• 한국군사과학기술학회지
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• 제13권3호
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• pp.413-420
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• 2010

An Estimation of VHF data link range for EW(Electronic Warfare) equipment in the sea environment was studied to predict the data link range between transmitting and receiving station. The theoretical estimation predicts within 3% error with actual measurement of VHF data link range at sea. Data link range factors including refraction and reflection are added in the basic wave propagation equation. The effect of refraction and reflection to the range is analysed with quantity level.

• 반도체디스플레이기술학회지
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• 제19권1호
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• pp.42-48
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• 2020

As global warming accelerates, eco-friendly electric cars are being developed to reduce carbon dioxide emissions, and power conversion inverters are used to drive motors. Among inverter components, DC-link capacitor is heated by high current usage, which causes problems such as performance and life-saving of inverter. Although metal cases with good thermal performance have been used to solve this problem, it is difficult to apply them in practice due to insulation problems with other parts. In this paper, the Heat-Generation influence factor of DC-link capacitor is analyzed. Variables on heat-generation are set at 3 levels for film width, inductance, and film thickness. Box-Behnken to 13 tests using the design and minimal deviations, e.g. through the experiment three times by each level. The surface of the film k type by attaching the sensor current is measured temperature. Capacitance was set to a minimum level of 200 ㎌ and had a frequency of 16 kHz with Worst case, ambient temperature of 85℃ and a ripple current of 50 Ams was applied. The temperature at the measurement point was collected in the data logger after sampling at 1 minute intervals for 2 hours after saturation with the ambient temperature. This experiment confirmed that setup factors are correlated with heat-generation.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.89-92
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• 1996

It is generally recognized that Video On Demand (VOD) service will become a promising interactive service in B-ISDN. We consider a hierarchical two level network architecture for VOD service. The first level consists of connected Local Video Servers(LVSs) in which a limited number of high vision programs are stored. The second level has one Central Video Server(CVS) containing all the programs served in the network. The purpose of this paper is to analyze the network traffic and to propose the storage policy for LVSs. For this purpose, we present an analysis of program storage amount in each LVS, transmission traffic volume between LVSs, and link traffic volume between CVS and LVSs, according to changing the related factors such as demand, the number of LVSs is also presented on the basis of the tradeoffs among program storage cost, link traffic cost, and transmission cost.

• 한국직업건강간호학회지
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• 제23권2호
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• pp.97-105
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• 2014

Purpose: The purpose of this study was to identify the link between health-related physical fitness level and cardiovascular disease-related risk factors in adult male workers. Methods: We tested cardiovascular disease-related risk factors (waist circumference, SBP, DPB, fasting glucose, TC, HDL-C, TG, LDL-C) and health-related physical fitness ($VO_2max$, grip, Sit-up, Flexibility, Body fat) and divided health-related physical fitness level of the subjects into 3 groups - A (very good, n=56), B (good, n=59), and C (below-average, n=57) according to the criterion of the Health and Fitness counseling guidelines of KOSHA. The statistical techniques such as standard deviation, one-way ANOVA and multiple regression (p<.05) were used. Results: There were significant differences between group C and group B & A (p<.001) in waist circumference, DBP, Fasting glucose, HDL-C, TG, LDL-C. In TC/HDL-C, TG/HDL-C, LDL-C/HDL-C, Group C was higher than group B and A. Conclusion: On the basis of these results, we identified that improvement of health-related physical fitness level positively effects on the decrease of cardiovascular disease-related risk factors.

• 국토계획
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• 제54권4호
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• pp.26-37
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• 2019

It is necessary to implement a wide range of housing welfare policies that citizens can experience in order to improve residents' the quality of life, as it emphasizes the balance of supply and management of public housing. The purpose of this study is to analyze the factors affecting residential satisfaction considering the three hierarchical levels of individual, household, and area. In the background of the study, the individuals' quality-of-life satisfaction determined not only by the individual but also by the various influencing environmental factors. This study targets 1,736 households, 3,239 persons in 464 areas in Seoul. The main research results are as follows. At the level one, there were influencing factors such as age(-), education level and income, and housing area per person, recipient of basic living(-), period(-) and RIR (at the level two). At the level three, west-south region(-) and social mix affect the complex of public housing. In consideration of living infrastructure, the closer to public transportation, public facilities, and medical facilities, the higher the satisfaction of public housing. The results of this analysis suggest that public support needs to focus on individual household members, but there is a need for ways to link it with the complex and the region.

• Journal of Communications and Networks
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• 제8권2호
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• pp.241-252
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• 2006

Traditional service-level agreements (SLAs), defined by average delay or packet loss, often camouflage the instantaneous performance perceived by end-users. We define a set of metrics for service availability to quantify the performance of Internet protocol (IP) backbone networks and capture the impact of routing dynamics on packet forwarding. Given a network topology and its link weights, we propose a novel technique to compute the associated service availability by taking into account transient routing dynamics and operational conditions, such as border gateway protocol (BGP) table size and traffic distributions. Even though there are numerous models for characterizing topologies, none of them provide insights on the expected performance perceived by end customers. Our simulations show that the amount of service disruption experienced by similar networks (i.e., with similar intrinsic properties such as average out-degree or network diameter) could be significantly different, making it imperative to use new metrics for characterizing networks. In the second part of the paper, we derive goodness factors based on service availability viewed from three perspectives: Ingress node (from one node to many destinations), link (traffic traversing a link), and network-wide (across all source-destination pairs). We show how goodness factors can be used in various applications and describe our numerical results.

• 대한방사선기술학회지:방사선기술과학
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• 제46권5호
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• pp.435-444
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• 2023

The purpose of this study was to analyze the factors that demographic factors, radiation knowledge level, and radiation awareness could be affecting the benefits of radiation. From July 2022 to July 2023, after receiving consent to participate by using the link of Naver through Social Network Service (SNS) for the general public, 312 people were surveyed by self-registration method without collecting personal information. The questionnaire consisted of a total of 25 questions following demographic factors (5 questions including age group by life cycle, sex, monthly household income, residence), radiation knowledge level (8 questions including basic physical, biological effects, radiation protection technology), radiation awareness (12 questions including risk, management, benefit). Independent sample T-test and ANOVA tests were performed for significant differences in the average radiation awareness between variables, and hierarchical regression was performed to identify influencing factors on radiation benefits. As a result, the benefit of radiation was significantly high among the radiation awareness, but the awareness of the danger of radiation was insufficient to the level of recognizing it as safe. Men had significantly higher awareness of radiation management and benefits than women, and the awareness of radiation management was significantly higher in the middle class with a monthly household income of 4.31 million won or more. The higher the knowledge level of radiation, the higher the awareness of the benefits of radiation. The factors that had a positive effect on radiation benefits were the high level of radiation knowledge and awareness of radiation management.

• 대한전자공학회논문지SD
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• 제46권10호
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• pp.79-85
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• 2009

본 논문은 $0.18{\mu}m$ CMOS 공정을 이용하여 3.2 Gb/s serial link receiver를 설계하였다. High-speed links의 performance를 제한하는 가장 큰 요소는 transmission channel bandwidth, timing uncertainty가 있다. 이러한 문제점을 해결하기 위한 방법으로 multi-level signaling(4-PAM)을 이용하였다. 추가적으로 전송속도를 높이고 BER를 낮추기 위한 방법으로 current-mode amplifier, CML sampling latch를 사용하였다. 4-PAM receiver의 최대 데이터 전송속도는 3.2 Gb/s이다. BER은 $1.0{\times}10^{-12}$ 이하이며 chip size는 $0.5\;{\times}\;0.6\;mm^2$이고 1.8 V supply voltage에서 49mA current를 소모한다.

• 한국군사과학기술학회지
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• 제12권3호
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• pp.259-265
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• 2009

In the traditional percussion locks of small arms, a firing pin is struck by a hammer rotating on a single center of rotation, which makes the percussion mechanism simple and reliable. In order to strike the firing pin by the hammer, however, the firing pin should be located within the radius of rotation of the hammer. As the distance between the striking point of the firing pin and the center of rotation of the hammer becomes longer, the radius of rotation of the hammer should also be increased, which results in the increase of the volume and weight of the small arms because the hammer needs the more space for its operation inside of the small arms. In this paper, a link type percussion lock was newly proposed in order to overcome the limitation of designing small arms when using traditional percussion locks, as mentioned above. The link type percussion lock was modeled by using multi-body dynamics software and designed to satisfy the requirements such as striking force level of the hammer exerting on the firing pin enough to detonate the percussion cap of ammunitions and the safety on the accidental drop. It was applied to the newly developed dual-barrel weapon system, in which the weight and overall length are important design factors, and verified by durability test and drop test on the ground.

• Journal of Power Electronics
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• 제17권6호
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• pp.1500-1511
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• 2017

The purpose of this paper is to study a high-performance control scheme for neutral-point-clamping three-level (NPC-3L) inverter fed dual three-phase permanent magnet synchronous motor (PMSM) drives by considering some asymmetric factors such as the non-identical parameters in phase windings. To implement this, the system model is analyzed for dual three-phase PMSM drives with asymmetric factors based on the vector space decomposition (VSD) principle. Based on the equivalent circuits, PI controllers with feedforward compensation are used in the d-q subspace for regulating torque, where the cut-off frequency of the PI controllers are set at the twice the fundamental frequency for compensating both the additional DC component and the second order component caused by asymmetry. Meanwhile, proportional resonant (PR) controllers are proposed in the x-y subspace for suppressing the possible unbalanced currents in the phase windings. A dual three-phase space vector modulation (DT-SVM) is designed for the drive, and the balancing factor is designed based on the numerical fitting surface for balancing the DC link capacitor voltages. Experimental results are given to demonstrate the validity of the theoretical analysis and the proposed control scheme.