• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.265-270
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• 2007

Polarization imaging systems have been widely used to selectively characterize skin lesions. Nevertheless, current systems are used in single-mode due to the limitations of a fixed polarization mode and a single-working distance of light source, in which uniform light distribution is achieved on target area. To address such limitations, we developed a variable polarization imaging system based on multi-working distance of light source for various clinical diagnoses. In this study, we characterize the imaging system and present experiment results demonstrating its clinical usefulness. The imaging system consists of a CCD color camera, linear polarization filters, and a single-layered LED ring light source which provides uniform light distribution at multi-working distances. The first polarizer was placed on the light source and the second polarizer placed on objective lens provides continuous linear polarization angle from $0^{\circ}\;to\;90^{\circ}$. The clinical efficacy of the imaging system was investigated by acquiring and analyzing clinical images of skin wrinkle and dental plaque. With the experiments, we verified the potential usefulness of the imaging system for other clinical applications.

• 대한산업공학회지
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• 제26권3호
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• pp.257-264
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• 2000

This research suggested a method by which the driver space can be designed to best accommodate the driver's anthropometric characteristics. Three-dimensional manikins and a variable seating buck were developed and used for this study. Manikins were designed with 18 links comprising the 95th percentile male and 5th percentile female data. The seating buck was built to create various driving environments using the distance and the height between the H-point(hip pivot) of the seat and the AHP(accelerator heel point), the angle of the back rest, the angle of the steering wheel, the vertical distance of the steering wheel, and the location of the T.G.S.(transmission gear shift) knob. Measurements of each variable were collected with a coordinate measuring machine by positioning the 3-D manikin under various combinations of the design factors of the seating buck, which was constructed based on mid-size domestic passenger cars. The data were then converted to the joint angles of the driver. The combination of the measurements for an optimal driving environment is suggested by applying sets of the joint angles at which the driver feels comfortable.

• 한국농공학회논문집
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• 제54권3호
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• pp.55-63
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• 2012

Soil properties are not random values which is represented by mean and standard deviation but show spatial correlation. Especially, soils are highly variable in their properties and rarely homogeneous. Thus, the accuracy and reliability of probabilistic analysis results is decreased when using only one random variable as design parameter. In this paper, to consider spatial variability of soil property, one-dimensional random fields of coefficient of consolidation ($C_v$) were generated based on a Karhunen-Loeve expansion. A Latin hypercube Monte Calro simulation coupled with finite difference method for Terzaghi's one dimensional consolidation theory was then used to probabilistic analysis. The results show that the failure probability is smaller when consider spatial variability of $C_v$ than not considered and the failure probability increased when the autocorrelation distance increased. Thus, the uncertainty of soil can be overestimated when spatial variability of soil property is not considered, and therefore, to perform a more accurate probabilistic analysis, spatial variability of soil property needed to be considered.

• Journal of the Optical Society of Korea
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• 제7권2호
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• pp.72-78
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• 2003

It is reported that the spectral loss of photonic crystal fiber (PCF) having a large hole-to-hole distance (~ 10 ${\mu}{\textrm}{m}$) is sensitive to micro- and macrobending when compared with the conventional single-mode fiber. In this paper, we will present the measurement result of the macro- and microbending characteristics of fabricated PCF with large hole-to-hole distance (> 10 ${\mu}{\textrm}{m}$) . For the macrobending experiment, the fiber was simply wound around a circular structure with variable diameter that could be reduced to a few centimeters. For the microbending case, regularly spaced silica rods were attached on a slide glass and pressed against the fiber by loading a stack of metal plates of known weight on the glass. The transmission loss spectrum shows a rather flat response to the to microbending, and this makes the PCF a good candidate for a wideband variable optical attenuator.

• 대한교통학회지
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• 제25권5호
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• pp.23-32
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• 2007

도로전광표지(VMS: Variable Message Signs)는 지능형교통체계(ITS: Intelligent Transport Systems)를 구성하는 주요 서브시스템 중의 하나로서, 불특정 다수를 대상으로 실시간 교통소통 및 돌발상황 정보를 제공해 주는 유용한 기능을 수행한다. VMS에서 표출되는 교통정보는 운전자가 보다 쉽게 이해하고, 눈에 잘 띄고, 적정거리 내에서 판독하기 쉬워야 하는 조건을 만족 시켜야 한다. VMS 판독거리 (Legibility Distance)는 운전자가 VMS 메시지의 문자를 읽기 시작할 수 있는 지점에서 해당 VMS의 설치지점간의 거리를 의미하는데, 도로 및 교통여건, 운전자 특성 등을 고려한 적정 판독거리의 산정은 차량의 주행속도, VMS 메시지 정보량 등과 함께 효과적인 VMS 메시지의 설계 및 운영을 위한 필수조건이라고 할 수 있다. 본 연구의 목적은 실제 도로교통환경에 노출된 운전자의 작업부하를 고려한 보다 현실적인 판독거리 추정모형을 개발하는 것이다. 이를 위해 서울시 도시고속도로, 영동 및 경부고속도로에 설치된 27개 VMS에 대한 운전자의 판독거리, VMS 메시지 특성, 운전자 특성, 도로기하구조 및 교통특성 등의 자료를 수집하고 분석하였다. 실제 주행환경에서 운전자의 판독위치 수집을 위해서는 DGPS(Differential Global Positioning System)장비를 이용하였다. 본 연구의 결과물인 판독거리 모형은 VMS 메시지 설계 및 운영을 위한 기본도구로서 유용하게 활용될 것으로 기대된다.

• 대한교통학회지
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• 제27권1호
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• pp.73-81
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• 2009

여객통행과 화물통행에서 도착지를 선택하는 것은 여러 요인에 영향을 미치지만, 많은 연구들이 도착지의 유인력(Attractiveness)이 중요한 변수라고 제시하고 있다. 유인력 추정방법 중 전통적으로 사용되고 있는 집계형 (Aggregation) 중력모형 보다 개인의 효용을 극대화하는 비집계형 (Disaggregation)모형이 도착지의 효용을 추정하는데 더 효율적이라는 점이 많은 연구들에서 제기되었다. 본 연구는 제3차 전국물류조사의 화물자동차운전자의 통행일지를 이용한 분석으로서 도착지 선택모형을 구축하고 출발시간대, 도착지의 체류시간, 도착지의 유인력 등을 포함하여 이들의 효과를 분석하며, 정책적으로 활용 가능하도록 모형이용을 제안한다. 분석결과, 도착지행태선택모형에서 인구가 많고, 총통행거리가 짧을수록 효용이 큰 것으로 분석되었다. 인구밀도 측면에서 볼 때 화물차는 인구밀집지역을 운행하는 것을 꺼려하는 것으로 분석되었다. 운송거리 측면에서는 소형화물자동차는 운송거리가 짧을수록, 대형화물자동차는 운송거리가 클수록 효용이 큰 것으로 분석되었다. 업종별로 보면, 비영업용 화물자동차는 거리가 짧을수록 유리한 것으로 분석되었으나, 영업용화물자동차의 경우 거리가 길수록 유리한 것으로 나타났다. TOD별 차종별로 살펴보면, 소형화물자동차의 경우 새벽, 오전첨두, 오후첨두에 주로 출발하였으며, 대형화물차는 낮 시간대를 제외한 시간대에 주로 출발하는 것으로 분석되었다.

• Journal of Advanced Marine Engineering and Technology
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• 제40권1호
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• pp.62-68
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• 2016

실내 위치인식 기술 중 하나인 WiFi Fingerprint는 기존의 WiFi access point(AP)의 거리에 따른 신호 세기를 활용하여 위치를 추정하는 편리함 때문에 많은 연구가 이루어지고 있다. 하지만 이 방식은 Radio map에 저장된 Reference point에 의존하기 때문에 다른 방식에 비해 위치의 분해능이 떨어지고 연산량이 많다. 본 논문에서는 이러한 문제를 해결하기 위하여 WiFi와 BLE를 융합한 Log-Distance Path Loss Model 기반의 Radio map 설계 알고리즘을 제안한다. 제안한 알고리즘은 Log-Distance Path Loss Model이 적용된 변수 값을 추출하여 Radio map을 설계하는 방식이며 Median Filter를 적용하여 오차를 개선하였다. 기존 Fingerprint와 비교하여 실험한 결과, 위치의 정확도는 평균 2.747m에서 2.112m로 0.635m 감소되는 것을 확인하였으며 연산량은 AP 환경에 따라 33%이상 감소하는 것을 확인하였다.

• 한국환경과학회지
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• 제25권6호
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• pp.799-815
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• 2016

In this study, according to the reference setting based on the runoff video of 9:00 where the highest water level of 3.94 m has been recorded during the runoff of Cheon-mi Stream in Jeju Island by the attack of Typhoon no. 16 Sanba on September $17^{th}$, 2012, the error rate of long-distance and short-distance velocimetry and real-distance change rate by input error have been calculated and the input range value of reference point by stream has been suggested. In the reference setting process, if a long-distance reference point input error occurs, the real-distance change rate of 0.35 m in the x-axis direction and 1.35 m in y-axis direction is incurred by the subtle input error of 2~11 pixels, and if a short-distance reference point input error occurs, the real-distance change rate of 0.02 m in the x-axis direction and 0.81 m in y-axis direction is incurred by the subtle input error of 1~11 pixels. According to the long-distance reference point setting variable, the velocity error rate showed the range of fluctuation of at least 14.36% to at most 76.06%, and when calculating flux, it showed a great range of fluctuation of at least 20.48% to at most 78.81%.

• 한국국방경영분석학회지
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• 제2권1호
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• pp.127-143
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• 1976

The purpose of this thesis is to study the optimal arrangement of aircraft instrument panels through the human factors approach. Human factors engineering is the process of effectively fitting the human component to the machine component in any man-machine system. The human factors. are especially important to an aircraft pilot who must constantly shift his attention between the instrument panel within the cockpit and the surrounding area of the aircraft. The preliminary part of this study is to find the general patterns of the Korean pilot's eye movements during their various flying maneuvers, and which instruments require the most attention while in flight. It is assumed that all pilots have a general pattern of eye movement when observing the aircraft instrument panel and that an optimum arrangement would be to minimize the eye travel distance between instruments. In this thesis the arrangements of instruments is taken to be the independent variable and the eye travel distance between instruments the dependent variable. la order to compile the information necessary for this study, sixty Korean Air Force pilots were interviewed and requested to complete information forms. These information forms listed various flying maneuvers and listed each instrument used on the instrument panel. The compilation of the information on these completed forms listed the instruments most frequently used by the pilots. The second part of this study was to determine the optimum instrument arrangement. It was necessary to study the various number of possible arrangements of instruments depending upon the number of instruments involved. Therefore, these instruments are grouped by two major functions, The flight instruments were subdivided into three groups, and the engineering instruments were subdivided into six groups. With this subdivision we arrive at the possible number of arrangements of 4,320. Through the simulation method, total eye travel distance for each of these 4,320 arrangements is calculated and the arrangement which appears to be of optimum distance between the most frequently used aircraft instruments is determined. The results of this study indicate that the optimum distance between instruments would be 33,028cm and that the corresponding distance of the instrument panel now being used is 34,288cm. Therefore, an increased efficiency of $3.8\%$ would be realized if the existing aircraft instrument panel were re-arranged according to layout proposed in this thesis.

• 정보과학회 논문지
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• 제43권11호
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• pp.1275-1280
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• 2016

유사 문자열 검색을 위해 기존의 기법들은 우선 후보 문자열 집합을 생성한 후에 후보 문자열을 검증하는 방법을 사용한다. 이때, 유사 문자열 검색의 성능을 결정짓는 가장 중요한 요소는 후보 생성 방법이다. 기존의 기법들은 질의 문자열로부터 고정길이 q-그램들을 선택하고, 선택된 q-그램에 해당하는 역리스트를 이용해 후보 문자열을 생성한다. 본 논문에서는 질의 문자열 내의 가변길이 그램들을 사용하여 후보 문자열을 생성할 수 있는 기법과 질의 문자열로부터 최적의 가변길이 그램들의 조합을 선택하는 동적 프로그래밍 알고리즘을 제안한다. 실험을 통해 제안하는 기법이 기존의 기법들 보다 유사 문자열 검색의 성능을 향상시킴을 보인다.