• Proceedings of the Korea Inteligent Information System Society Conference
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• 2002.05a
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• pp.191-200
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• 2002

오늘날 발전을 거듭하고 있는 첨단 정보기술을 이용한 지능형 시뮬레이션/시뮬레이터의 표준으로 확고히 자리를 잡고 있는 HLA(High Level Architecture)는 시뮬레이션 소프트웨어의 재사용성과 상호운용성을 촉진시키기 위하여 미 국방성에 의해 개발되어 이제는 분산 시뮬레이션의 표준이라 할 수 있다. 이 논문에서는 지능정보 기술이 시뮬레이션/시뮬레이터 기술과 어떻게 연관되어 있으며, 어떻게 사용될 것인가에 대한 개념 연구와, 시뮬레이션/시뮬레이터모델 내에서 첨단 정보기술들이 무슨 역할을 하는지에 대한 방향을 도출하였다. 또한, HLA와 HLA의 가장 중요한 구성 요소중 하나인 RTI(Run Time Infrastructure)의 최신 버전과 RTI가 지원하는 서비스에 대해 고찰하였다. HLA 페더레이션 개발자들이 HLA 페더레이션 개발시 지침이 되는 여섯 단계의 페더레이션 개발 절차인 FEDEP(Federation Development and Execution Process) 모델을 따랐으며, RTI의 최신 버전(RTI-NG 1.3v4)을 사용하여 HLA를 따르는 지능정보형 시뮬레이션 프로그램의 프로토타입을 개발하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.2
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• pp.233-240
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• 2019

High-altitude ElectroMagnetic Pulse(HEMP) is a high-power electromagnetic pulse caused by nuclear explosions at altitudes above 30 km. This pulse can cause serious damage to the electrical/electronic device. Therefore, there are a lot of studies on the effects of HEMP in the literature. When conducting studies on the effects of HEMP, it is essential to measure the simulated HEMP. Depending on the need for measurement, this paper focuses on the HEMP measurement method. This paper proposes a measurement method using frequency domain compensation to extract the correct waveform and solves the offset problem more efficiently than the conventional methods. The proposed method is verified by experiment using HEMP simulator and measurement system in ADD.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.34.3-34.3
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• 2008

Relative navigation system is presented using measurements from a single-channel global positioning system (GPS) simulator. The objective of this study is to provide real-time relative navigation results as well as absolute navigation results for two formation flying satellites separated about 1km in low earth orbit. To improve the performance, more accurate dynamic model and modified relative measurement model are developed. This modified method prevents non-linearity of the measurement model from degrading precision by applying linearization about the states from absolute navigation algorithm not about a priori states. Furthermore, absolute states are obtained using ion-free GRAPHIC pseudo-ranges and precise relative states are provided using double differential carrier-phase data based on Extended Kalman Filter. The software-based simulation is performed and achieved meter-level precision for absolute navigation and millimeter-level precision for relative navigation. The absolute and relative accuracies at steady state are about 0.77m and 4mm respectively (3D, r.m.s.). In addition, Integer ambiguity algorithm (LAMBDA method) improves simulation performances.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.201-208
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• 2005

To guarantee the quality of service for user request, we should consider various kinds of things. The important thing of QoS is that response time of service is transparently suggested 'to network users. We can know the response time of service using the information of network latency, system latency, and software component latency, In this paper, we carried out the modeling of network latency and analyzed the effects of packets loss to the network latency, Also, we showed the effectiveness of modeling using the NS-2. This research can help to provide the effective methods in case of SLA(Service Level Agreement) agreement between service provider and user.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.12
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• pp.704-715
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• 2004

Recently, a single or multi processor system uses the hierarchical memory structure to reduce the time gap between processor clock rate and memory access time. A cache memory system includes especially two or three levels of caches to reduce this time gap. Moreover, one of the most important things In the hierarchical memory system is the hit rate in level 1 cache, because level 1 cache interfaces directly with the processor. Therefore, the high hit rate in level 1 cache is critical for system performance. A victim cache, another high level cache, is also important to assist level 1 cache by reducing the conflict miss in high level cache. In this paper, we propose the advanced high level cache management scheme based on the processor reuse information. This technique is a kind of cache replacement policy which uses the frequency of processor's memory accesses and makes the higher frequency address of the cache location reside longer in cache than the lower one. With this scheme, we simulate our policy using Augmint, the event-driven simulator, and analyze the simulation results. The simulation results show that the modified processor reuse information scheme(LIVMR) outperforms the level 1 with the simple victim cache(LIV), 6.7% in maximum and 0.5% in average, and performance benefits become larger as the number of processors increases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.689-692
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• 2008

Noises from ceiling mounted air-conditioning units were recorded in various actual situations such as offices, classrooms and libraries. Eight specimens of air-conditioners from major domestic and foreign manufacturers' were investigated in this study. A head and torso simulator was located 1.5 m beneath the air-conditioner panel for the measurements and sound pressure levels of the recording sounds were varied from 28 to 55 dBA with 3 dB steps for subjective evaluations. A total of 88 stimuli was randomly presented to subjects using a headphone system in semi-anechoic chamber. Two-categorized (noisiness and amenity) nine-point scale was used as evaluation method. The third scale ('point 3') among the nine-point scale was set as the threshold of allowable level of the air-conditioning sounds in consideration of the real situations. The results indicate that the allowable sound pressure level is around 34 dBA for both noisiness and amenity categories.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1217-1222
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• 2004

This paper describes the development of tele-robotic interface for the hot-line maintenance robot system. One of main issues in designing human-robot interface for the hot-line maintenance robot system is to plan the control procedure for each part of the robotic system. Another issue is that the actual degree of freedom (DOF) in the hot-line maintenance robot system is much greater than that of available control devices such as joysticks and gloves in the remote-cabin. For this purpose, a virtual simulator, which includes the virtual hot-line maintenance robot system and the environment, is developed in the 3D environment using CAD data. It is assumed that the control operation is done in the remote cabin and the overall work process is observed using the main-camera with 2 DOFs. For the input device, two joysticks, one pedal, two data gloves, and a Head Mounted Display (HMD) with tracker sensor were used. The interface is developed for each control mode. Designed human-interface system is operated using high-level control commands which are intuitive and easy to understand without any special training.

• Journal of the Ergonomics Society of Korea
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• v.17 no.1
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• pp.23-36
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• 1998

The primary objective of this research was to establish and quantify the relationship between the physical degradation factors of multimedia telecommunications (teleconferencing) system and Subjective human perception. The research was performed in two stages. A field survey of the real users and pilot experiments were carried out in the first stage to determine customers' major complaints and corresponding system degradation factors. A prototype teleconferencing simulator was developed in two separate sound-treated chambers equipped with audio/video equipment running under a custom-developed software program. In the second stage, simulation experiments using the semantic differential methodology were performed utilizing 26 paid participants (14 college students and 12 housewives). The results indicated that audio/video synchronization and the frame rate were the main system factors for both subject groups, but different pattern of factors' influence was found according to the group, implying that the system configuration would hopefully accommodate the characteristics of the end users. Also, a single quality index, developed for system preference, was revealed to be highly correlated with user satisfaction. The results provide some fundamental data on the human subjective perception of multimedia telecommunications quality, and further can help establish the quality standards to enhance service level.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.232-238
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• 2013

In this paper we describe the maximum energy transfer of CSA(Capacitive Switching Antenna). CSA which is radiated antenna system contain energy storage and switch, antenna needs to high voltage source for electrical field radiation experiment. In this experiment we employed Marx generator as a charging source. CSA can radiate electrical field more efficiently by varying antenna capacitance. The electromagnetic generation system which was using CSA has some advantages which are more simple and more effective compared to exist system. We evaluated the performance of electromagnetic wave generating system using CSA. As a result UWB gain of system is 0.47, It is higher level than exist system is 0.3. Radiated electrical field strength at 1m is 70kV/m. It is measured by D-dot sensor and gap distance is 20mm. Center frequency of CSA is approximately 25MHz. When vary the antenna gap distance from 50mm to 20mm, we can find the radiation field strength is decrease and antenna center frequency is increased. We also simulated the energy transfer efficiency to compare with experiment result. Consequentially, CSA needs to appropriate capacitance which is similar value from marx generator for maximum energy transfer, and gap is less than 1mm to increase the CSA capacitance.

• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.54-59
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• 2023

In this paper, we analyze experimental results by applying the PHILS model to a lab-scale superconducting current limiter system for its actual application in medium-voltage direct current (MVDC) systems. Superconducting current limiters exhibit effective current-limiting performance in circuit breaker operations, particularly in limiting large fault currents within a short period, addressing the challenges posed by the increasing use of renewable energy and the integration of DC medium-voltage distribution systems. The development of such superconducting current limiters faces various technical and cost disadvantages, especially when applying a medium-voltage 35kV level system, which is intended for future introduction. The proven lab-scale superconducting current limiter system and the PHILS model are combined and integrated into the actual system. Our plan involves analyzing the limiter's performance, assessing its impact on the system, and preparing for its application in future medium-voltage systems. Utilizing RTDS, a simulation was conducted by connecting actual scaled-down equipment and systems, with the analysis results presented.