• 대한토목학회논문집
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• 제31권3D호
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• pp.403-412
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• 2011

도로의 곡선부는 운전자의 시각변화가 현격하게 발생하여 속도편차가 크게 나타나며, 다양한 원인에 의해 직선부 보다 위험도가 더 큰 것으로 파악된다. 특히, 야간 또는 기상악화로 인한 시선유도시설의 시인성 마비는 도로선형에 대한 정보를 왜곡시켜 운전자의 안전을 위협할 뿐만 아니라, 주행속도에 영향을 미쳐 사고위험도를 증가시키게 된다. 이에 운전자의 시인성을 향상시킬 수 있는 시선유도시설물의 설치 및 관리가 절실히 요구된다. 본 연구는 곡선부에 기 설치 운영 중인 재귀반사식 시선유도시설과 도로안전을 향상시키기 위해 개발된 내부조명식 시선유도시설을 대상으로 설문조사와 주행실험을 실시하였다. 그 결과, 재귀반사식 보다 내부조명식 시선유도시설에서 시인성, 속도감속 필요성, 안전성에 대한 효과가 큰 것으로 분석되었다. 또한, 내부조명식 시선유도시설이 설치된 곡선부를 진입할 경우 주행차량의 완만한 속도감속으로 인해 주행 안전성을 확보하는 것으로 분석되었다. 결과적으로, 내부조명식 곡선부 시선유도시설은 기존 재귀반사식 시선유도시설에 비해 운전자에게 도로선형에 대한 정보를 더욱 효과적으로 제공함으로써, 곡선부 교통사고 위험도를 줄일 수 있으며, 도로 곡선부 구간의 교통안전 개선대안으로 이용될 수 있을 것으로 판단된다.

• 한국지반공학회논문집
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• 제15권6호
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• pp.111-120
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• 1999

투수성 중간복토재로 인한 침출수 흐름 거동과 누적수위 저감을 위해 양수정을 이용한 수직배수공법의 적용 가능성을 흐름 수치해석 프로그램인 MODFLOW를 이용하여 분석하였다. 현장 양수시험과 순간충격시험으로부터 획득한 투수계수와 저류계수를 이용하여(장연수 외, 1999) 현장의 수리상황을 수치적으로 검증한 후, 매립지에서 누적수위를 저감하기 위한 양수정의 최적양수율, 영향반경, 수평드레인의 효용성을 분석하였다. 본 수치해석 결과 대상지역의 지반조사결과(장연수 외, 1999)에서도 나타났던 저투수성의 중간 복토재로인한 매립지내의 수직흐름을 방해하는 차수효과가 다시 확인되었다. 단정 양수시 120 ton/day까지 가능하였던 양수율은 수평드레인 추가후 300 ton/day까지 증가하였으나 드레인 길이가 시간-수위강하 곡선에 큰 영향을 주지는 않았다.

• 대한치과교정학회지
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• 제44권5호
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• pp.254-262
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• 2014

Objective: The purpose of this study was to evaluate the relation between idiopathic scoliosis and facial deformity in the horizontal, vertical, and anteroposterior planes. Methods: A total of 123 female patients aged 14 years or older, who visited the Spine Clinic at the Department of Orthopedics, Korea University Guro Hospital for treatment of idiopathic scoliosis, were enrolled. Whole-spine anteroposterior and lateral radiographs were taken with the patient in a naturally erect position, and frontal and lateral cephalograms were taken in an erect position with the Frankfort horizontal line parallel to the floor. Scoliosis was classified according to the Cobb angle and Lenke classification of six curve types. Cephalometric tracing in all cases was carried out with V-Ceph 5.5 by the same orthodontist. The Kruskal-Wallis test was performed to determine whether any relation existed between each group of the idiopathic scoliosis classification and the cephalometric measurements of frontal and lateral cephalograms. Results: The measurements did not reveal any significant association between the Cobb angle and cephalometric measurements and between the curve type based on the Lenke classification and cephalometric measurements. Conclusions: Based on the results of this study, no apparent relation was observed between the severity of scoliosis and facial form variations in idiopathic scoliosis patients.

• 한국지반공학회논문집
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• 제18권2호
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• pp.87-96
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• 2002

자가굴착식 프레셔미터를 이용한 변형률 유지 시험은 점성토 지반의 수평방향 압밀계수를 추정하는데 있어 효과적으로 사용되고 있다. Clarke등(1979)이 제시한 일반적인 해석 방법은 여러 가지 단순화한 가정으로 인해 압밀계수산정에 문제점을 내포하고 있다. 따라서, 본 논문에서는 실제 시험 과정 및 조건들을 최대한 반영하기 위하여 프레셔미터 시험기의 유한한 길이, 계파시의 부분배수, 소산시험 시작시의 공동 변형률 등의 여러 가지 해석 조건들이 초기 과잉간극수압의 분포 및 소산 거동에 미치는 영향을 고려한 유한요소해석을 수행하였다. 그 결과, 수평방향 압밀계수를 추정하는데 필요한 50% 압밀도에서의 시간계수를 제안하였고, 이를 국내 2개 현장에서 수행한 변형률 유지시험에 적용하여 압밀계수를 산정하고, 다른 현장 시험 및 실내시험 결과와 비교.분석하여 그 적용성을 확인하였다.

• 대기
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• 제28권2호
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• pp.223-232
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• 2018

The Global-Korean aviation Turbulence Guidance (G-KTG) system is developed using the operational Global Data Assimilation and Prediction System of Korea Meteorological Administration with 17-km horizontal grid spacing. The G-KTG system provides an integrated solution of various clear-air turbulence (CAT) diagnostics and mountain-wave induced turbulence (MWT) diagnostics for low [below 10 kft (3.05 km)], middle [10 kft (3.05 km) - 20 kft (6.10 km)], and upper [20 kft (6.10 km) - 50 kft (15.24 km)] levels. Individual CAT and MWT diagnostics in the G-KTG are converted to a 1/3 power of energy dissipation rate (EDR). 12-h forecast of the G-KTG is evaluated using 6-month period (2016.06~2016.11) of in-situ EDR observation data. The forecast skill is calculated by area under curve (AUC) where the curve is drawn by pairs of probabilities of detection of "yes" for moderate-or-greater-level turbulence events and "no" for null-level turbulence events. The AUCs of G-KTG for the upper, middle, and lower levels are 0.79, 0.69, and 0.63, respectively. Comparison of the upper-level G-KTG with the regional-KTG in East Asia reveals that the forecast skill of the G-KTG (AUC = 0.77) is similar to that of the regional-KTG (AUC = 0.79) using the Regional Data Assimilation and Prediction System with 12-km horizontal grid spacing.

• 산업기술연구
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• 제28권B호
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• pp.91-99
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• 2008

Applicability of existing methods of predicting consolidation settlement was assessed by analyzing results of centrifuge tests modelling self-weight consolidation of soft marine clay. From extensive literature review about self-weight consolidation of soft marine clays located in southern coast in Korea, constitutive relationships of void ratio-effective stress-permeability and typical self-weight consolidation curves with time were obtained by centrifuge model experiments. For the condition of surcharge loading, exact solution of consolidation settlement curve was obtained by Terzaghi's consolidation theory and was compared with the results predicted by currently available methods such as Hyperbolic method, Asaoka's method, Hoshino's method and ${\sqrt{S}}$ method. All methods were found to have their own inherent error to predict final consolidation settlement. From results of analyzing the self-weight consolidation with time by using those methods, Asaoka's method predicted the best. Hyperbolic method predicted relatively well in error range of 2~24% for the case of showing the linearity in the relationship between T vs T/S in the stage of consolidation degree of 60~90 %. For the case of relation curve of T vs $T/S^2$ showing the lineality after the middle stage, error range from Hoshino method was close to those from Hyperbolic method. However, Hoshino method is not able to predict the final settlement in the case of relation curve of T vs $T/S^2$ being horizontal. For the given data about self-weight consolidation after the middle stage, relation curve of T vs T/S from ${\sqrt{S}}$ method shows the better linearity than that of T vs $T/{\sqrt{s}}$ from Hyperbolic method.

• 디지털융복합연구
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• 제12권10호
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• pp.283-289
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• 2014

PRT(Personal Rapid Transit) 시스템은 자동차를 대체할 수 있는 지속 가능한 친환경 미래교통 수단으로 최근 국내외적으로 활발한 연구가 진행 중이다. 이러한 PRT 시스템의 중요한 특징 중 하나는 저비용으로 건설 운영될 수 있다는 것이다. 본 연구에서는 PRT 주행선로에 대해 차량의 주행안정성을 고려한 최적 평면 선형에 대한 기초 연구를 수행하였다. 설계 최고속도로 주행 시 곡선반경, 완화곡선 길이, 캔트(편경사)와 같은 주요 매개변수들에 대해 차량동역학 해석을 수행하였으며 최적선형 설계(안)을 제시하였다. 해석결과, 이론값을 만족함을 알 수 있었으며 기준 완화의 가능성도 확인할 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.3-25
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• 2010

The paper deals with two bearing capacity problems of shallow footing under combined loading. The first is a FEM study of shallow strip footing on two-layer clay deposits subjected to a vertical, horizontal and moment combined loading, while the second is a centrifuge study of shallow rectangular footing on dry sand under double eccentricity. The FEM results revealed that the existence of top soft layer sensitively affects more on horizontal and moment capacity than vertical capacity for cases of footing on soft clay overlying stiff clay. Practical design charts are presented to evaluate bearing capacities of footing for various combinations of the ratio of the depth of the upper layer to the footing width and the ratio of undrained strength of the upper layer to that of the lower. The centrifuge tests indicated that current design practice of calculating failure load of rectangular surface footing under double eccentricity underestimates the centrifuge loading test data. This trend is more marked when the eccentricity becomes larger. The decreasing trend in failure load with an increase of double eccentricity is rather uniquely expressed by a single curve, using a newly defined resultant eccentricity and the diagonal length of the footing base.

• 한국도로학회논문집
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• 제15권3호
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• pp.103-115
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• 2013

PURPOSES: The purpose of this study is to develop a method for distribution between superelevation and side friction factor by increasing design speed. METHODS: First of all, a method for distribution between superelevation and side friction factor and a theory for the functional formula of side friction factor in compliance with horizontal radius applied in South Korea and the United States are considered. Especially, design speed of 140km/h and numerical value of design elements are applied to the theory for the functional formula of side friction factor in AASHTO's methods. Also, the anxiety EEG upon running speed is measured to reflect ergonomic characteristics through field experiments at seven curve sections of the West Coast Freeway, and this data is applied to graph for the functional formula of side friction factor. RESULTS : Matching side friction factor against the anxiety EEG, the results that a critical points of driver's anxiety EEG sharply increase locate under existing parabola are figured out. CONCLUSIONS : Therefore, we could get a new type of the functional formula that driver's driving comfortability is guaranteed if the existing the functional formula of side friction factor goes down under boundary of the critical points of the anxiety EEG.

• Journal of Astronomy and Space Sciences
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• 제20권4호
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• pp.359-364
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• 2003

In this paper, we present multi-sensor data fusion for telematics application. Successful telematics can be realized through the integration of navigation and spatial information. The well-determined acquisition of vehicle's position plays a vital role in application service. The development of GPS is used to provide the navigation data, but the performance is limited in areas where poor satellite visibility environment exists. Hence, multi-sensor fusion including IMU (Inertial Measurement Unit), GPS(Global Positioning System), and DMI (Distance Measurement Indicator) is required to provide the vehicle's position to service provider and driver behind the wheel. The multi-sensor fusion is implemented via algorithm based on Kalman filtering technique. Navigation accuracy can be enhanced using this filtering approach. For the verification of fusion approach, land vehicle test was performed and the results were discussed. Results showed that the horizontal position errors were suppressed around 1 meter level accuracy under simulated non-GPS availability environment. Under normal GPS environment, the horizontal position errors were under 40㎝ in curve trajectory and 27㎝ in linear trajectory, which are definitely depending on vehicular dynamics.