• 한국컴퓨터정보학회논문지
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• 제27권6호
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• pp.117-122
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• 2022

본 논문에서는 IoT와 저 전력 장거리 통신(NB-IoT)기술을 적용한 차량관제용 단말기를 개발했다. 본 시스템은 주차중인 차량의 위치, 상태에 대한 정보를 수집하고, 저 전력 실시간으로 차량 소유자의 단말로 차량 상태를 전송하여 차량의 도난을 방지하고, 주행 중인 차량의 경우, 주행 속도, 급제동, 미끄러짐, 충격 등 차량의 1차 정보를 수집하여 서버로 전송하면 서버에서 관련 데이터를 분석하여 교통 정체, 도로 파손 안전사고 발생 등에 대한 2차 정보를 생성할 수 있으며, 주기적 알람 형태로 목적지의 예상 도착 시간을 전송하여 목적지에 차량의 정확한 도착 시간을 알 수 있다. 본 단말 장치는 차량용 IoT 게이트웨이로 차량 내부의 다양한 유무선 센서와 연결될 수 있다. 또한 자동차의 유지관리, 효율적인 운행과 차량들에게서 수집된 데이터를 민간 또는 공공부분에서 유용하게 활용할 수 있다.

• 정보교육학회논문지
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• 제8권1호
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• pp.91-99
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• 2004

유비쿼터스 환경이 도래함에 따라 언제 어디서나 어떤 단말기를 통해서도 정보를 얻을 수 있는 환경이 제시되었고, 모바일 장비의 성능이 개선되어가면서 무선인터넷 환경을 기반으로 운영될 수 있는 솔루션의 수요가 점차 증가되고 있는 추세이다. 이에 본 논문에서는 무선인터넷 환경에 적응력 있게 대응하기 위한 원격 교육 솔루션을 개발하고자 하며 이를 위하여 다른 그래픽 포맷들과는 달리 해상도의 크기가 변경되더라도 고품질의 가독성을 유지할 수 있는 SWF를 이용하여 포켓 PC의 대역폭 및 해상도 문제를 해결한 원격교육시스템을 설계 및 구현하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.333-335
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• 2001

In this paper, an algorithm for fault location in Auto Transformer(AT) Feeding Railway system is presented. If a fault occurs at the AT feeding circuits of electrical railway system, it is very important to find fault location and to remove it immediately for the purpose of ensuring safety for transportation. Because the characteristics of reactance-distance are not linear, only using one terminal signals to give fault distance is difficult. In this paper, first, using the KVL, 4 voltage equation are obtained. Secondly, eliminating voltage a distance equation which consists of currents at rail and line parameters including mutual effects.

• 조명전기설비학회논문지
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• 제27권7호
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• pp.89-94
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• 2013

This paper presents a method of simulating the protection effects of surge protective devices(SPDs) depending on the protective distance and types of input impedance of load to be protected. In order to analyze the protective performances of voltage-limiting type SPDs associated with the reflection and oscillation phenomena, the terminal voltage across load being protected and the residual voltage of SPDs were simulated by using EMTP model as functions of the protective distance and types of input impedance of loads. As a consequence, SPDs should be installed by taking into account the protective distance and input impedance of loads to achieve reliable protection of electrical and electronic equipment from lightning and switching surges. It is expected that the simulation method proposed in this paper could be practically used in design for installing SPDs in low-voltage distribution systems.

• 한국간호교육학회지
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• 제29권1호
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• pp.60-71
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• 2023

Purpose: The purpose of this study was to identify changes in the experience rate and level of symptoms of visual display terminal syndrome in college students attending online classes during the COVID-19 pandemic. Methods: Data were collected from February 22 to June 8, 2021 at three measurement points. A total of 117 college students were administered a visual display terminal syndrome survey just before online classes (T1), one month after the start of online classes (T2), and three months after the start of online classes (T3). The collected data were analyzed by frequency and percentage, paired t-test, McNemar test, and repeated measures analysis of variance using the IBM SPSS 25.0 program. Results: The intensity of college students' visual display terminal syndrome during online classes increased at T2 and T3 compared to T1. The rate of experiencing back discomfort or pain increased abruptly at T2 compared to T1. The intensity of college students' eye related symptoms and skin related symptoms increased at T2 and T3 compared to T1, while the intensity of college students' psychological symptoms, general body discomfort, and musculoskeletal symptoms increased at T3 compared to T1. Conclusion: The results of this study suggest that self-care programs are needed to prevent visual display terminal syndrome in college students who are in long-term online classes.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.719-728
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• 2017

This paper proposes a synthesis of new guidance law to generate an evasive maneuver against enemy's missile interception while considering its impact angle, acceleration, and field-of-view constraints. The first component of the synthesis is a new function of repulsive Artificial Potential Field to generate the evasive maneuver as a real-time dynamic obstacle avoidance. The terminal impact angle and terminal acceleration constraints compliance are based on Time-to-Go Polynomial Guidance as the second component. The last component is the Logarithmic Barrier Function to satisfy the field-of-view limitation constraint by compensating the excessive total acceleration command. These three components are synthesized into a new guidance law, which involves three design parameter gains. Parameter study and numerical simulations are delivered to demonstrate the performance of the proposed repulsive function and guidance law. Finally, the guidance law simulations effectively achieve the zero terminal miss distance, while satisfying an evasive maneuver against intercept missile, considering impact angle, acceleration, and field-of-view limitation constraints simultaneously.

• 한국간호교육학회지
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• 제22권4호
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• pp.485-494
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• 2016

Purpose: The present research is a descriptive study aimed at understanding clinical nurses' Video display terminal (VDT) syndrome and identifying the factors that affect their VDT syndrome. Methods: Data were collected from 239 clinical nurses working in two metropolitan cities. Research tools included subject's VDT syndrome assessing musculoskeletal, ophthalmic, dermal, psychiatric, and whole body syndromes. The data were analyzed using frequency analysis, average and standard deviation, t-test, One-way ANOVA, and multiple regression analysis with the SPSS/WIN 20.0 program. Results: The subjects' VDT syndrome score was 1.34 out of 5. There were significant differences in participating subjects' VDT syndrome, hospital's size, working unit, health status, diagnosis of illness, having an Order Communication System (OCS), having an Electronic Medical Record (EMR) System, continuous VDT working for more than one hour, break time during VDT use, VDT use time, comfort of the chair, adjustability of the height of the chair, size of the VDT's desk, distance between the monitor and the user's eyes, resolution of the monitor, and frequency of eye exercise during VDT use. According to the research, influencing factors on VDT syndrome in clinical nurses included size of the VDT's desk, frequency of eye exercise during VDT use, having an EMR system, break time during VDT use, diagnosis illness, and having an OCS' system. Conclusion: The findings from this study can be used as a basis for future VDT syndrome prevention education and programs for clinical nurses.

• 한국인터넷방송통신학회논문지
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• 제14권3호
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• pp.51-56
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• 2014

TETRA(TErrestrial Trunked RAdio)는 디지털 TRS(Trunked Radio System)의 유럽 표준으로 재난통신에 특화된 서비스를 제공한다. 특히 TETRA에서 제공하는 DMO(Direct Mode Operation) 기능은 기지국 중계 없이 단말기간 직접통신이 가능하여 기지국 전파가 도달되지 않는 음영지역에 효과적으로 활용된다. 하지만 사용자들이 DMO기능을 보다 효과적으로 활용하기 위해서는 전파도달범위 예측 정보가 제공되어야 한다. 따라서 본 논문에서는 국내에 보급되어 운용 중인 TETRA DMO 단말기의 링크버짓을 계산하고 이를 경로손실 모델에 적용시켜 지역 환경별 전파도달 거리를 예측하였다.

• 한국군사과학기술학회지
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• 제2권2호
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• pp.117-130
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• 1999

In this paper, the performance of data communication function of military radio equipment P-999K is analyzed based on the standard CSMA/CA protocol which is DFWMAC standard protocol done by IEEE802.11 work group. Basic three standard protocols, i.e. Basic CSMA/CA, Stop & Wait ARQ and 4-Way Handshake CSMA/CA protocols are analyzed and compared with each other under the hidden terminal environment. The computer simulation is also done by using SIMSCRIPT II.5 which is popular software tool for an independent processing. The results show that p-persistent(with p=0.3) CSMA scheme is superior to non-persistent CSMA scheme with non-hidden terminal condition, but the performances of both schemes are almost same with hidden terminal situation. And the results of computer simulations are also showed that Basic CSMA/CA protocol is superior to the other protocols when the ratio of hidden terminals is below 10 % of total user population, however, with the above 20% hidden terminals environment and the higher offered traffic conditions the 4-Way Handshake CSMA/CA protocol shows the most superior performance.

• 한국군사과학기술학회지
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• 제27권2호
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• pp.238-246
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• 2024

Modern military operations rely heavily on broadband communication and data transmission. Recently, the rising use of intelligent unmanned technology necessitates more frequencies. Free-space optical(FSO) communication can offer high-data-rate communications with high security and no need for licensing. Therefore, the FSO communication holds significant interest and potential in the defense industry. In this paper, we present design of a FSO communication terminal taking Korean domestic weather conditions into account. The domestic atmospheric attenuation is analyzed using several models and two-year meteorological information for a city in Korea, and this analysis is utilized to design the FSO communication terminal. The design results were verified using an FSO communication test bed, and we achieved an Ethernet bandwidth of approximately 1.86 Gbps at a distance of 1.3 km with the optical amplifier output power of the test bed set to about 20 dBm.