• 전기학회논문지P
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• 제67권3호
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• pp.155-159
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• 2018

Recently, the expansion or establishment of facilities for the logistics system is increasing. Conveyor facilities play a major role in sorting and transporting logistics. Induction motors are widely used for the operation of these conveyor systems. In the logistics system, a large number of induction motors are used. These motors have a considerable distance from the power source side and have a low power factor. The installation position for the power factor compensation of the induction motor is very important. Since the voltage drop depends on the length of the line, it is an important parameter in capacitor capacity determination for power factor compensation. The capacity of the capacitors installed to compensate the power factor of the inductive load should be designed to the extent that self-excitation does not occur. In this study, we analyze the method of compensating the proper power factor considering the voltage drop and the installation position of the induction motor in the logistics system.

• 한국컴퓨터정보학회논문지
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• 제8권3호
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• pp.144-149
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• 2003

멀티미디어 데이터는 실시간 제약을 갖고 있기 때문에 암호화/복호화로 인한 지연이 실시간 제약에 미치는 영향을 최소로 하면서 암호화를 하기 위해서는 네트워크 트래픽과 부하에 적응하여 암호화 알고리즘을 변경하기 위한 방법이 필요하다. 또한 다수가 참여하는 멀티미디어 서비스 진행 중에 서비스 이용을 중지한 사용자는 RTP payload의 암호화 키를 알고 있기 때문에 이 사용자로부터 RTP payload를 보호하기 위해서는 암호화 키를 변경하기 위한 방법이 필요하다. 따라서 본 논문에서는 RTP payload의 암호화를 위해 암호화 알고리즘과 암호화 키를 변경하기 위한 RPT 보안제어 프로토콜을 설계하고 구현하였다.

• 융합보안논문지
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• 제2권1호
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• pp.49-57
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• 2002

멀티미디어 정보 전송을 위해 RTP(Real-Time Transport Protocol)을 사용하며, 멀티미디어 정보 보안을 위해서는 RPT의 페이로드를 암호화해야 한다. RPT 페이로드의 암호화를 위해서 암호화/복호화로 인한 지연이 멀티미디어 정보의 실시간 제약에 미치는 영향을 최소로 하면서 네트워크의 트래픽과 부하에 적응하며 암호화 알고리즘을 변경하기 위한 방법이 필요하다. 또한 멀티미디어 서비스 진행 중 서비스 이용을 중지한 사용자는 RPT 페이로드의 암호화 키를 알고 있기 때문에 페이로드를 보호하기 위해서는 암호화 키를 변경하기 위한 방법이 필요하다. 따라서 본 논문에서는 RPT 페이로드의 암호화를 위해, 암호화 알고리즘과 암호화 키를 변경하기 위한 SCPR(Security Control Protocol for RTP)를 설계하고 구현하였다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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• pp.397-402
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• 1998

PID controller has been used very widely in the industrial applications. But it is difficult tune the PID gains. In this paper, we present a design of optimal 2-DOF PID controller for control of container crane which has to control swing motion and trolley position. For tuning of the 2-DOF PID control gains, we used hybrid evolution program(EP). During operate the crane system in yard, the goal is transporting the load to a goal position as quick as possible without rope oscillation. The crane is generally operated by an expert operator, but recently an automatic control system with high accuracy and rapid transportation is required. However, we developed an optimal controller which has to control the crane system with disturbance.

• 한국구조물진단유지관리공학회 논문집
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• 제19권2호
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• pp.143-150
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• 2015

현재 국내 모듈러 구조물은 저층의 단독주택 및 군 병영생활관에 한정되어 있는 실정이며, 적층식 모듈러 구조물에 대한 표준화된 구조설계 방법이 없으므로 구조물의 시공과정에서 모듈의 양중이나 운송 시 발생되는 관성력, 양중 시 구조물에 대한 풍하중의 영향, 모듈의 적층 설치 시 충격력 등에 대한 검토가 일반적으로 이루어지고 있지 않다. 따라서 본 연구에서는 대상 모듈러 시스템에 대한 단계별 시공방법을 살펴보고, 각 시공단계에 대한 구조해석 시 경계조건 및 하중 작용위치를 결정하였다. 또한 모듈의 양중 및 차량운반 시 각각의 속도에 따른 관성력을 산정하였으며 모듈의 적층설치 작업 시 양중속도에 따른 충격하중과 양중에 의한 설치작업 시 순간풍속에 의한 풍하중을 산정하였다. 제안된 방법을 토대로 대상 모듈러 시스템에서 양중 시와 운송 시, 설치 시 등 시공단계별 하중크기 결정조건을 변화시켜 구조검토를 수행하였으며 구조적으로 안전성이 확보되는 시공조건을 도출하였다.

• 설비공학논문집
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• 제16권2호
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• pp.142-149
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• 2004

Recently, the government introduced the thermal storage system for reducing the electric power load. Especially, the ice slurry type has gained lots of interest due to its good heat transfer and flowing characteristics. This study was peformed to understand the effects of transporting ice slurry through elbows of various angle. Propylene glycol water solution was used and about 2 mm ice particles were circulated. The experiments were carried out under various conditions, such as concentration and velocity of water solution ranging between 0∼20 wt％, 1.5∼2.5 m/s, respectively. And elbows with 4 different angles of 30$^{\circ}$, 45$^{\circ}$, 90$^{\circ}$, 180$^{\circ}$. The differential pressure and IPF (ice packing factor) between the pipe entry and exit were measured. The tendency of pressure loss and outlet IPF in elbow is that the pressure loss was reduced as concentration and flow velocity of water solution is increased, and low value appeared at 10 wt％ and 2.5 m/s. The variation of outlet IPF was compared with the inlet IPF in the range of $\pm$20％.

• 설비공학논문집
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• 제16권11호
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• pp.1028-1034
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• 2004

Recently, the ice storage system using ice slurry has been used increasingly since it has been introduced where the rapid cooling load change is required. Because it overcomes a decrease of the melting performance and an increase of the thermal resistance on the ice layer in static ice thermal storage system. This study is performed to understand the effects of transporting ice slurry through horizontal, vertical and inclined tubes ($30^{\circ},\;45^{\circ}$). It used propylene glycol-water solution and ice particles (diameter of about 2 mm) in this experiment. The experiments were carried out under various conditions, with concentration of water solution ranging from 0 to $20wt\%$, and velocity of water solution at the entry ranging from 1.5 to 2.5 m/s. The results were as follows: Regarding the angle of inclined tube, the highest pressure loss was measured for vertical tube and the pressure loss for $45^{\circ},\;30^{\circ}$, horizontal straight tubes were lower successively. The lowest pressure loss in these tubes was measured at velocity of $2.0{\sim}2.5m/s$ and concentration of $10wt\%$. The outlet IPF was likewise stable in these ranges.

• 로봇학회논문지
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• 제17권2호
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• pp.191-197
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• 2022

In this research, we developed the muscle-strength-assistant device, named as LEXO-W, and conducted suitability test for army when transporting high weights. LEXO-W relieves the burden when carrying heavy weights by distributing the load concentrated on the arms throughout the body. LEXO-W weighs 4 kg and is designed to handle objects weighing up to 55 kg. To verify the effectiveness of the device, object handling tests (high explosive shell, simple assembly bridges, and ammunition boxes) were conducted. Working time, metabolic rate, and electromyogram (EMG) signals were measured in each test. As a result, it was confirmed that the working time, metabolic rate and EMG signal before and after wearing LEXO-W were decreased. This research has great significance in that it verified the performance of the wearable device from the perspective of military operation.

• 로봇학회논문지
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• 제18권3호
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• pp.299-307
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• 2023

In the midst of accelerating wars around the world, unmanned robot technology that can guarantee the safety of human life is emerging. ERP-42 is a modular platform that can be used according to the application. In the field of defense, it can be used for transporting supplies, reconnaissance and surveillance, and medical evacuation in conflict areas. Due to the nature of the military environment, atypical environments are predominant, and in such environments, the platform's path followability is an important part of mission performance. This paper focuses on reducing the minimum turning radius in terms of improving path followability. The minimum turning radius of the existing 2WS/2WD in-wheel platform was reduced by increasing the torque of the independent driving in-wheel motor on the rear wheel to generate oversteer. To determine the degree of oversteer, two GPS were attached to the center of the front and rear wheelbases and measured. A closed-loop speed control method was used to maintain a constant rotational speed of each wheel despite changes in load or torque.

• 방사성폐기물학회지
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• 제21권4호
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• pp.503-516
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• 2023

A transfer cask serves as the container for transporting and handling canisters loaded with spent nuclear fuels from light water reactors. This study focuses on a cylindrical transfer cask, standing at 5,300 mm with an external diameter of 2,170 mm, featuring impact limiters on the top and bottom sides. The base of the cask body has an openable/closable lid for loading canisters with storage modules. The transfer cask houses a canister containing spent nuclear fuels from lightweight reactors, serving as the confinement boundary while the cask itself lacks the confinement structure. The objective of this study was to conduct a structural analysis evaluation of the transfer cask, currently under development in Korea, ensuring its safety. This evaluation encompasses analyses of loads under normal, off-normal, and accident conditions, adhering to NUREG-2215. Structural integrity was assessed by comparing combined results for each load against stress limits. The results confirm that the transfer cask meets stress limits across normal, off-normal, and accident conditions, establishing its structural safety.