• Journal of Positioning, Navigation, and Timing
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• 제6권3호
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• pp.87-94
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• 2017

GNSS modernization and development is in progress throughout the globe, and it is focused on the addition of a new navigation signal. Accordingly, for the next-generation GNSS signals that have been developed or are under development, various combinations that are different from the existing GNSS signal structures can be introduced. In this regard, to design an advanced signal, it is essential to clearly understand the effects of the signal structure and design variables. In the present study, the effects of the GNSS spreading code period and GNSS data bit duration (i.e., signal design variables) on the signal processing performance were analyzed when the data bit transition was considered, based on selected GNSS signal design scenarios. In addition, a method of utilizing the obtained result for the design of a new GNSS signal was investigated.

• 대한의용생체공학회:의공학회지
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• 제17권4호
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• pp.491-498
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• 1996

The development of a compact two-wavelength Nd:YAG laser for dental and ENT applications is presented. The Nd:YAG resonator generates either 1.06$\mu$m or 1.32$\mu$m. The wavelength selection is made at the control panel. The Nd:YAG laser parameters at 1.06$\mu$m are ; the maximum pulse duration of 150$\mu$s, repetition rates of I-100Hz, and the maximum average power of 25W. At 1.32$\mu$m, the pulse duration is the same where the repetition rates and the maximum average power are I-30Hz and lOW respectively. High voltage power supply consists of a simmer module and two identical high voltage DC converters. In order to make a complete medical laser system, an optical fiber delivery unit, foot pedal and water spray handpiece are also developed. The wavelength selection is reliable since no movement of optical or mechanical components is required. The high voltage power supply is compact, easy to be maintained and applicable for other laser systems due to its modular design.

• 대한교통학회지
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• 제28권6호
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• pp.85-97
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• 2010

본 연구는 정류소에서 여러노선의 버스가 동시에 몰려들어오는 버스몰림운행의 실태를 파악하고 이로 인해서 야기되는 문제점을 개선하기 위하여 버스몰림 운행지속시간 모형을 추정하고 버스몰림운행에 영향을 미치는 요인을 분석하였다. 버스몰림지속시간의 관측치를 대상으로 8개의 지속시간에 대한 분포를 검토하여 가장 적합도가 높게 나타난 weibull 분포를 가정한 모형을 개발하였다. 18개 영향변수를 검토하였으며 정차면수, 정차면수당 노선수, 노선당 최대 승하차인원을 설명변수로 하는 버스몰림운행 지속시간 모형을 개발하였다. 중앙버스전용차로(도봉미아로)와 가로변 전용 및 일반차로(통일의주로)에 대한 모형을 각각 도출하여 비교하였다. 그 결과, 도봉미아로의 몰림지속시간은 통일의주로에 비해 교통량에 대한 영향을 많이 받으며, 통일의주로는 도봉미아로에 비해 정차면수와 정차면수당 노선수, 노선당 최대 승하차인원에 많은 영향을 받는 것으로 나타났다. 개발된 모형을 토대로 버스몰림운행 현상의 완화방안을 제시하였다.

• 대기
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• 제23권3호
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• pp.275-282
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• 2013

In this study, the numerical model was developed to evaluate the observational environment of sunshine duration and, for evaluating the accuracy and utility of the model, it was verified against the observational data measured at Dae-gu Automated Synoptic Observing System (ASOS) located in an urban area. Three-dimensional topography and building configuration as the surface input data of the model were constructed using a Geographic Information System (GIS) data. First, the accuracy of the computing planetary positions suggested by Paul Schlyter was verified against the data provided by Korea Astronomy and Space Science Institute (KASI) and the results showed that the numerical model predicted the Sun's position (the solar azimuth and altitude angles) quite precisely. Then, this model was applied to reproduce the sunshine duration at the Dae-gu ASOS. The observed and calculated sunshine durations were similar to each other. However, the observed and calculated sunrise (sunset) times were delayed (curtailed), compared to those provided by KASI that considered just the ASOS's position information such as latitude, longitude, and elevation height but did not consider the building and topography information. Further investigation showed that this was caused by not only the topographic characteristic (higher in the east and lower in the west) but also the buildings located in the southeast near the sunrise and the southwest near the sunset. It was found that higher building resolution increased the accuracy of the model. It was concluded that, for the accurate evaluation of the sunshine duration, detailed building and topography information around the observing sites was required and the numerical model developed in this study was successful to predict and/or the sunshine duration of the ASOS located in an urban area.

• 한국해안·해양공학회논문집
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• 제24권5호
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• pp.319-325
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• 2012

조간대 저서생물들의 서식환경을 결정하는 중요한 인자 중의 하나인 노출시간을 추정하는 공식을 개발하였다. 이 공식은 기존의 1시간 간격, 1년 기간 조위자료를 이용하여 노출시간을 추정하는 방법과는 달리 대부분 연안의 기본 조석 정보에 해당하는 주요 4분조 조화상수들을 이용하여 노출시간을 간단하게 계산할 수 있다. 서해안의 관측 조위자료를 이용한 노출시간과 본 연구에서 개발한 공식에 의한 추정결과를 비교한 결과 RMS 오차는 0.8-1.4%로 파악되었다. 본 공식은 장기간의 조위자료가 없는 조간대 지역에서 간단하면서도 정확한 노출 시간 및 침수시간 추정에 활용할 수 있다.

• 한국항해항만학회지
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• 제41권2호
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• pp.39-46
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• 2017

This study represents a fundamental research for a passenger-ship escape guidance system that is a ship-borne agent, and it is for the support of escape decision-making by providing accurate maritime safety information in real time. We conducted a passenger escaping experiment on a training ship, SAEYUDAL, using the situation-aware escape guidance system, which has been developed for on-board application based on products for buildings. It is shown that the system contributes to the shortening of the escape duration and the dispersion of the escaping persons by generating and guiding the safe escape routes which dangerous areas are considered. From the experiment on ship's heeling condition, it is revealed that the heeling angle is linearly related to the escape duration. Therefore, this study shows that the shortening of the escape duration enables a safe and rapid mustering that is the most important process under emergency and appropriate incident responses to minimize loss of lives.

• 한국수소및신에너지학회논문집
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• 제14권1호
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• pp.61-68
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• 2003

This paper presents the methodology to analyze flow duration characteristics and performance prediction technique for small hydro power(SHP) Plants and its application. The flow duration curve can be decided by using monthly rainfall data at the most of the SHP sites with no useful hydrological data. It was proved that the monthly rainfall data can be characterized by using the cumulative density function of Weibull distribution and Thiessen method were adopted to decide flow duration curve at SHP plants. And, the performance prediction technique has been studied and development. One SHP plant was selected and performance characteristics was analyzed by using the developed technique, Primary design specfications such as design flowrate, plant capacity, operational rate and annual electricity production for the SHP plant were estimated, It was found that the methodology developed in this study can be a useful tool to predict the performance of SHP plants and candidate sites in Korea.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.7-8
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• 2015

Formwork accounts for 10% of the total construction cost and 30~40% of the framework cost, which is a fairly large part. Various system forms were developed for improved economic feasibility and constructability of formwork and for reduced construction duration. In general, the price of system forms per unit area is higher than that of the conventional method, yet the total construction cost can be reduced through higher reusability and constructability. However, if the reusability of forms is excessively increased to cut down the material cost, it may increase the construction duration, which will result in cost increase. On the other hand, if the reusability is decreased for reduction of construction duration, it may lead to cost increase caused by excessive input of materials. To solve such a problem, an algorithm for simplified reuse planning that meets the requirements of construction duration, cost, quality and safety is required. In this regard, the study intends to perform a fundamental research for development of reuse planning automation algorithms on system forms that are used on girders and beams.

• 한국분무공학회지
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• 제13권1호
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• pp.1-8
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• 2008

It was investigated how fuel injection timing - early injection and later injection - in conjunction with throttle open rate effect the fuel-air mixing characteristics, Engine power, combustion stability and emission characteristics on a DI CNG spark Engine and control system that had been modified and designed according to the author's original idea. It was verified that the combustion characteristics were changed according to fuel injection timings and Engine conditions determined by different throttle open rates and rpm. It was found that the combustion characteristics greatly improved at the complete open throttle rate with an early injection timing and at the part throttle rate with a late injection timing. Combustion duration was governed by flame propagation duration in a late injection timing and by an early flame development duration in an early injection timing. As the result, we discovered that combustion duration is shortened, lean limit is improved, air-fuel mixing conditions controlled, and emissions reduced through control of fuel injection timing according to change of the throttle open rate.

• 대한전기학회논문지:전력기술부문A
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• 제48권5호
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• pp.508-516
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• 1999

This paper presents a method for constructing composite power system effective load duration curves(CMELDC) at load points by Monte Carlo method. The concept of effective load duration curves(ELDC) in power system planning is useful and important in both HLII. CMELDC can be obtained from convolution integral processing of the probability function of unsupplied power and the load duration curve at each load point. This concept is analogy to the ELEC in HLI. And, the reliability indices (LOLP, EDNS) for composite power system are evaluated using CMELDC. Differences in reliability levels between HLI and HLII come from considering with the uncertainty associated with the outages of the transmission system. It is expected that the CMELDC can be applied usefully to areas such as reliability evaluation, probabilistic production cost simulation and analytical outage cost assessment, etc. in HLII, DC load flow and Monte Carlo method are used for this study. The characteristics and effectiveness of thes methodology are illustrated by a case study of the IEEE RTS.