive ability because this belongs to ill-defined system which is composed of ambiguous interacting attributes. Paying attention to this point, this paper deals the competitive ability of container port in Far-East Asia by fuzzy integral evaluation which is adequate to interacting ambiguous attribute problem. For this, the proposed fuzzy evaluation algorithm is applied to the real problem, based on the factors such as cargo volumes, costs, services, infrastructure and geographical sites These are extracted from the precedent study of port competitive ability, etc. The results show that the port evaluation factors come in following order ; services, costs, infrastructure, geographical sites and cargo volumes. There are some interactions(interaction coefficient, ${\lambda}=-0.664$ between evaluation attributes. The port competitive ability comes in following order : Singapore, Hongkong, Kobe, Kaoshiung and Busan. According to the sensitivity analysis, the rank between Busan and Kaoshiung changes when ${\lambda}=0.7$. From the analysis of the results, we confirmed that the proposed fuzzy evaluation algorithm is very effective in the complex-fuzzy problem which is composed of hierarchical structure with interacting attributes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.913-914
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• 2016

This paper analyzes the impact of the satellite TWTA non-linearity charateristics for shared band transmission technology to improve spectral efficiency in satellite communication system. In shared band transmission technology for star network, a hub and terminals use same frequency band. In order to receive terminals's signal a hub have to remove the its own DVB-S2 carrier. In this paper the non-linearity impact of satellite TWTA is analyzed for self-interference cancellation.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.397-400
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• 2024

2013년 도커가 등장한 이후, 컨테이너 기술을 기반으로 한 프로젝트 및 사업이 지속적으로 활성화되고 있는 추세이다. 도커 컨테이너는 커널을 포함하고 있지 않음에 따라 기존 가상머신에 비해 경량화된 형태로 애플리케이션을 프로비저닝하는데 활용될 수 있다. 또한, 도커에서는 퍼블릭 도커 이미지 레포지토리인 Docker Hub를 통해 개발된 도커 이미지가 공유 및 배포될 수 있도록 하여 개발자들이 자신의 목적에 부합하는 서비스를 구축하는데 많은 도움을 주고 있다. 최근에는 클라우드 네이티브 환경에 대한 수요가 증가하면서 컨테이너 기술이 더욱 각광받고 있는 실정이다. 이에 따라 도커 이미지 및 이를 기반으로 한 도커 컨테이너 환경에 대한 보안을 위한 연구/개발은 다수 이루어지고 있으나, 도커 이미지 라이선스 컴플라이언스 이슈에 대한 논의 및 민감 데이터 보호 방안에 대한 연구/개발은 부재한 상황이다. 이에 본 논문에서는 도커 이미지 라이선스 컴플라이언스 위반 방지 시스템을 제안하여 도커 이미지 업로드시, Docker Hub 내 도커 이미지와 유사도 검사를 수행할 수 있는 방안을 제시하고자 하며, 도커 이미지 내 민감 데이터를 식별하고 이를 보안할 수 있는 방안에 대해 제시하여 신뢰할 수 있는 도커 컨테이너 공급망을 구축할 수 있음을 보인다.

• Journal of Korea Port Economic Association
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• v.32 no.2
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• pp.1-24
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• 2016

Northeast Asia is changing rapidly, including becoming an increasingly important part of the world economy. Various logistical systems and networks are being established in this area, including South and North Korea, China, Japan, Russia, and Mongolia. Thus, a new systematic logistical network and development strategy is required. The division of the Korean peninsula has for a long time made the region ineffective in terms of land logistics. South Korea's connection to Eurasia is blocked by North Korea, which means it is essentially treated as an island. Furthermore, South Korea does not have an efficient logistics system or effective vision and strategy. Northeast Asia has the potential to be one of the largest economic communities in the world, similar to the EU and North America. Thus, a united Korea can play an important role as the land bridge of Northeast Asia and the logistical hub of the region. This study reviews the logistical position, tasks, and problems of the Korean peninsula and suggests a desirable development strategy and vision. Specifically, after examining the conditions for a land logistical system, focusing on railways, this study proposes several future-oriented development strategies and tactics that will position the peninsula as a logistical hub in Northeast Asia. We anticipate that this study will serve as the basis for future research that will investigate the topics presented here in more detail.