• 한국ITS학회 논문지
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• 제19권2호
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• pp.36-47
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• 2020

본 연구는 고속도로 내 상습 지정체 구간 개선을 위해 도로 용량을 증대시키는 대표적인 교통 운영 기법인 갓길차로제 시행의 효과를 분석하는 것을 목적으로 한다. 갓길차로 운영은 차로 확장 등 큰 규모의 공사 없이 첨두시 교통소통을 개선하는 효과가 있어 잦은 정체 구간의 교통 정체 개선 대책으로 활발히 사용되어 왔다. 국내의 경우 경부고속도로, 영동고속도로, 서울외곽순환고속도로에서 갓길차로를 운영 중에 있으며, 단계적으로 운영을 증가시켜가는 추세이다. 이에 따라 본 연구에서는 갓길차로의 운영 전후 효과 분석을 위해 1) 시공도 기반 개별 갓길차로 운영 전후 효과분석, 2) 도로 축 단위 갓길차로 운영 전후 효과 분석으로 나누어 종합적인 분석을 수행하였다. 이를 통해 본 연구는 향후 고속도로 내 갓길차로 설치 및 효율적인 교통운영관리에 기여하고자 한다.

• 대한원격탐사학회지
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• 제12권2호
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• pp.111-125
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• 1996

GMS 적의영상 자료와 적외 파장의 휘도온도(TBB)자료를 이용하여 태풍의 중심 위치와 강도를 예측하는 기법을 개발하 였다. 먼저 TBB의 각 온도대 별로 색을 주어 분석한 구름 패턴과 구름 밴드의 특이한 형태를 이해함으로써 태풍의 중심 위치를 결정하였다. 다음으로 태풍의 강도를 예측하기 위하여 태풍 중심 주위의 TBB값과 태풍 중심기압(혹은 최대풍속)과의 상관관계를 구하여 보았다. 그 결과 두 변 수 사이에는 일정한 시간타(24시간)를 수반하는 상관관계가 있음을 알았다. 특히 태풍 중심으로부터 300 km 이내 영역의 TBB의 평균값이 24시간 후의 태풍 중심기압(혹은 최대풍속)과 밀접한 관련이 있음이 밝혀졌다. 이러한 관계로부터 태풍 중심기압(혹은 최대풍속)을 예측할 수 있는 회귀식을 산출하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.533-537
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• 2003

Compared to sintered polycrystalline diamond (PCD), the deposited thin film diamond has a great advantage on the fabrication of cutting tools with complex geometries such as drills. Because of high performance in high speed machining non-ferrous difficult-to-cut materials in the field of automobiles industry, aeronautics and astronautics industry, diamond-coated drills find large potentialities in commercial applications. However, the poor adhesion of the diamond film on the substrate and high surface roughness of the drill flute adversely affect the tool lift and machining quality and they become the main technical barriers for the successful development and commercialization of diamond-coated drills. In this paper, diamond thin films were deposited on the commercial WC-Co based drills by the electron aided hot filament chemical vapor deposition (EACVD). A new multiple coating technology based on changing gas pressure in different process stages was developed. The large triangular faceted diamond grains may have great contribution to the adhesive strength between the film and the substrate, and the overlapping ball like blocks consisted of nanometer sized diamond crystals may contribute much to the very low roughness of diamond film. Adhesive strength and quality of diamond film were evaluated by scanning electron microscope (SEM), atomic force microscope (AFM), Raman spectrum and drilling experiments. The ring-block tribological experiments were also conducted and the results revealed that the friction coefficient increased with the surface roughness of the diamond film. From a practical viewpoint, the cutting performances of diamond-coated drills were studied by drilling the SiC particles reinforced aluminum-matrix composite. The good adhesive strength and low surface roughness of flute were proved to be beneficial to the good chip evacuation and the decrease of thrust and consequently led to a prolonged tool lift and an improved machining quality. The wear mechanism of diamond-coated drills is the abrasive mechanical attrition.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.381-382
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• 2002

The Fluid film between the valve plate and the cylinder block was measured by use of a gap sensor and the mercury-cell slip ring unit under real working conditions. During the operating periods, experiments with discharge pressure, revolution speed, and valve geometry was carried out for the fluid film on the valve plate. To investigate the effect of the valve shape, we designed two valve plates each having a different shape; the first valve plate was a plane valve plate. while the second valve plate was a spherical valve plate. It was noted that these two valve plates observed different aspects of the fluid film characteristics between the cylinder block and the valve plate. The leakage flow rate and the shan torque were also investigated in order to clarify the difference between these two types of valve plates. From the results of this study. we found that the spherical valve plate estimated good fluid film patterns and performance more than the other valve plate in oil hydraulic axial piston pumps.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1993년도 춘계학술대회 및 공장견학
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• pp.39-53
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• 1993

The minimum oil film thickness(MOFT) in the connecting-rod bering of a 1.5 liter, L-4, gasoline engine is measured up to 5500 rpm and calculated to study the dynamically loaded engine bearing. Short bearing approximation and Mobility method are used for theoretical analysis of oil film charactrtistics. And cylinder pressure, crank-pin surface temperature and bearing tenp ture are measured as the input data of theoretical analysis. The MOFT are measured by the total capacitance method(TCM). To improve the reliability of the test results, a reasonable detmuuination method of bearing clearance is introduced and used, and the effects of cavitation and aeration on the test results are neglected. The crankshaft is grounded by means of a slip ring. A scissor type linkage system was developed to measure the MOFT and bearing temperature. The effects of engine speed, load and oil viscosity on the measured and calculated minimum oil film thicknesses are investigated at 1500 to 5500 rpm. From the comparison between the measured and calculated MOFT, it is found that a qualitative similarity exists between them, but in all cases, the measured MOFT are smaller than those calculated.

• 폴리머
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• 제25권5호
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• pp.699-706
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• 2001

연신온도, 연신속도, 연신비 등 연신 조건에 따른 poly(ethylene 2,6-naphthalate) (PEN)의 배향상태 변화를 살펴보았다. 연신온도가 낮을수록 연신속도가 빠를수록 연신비에 따라 큰 복굴절 값을 보이며 FT-IR ATR dichroism 방법으로 구한 배향 특성도 복굴절의 실험결과를 뒷받침하였다. PEN을 $120^{\circ}C$에서 연신하면 무정형사슬 배향함수 ($f_a$)가 연신속도가 빠를수록 높은 값을 갖지만 $141^{\circ}C$에서 연신하면 반대로 연신속도가 빠를수록 낮은 값을 갖게 된다. 이러한 경향은 결정화 속도와 사슬 이완속도와의 관계로부터 설명이 가능하다. X-선 회절 실험 결과로부터 PEN의 naphthalene ring 구조가 필름표면에 평행하게 배열됨을 확인할 수 있었다.

• 전기학회논문지
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• 제56권1호
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• pp.57-65
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• 2007

Along with the development of power electronics and magnetic materials, permanent magnet (PM) brushless direct current (BLDC) motors are now widely used in many fields of modern industry BLDC motors have many advantages such as high efficiency, large peak torque, easy control of speed, and reliable working characteristics. However, Compared with the other electric motors without a PM, BLDC motors with a PM have inherent cogging torque. It is often a principle source of vibration, noise and difficulty of control in BLDC motors. Cogging torque which is produced by the interaction of the rotor magnetic flux and angular variation in the stator magnetic reluctance can be reduced by sinusoidal air-gap flux density waveform due to reduction of variation of magnetic reluctance. Therefore, this paper will present a design method of magnetizing system for reduction of cogging torque and low manufacturing cost of BLDC motor with isotropic bonded neodynium-iron-boron (Nd-Fe-B) magnets in ring type by sinusoidal air-gap flux density distribution. An analytical technique of magnetization makes use of two-dimensional finite element method (2-D FEM) and Preisach model that expresses the hysteresis phenomenon of magnetic materials in order for accurate calculation. In addition, For optimum design of magnetizing fixture, Factorial design which is one of the design of experiments (DOE) is used.

• 기술사
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• 제34권4호
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• pp.41-47
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• 2001

The paper describes SR3 (Synchronous Round Robin with Reservations), a collision-free medium access control protocol for all-optical slotted packet networks based on WDM multi-channel ring topologies where nodes are equipped with one fixed-wavelength receiver and one wavelength-tunable transmitter SR3 is derived from the SRR and MMR protocols previously proposed by the same authors for the same class of all-optical networks. SRR and MMR already achieve an efficient exploitation of the available bandwidth, while guaranteeing a throughput-fair access to each node. SR3, In addition, allows nodes to reserve slots. thereby achieving a stronger control on access delays; it is thus well suited to meet tight delay requirements, as it is the case for multimedia applications. Simulation results show that SR3 provides very good performance to guaranteed qualify traffic, but also brings signigicant performance improvements for best-effort traffic. Energy effciency is an important issue for optical network since they must rely on their batteries. We present a novel MAC protocol that achieves a good energy efficiency of optical interface of the network and provides support for diverse traffic types and QoS. The scheduler of the base station is responsible to provide the required QoS to connections on the optical link and to minimise the amount of energy spend by the High speed Network. The main principles of the MaC protocol are to avoid unsuccessful actions, minimise the number of transitions , and synchronise the mobile and the base-station. We will show that considerable amounts of energy can be saved using these principles.

• Journal of Chest Surgery
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• 제10권1호
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• pp.38-43
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• 1977

With the adevance of widespread mechanization and high-speed era, the incidence of traumatic rupture of the tracheobronchial tree has been increased considerably. We have experienced these diseased of the 3 cases in our department. The first case was a 25 year old male who was severe dyspneic and subcutaneous emphysema, hemoptysis, and hemopneumothorax of both side were noted. During tracheostomy, it was found that the 2net ring of the trachea was ruptured. No definitive procedure was made on admission. Corrective surgery was performed with end-to-end anastomosis on 31 post-traumatic day. The second case was a 43 year old female who received multiple stab wounds on the anterior neck and it was found that the cricoid cartilage was transected partially. The injured cartilage was approximated with interrupted suture of No. 600 wire. The third case was a 19 year old male who had sustained a compression chest injury without external wound or rib fracture. At five days after trauma, he had suffered from dyspnea, and obstruction of the left main bronchus due to traumatic bronchial rupture was confirmed by means of bronchoscopy and bronchography at two weeks after the trauma. End-to-end anastomosis of the bronchus was performed and the left lung was aerated well. Mild postoperative stenosis of trachea was remained in the first case. Others were uneventful.

• 대한교통학회지
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• 제23권5호
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• pp.57-64
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• 2005

최근 들어 경부고속철도 천성산 구간, 외곽순환도로 사패산터널 등 주요 국가건설사업이 주민 또는 환경단체의 반대로 지연되거나 표류하는 사례가 많이 발생하고 있다. 한국사회의 민주주의 발달, 주민의 참여의식 강화, 환경에 대한 관심 증대 등을 고려할 때 이러한 분쟁이 발생하는 것은 자연스러운 일일 수도 있으나 분쟁의 장기화에 따른 사회적 비용의 증대, 집단간의 갈등심화를 고려할 때 분쟁요인을 사전에 해결하고 국가건설사업을 원활하게 추진하려는 노력이 필요하다. 본 연구에서는 우리보다 한발 앞서 이러한 갈등을 경험하고 이를 해소하기 위하여 주민참여 제도를 활발히 운영하고 있는 미국의 PI제도의 기법들을 살펴보고 이와 비교하여 현재 우리나라의 주민참여제도의 미비점 및 개선방안을 제시하고자 한다.