• 한국강구조학회 논문집
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• 제16권4호통권71호
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• pp.433-442
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• 2004

본 연구는 Eurogode 3 Part 1.3을 근거하여 온도증가에 따른 압축을 받는 냉간성형 C-형강 기둥의 플랜지와 웨브의 탄성국부좌굴 응력 해석 프로그램을 개발하였다. 고온에서 응력-변형률 관계식은 Eurocode 3 Part 1.2를 근거하였다. 온도증가에 따른 압축을 받는 냉간성형 C-형강의 임계온도와 탄성국부좌굴 응력은 본 연구에서 개발한 컴퓨터 프로그램에 의해 해석하였고, 해석 예에 대한 비교 고찰을 하였다.

• 농촌지도와개발
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• 제4권2호
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• pp.399-406
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• 1997

Extension service in Korea has radical changes in accordance with local autonomy acts, 1994, and reformed rural development acts, 1995. According to these acts, the role of the central government is to arrange local extension service carried out by local extension office, to present basic plans on technical knowledge diffusion or farmers training to local government, and so on. Local extension office is a part of local government, and extension service is commited to the local government.

• Journal of Mechanical Science and Technology
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• 제18권8호
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• pp.1358-1367
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• 2004

As a part II of theis research, new local inspection planning strategy is proposed in this paper based on the proposed inspection feature extraction method. In the local inspection planning stage, each feature is decomposed into its constituent geometric elements for more effective inspection planning. The local inspection planning for the decomposed features are performed to determine: (1) the suitable number of measuring points, (2) their locations, and (3) the optimum probing paths to minimize measuring errors and times. The fuzzy set theory, the Hammersley's algorithm and the TSP method are applied for the local inspection planning. Also, a new collision checking algorithm is proposed for the probe and/or probe holder based on the Z-map concept. Finally, the results are simulated and analyzed to verify the effectiveness of the proposed methods.

• 한국융합학회논문지
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• 제13권4호
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• pp.53-61
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• 2022

LNG 저장 작업 중 기계결함, 부주의 등으로 인해 사고가 꾸준히 발생하고 있다. 이전 연구에서는 위험을 미리 감지하는 압력, 온도, 가스 농도, 플로우 측정이 가능한 환경 센서 모듈을 개발하고 누출된 가스량에 따른 응답속도를 측정하였었다. 본 논문에서는 환경 센서 모듈이 측정한 데이터를 SPI, UART, LTE의 유무선 네트워크와 연결된 임베디드 기기들에 안전하게 전송해주는 유무선 통신 모듈의 개발을 제안한다. 먼저 환경 센서와 연동 가능한 데이터 통신 모듈을 설계한다. Local Control Part의 각 장치간 프로토콜과 Local Control Part와 Remote Control Part의 유무선 프로토콜을 설계한다. 이더넷, WiFi, LTE 통신 모듈을 설계하고 임베디드 제어기와 연동 가능한 UART, SPI 채널을 설계하였다. 그 결과, 각 임베디드 기기가 유선, 무선 동시 통신하면서 환경 센서 모듈이 측정한 데이터를 전송함을 UI(User Interface)를 통해 확인할 수 있었다.

• 소성∙가공
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• 제24권5호
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• pp.354-360
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• 2015

AHSS (Advanced High Strength Steels) has been increasingly employed by global automotive OEMs in order to satisfy strengthened regulations and reduce weight for fuel efficiency. Hot stamping using boron steels in AHSS increases not only formability but also strength. The typical hot-stamped automotive part is the center pillar that is critical for vehicle side impact. However, the hot-stamped part can be risky for the passenger safety caused by brittle fracture under a vehicle collision. The high power diode laser is suitable for the heat treatment giving AHSS increased elongation that prevents brittle fracture in car crash. Therefore, local softening by laser heat treatment for energy absorption area on the hot-stamped part improves crash-worthiness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.472-478
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• 2000

An experimental study is performed to analyze flow structures behind a local suction/blowing in a flat-plate turbulent boundary layer, The local forcing is given to the boundary layer flow by means of a sinusoidally oscillating jet issuing from a thin spanwise slot at the wall. The Reynolds number based on the momentum thickness is about $Re_{\theta}=1700$. The effects of local forcing are scrutinized by altering the forcing frequency $(0.011{\leq}f^+{\leq}0.044)$. The forcing amplitude is fixed at $A_0=0.4$. It is found that a small local forcing reduces the skin friction, and this reduction increases with the forcing frequency. A phase-averaging technique is employed to capture the coherent structures. Velocity signals are decomposed into a periodic part and a fluctuating part. An organized spanwise vortical structure is generated by the local forcing. The larger reduction of skin friction for the higher forcing frequencies is attributed to the diminished adverse effect of the secondary vortex. An investigation of the random fluctuation components reveals that turbulent energy is concentrated near the center of vortical structures.

• 한국강구조학회 논문집
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• 제17권4호통권77호
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• pp.491-498
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• 2005

본 연구는 온도상승에 따른 압축을 받는 I-형강 보의 플랜지와 웨브의 국부좌굴응력해석을 위한 컴퓨터프로그램과 항복파괴전에 I-형강 보의 플랜지와 웨브에 국부좌굴이 일어나지 않을 최적 폭-두께비를 구할 수 있는 최적알고리즘의 개발이다. 본 연구에서 사용한 고온에 있어서 강재의 응력-변형도 관계식은 EC3(Eurocode3) Part1.2(2000b)를 근거하였다. 본 연구에서 국부좌굴응력과 최적 폭-두께비는 항복응력, 플랜지와 웨브의 국부좌굴계수와 폭-두께비 영향을 고려하여 해석하였다. 그리고 본 연구의 컴퓨터 프로그램을 적용한 설계 예를 들었다.

• 한국환경과학회지
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• 제13권4호
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• pp.367-376
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• 2004

In urban area, thermal pollution associated with heat island phenomena is generally regarded to make urban life uncomfortable. To overcome this urban thermal pollution problem, urban planning with consideration of urban climate, represented by the concept of urban ventilation lane, is widely practiced in many countries. In this study, the prevailing wind ventilation lane of a local winds in Daegu during the warm climate season was investigated by using surface wind data and RAMS(Reasonal Atmospheric Model System) simulation. The domain of interest is the vicinity of Daegu metropolitan city(about 900 $km^{2})$ and its horizontal scale is about 30km. The simulations were conducted under the synoptic condition of late spring with the weak gradient wind and mostly clear sky. From the numerical simulations, the following two major conclusions were obtained: (1)The major wind passages of the local circulation wind generated by radiative cooling over the mountains(Mt. Palgong and Mt. Ap) are found. The winds blow down along the valley axis over the eastern part of the Daegu area as a gravity flow during nighttime. (2)After that time, the winds blow toward the western part of Daegu through the city center. As the result, the higher temperature region appears over the western part of Daegu metropolitan area.

• International Journal of Aeronautical and Space Sciences
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• 제17권1호
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• pp.109-119
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• 2016

When manufactured parts undergo large deformations during the manufacturing process, the global specifications of a part based on the concept of tolerance zone defined in the ISO 1101 standard [1] enable one to control the part's global defects. However, the extent of this tolerance zone is too large when the objective is to minimize local defects, such as hollows and bumps. Therefore, it is necessary to address local defects and global defects separately. This paper refers to the ISO 10579 standard [2] for flexible parts, which enables us to define a stressed state in order to measure the part by straightening it to simulate its position in the mechanism. The originality of this approach is that the straightening operation is performed numerically by calculating the displacement of a cloud of points. The results lead to a quantification of the global defects through various simple models and enable us to extract local defects. The outcome is an acceptable tolerance solution. The procedure is first developed for the simple example of a steel bar with a rectangular cross section, then applied to an industrial case involving a complex 3D surface of a turbine blade. The specification is described through ISO standards both in the free state and in the straightened state.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1418-1433
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• 2019

In computer graphics, 3D mesh segmentation is a challenging research field. This paper presents a 3D mesh model segmentation algorithm that focuses on removing exterior salient parts from the original 3D mesh model based on prominent feature points and marching plane. To begin with, the proposed approach uses multi-dimensional scaling to extract prominent feature points that reside on the tips of each exterior salient part of a given mesh. Subsequently, a set of planes intersect the 3D mesh; one is the marching plane, which start marching from prominent feature points. Through the marching process, local cross sections between marching plane and 3D mesh are extracted, subsequently, its corresponding area are calculated to represent local volumes of the 3D mesh model. As the boundary region of an exterior salient part generally lies on the location at which the local volume suddenly changes greatly, we can simply cut this location with the marching plane to separate this part from the mesh. We evaluated our algorithm on the Princeton Segmentation Benchmark, and the evaluation results show that our algorithm works well for some categories.