• 한국지반신소재학회논문집
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• 제16권4호
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• pp.163-176
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• 2017

개별요소법(Discrete Element Method, DEM)은 토목공학 등 입자형태의 재료를 다루는 분야에서 다양하게 이용된다. 본 연구에서는 DEM 기법에 근거한 입자 역학 전용 해석 상용 소프트웨어를 사용하여 면판형 토압식 쉴드TBM 굴착성능을 평가하기 위한 수치 해석을 수행하였다. TBM에 대한 해석은 커터헤드의 회전속도가 다른 두 가지 조건에 대해 수행되었다. 해석 모델의 직경은 6.64m이며 6개의 스포크를 갖는 것으로 작성되었다. 또한, 37개의 프리커터와 98개의 스크래퍼가 각 스포크에 모델링 되었다. 해석결과를 통해, 커터헤드면과 쉴드, 절삭 도구에 작용하는 압축력과 커터헤드면에서 발생하는 저항 토크의 크기를 검토하였으며 스크루 오거를 통해 배출되는 토사량에 대해서는 각각 단위 시간당 배토량과 누적 배토량을 검토하였다.

• 한국컴퓨터그래픽스학회논문지
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• 제26권3호
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• pp.21-29
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• 2020

본 연구는 패션에 대한 첨단 시뮬레이션 기술로 가상 의류 시각화를 지원하는 3D 패션 디자인 소프트웨어인 CLO 3D와 증강현실 어플리케이션 제작을 위한 모바일 플랫폼 증강현실 개발 도구인 vuforia를 활용하여 유니티 엔진 개발 환경에서 대화식 구조의 디지털 패션 콘텐츠 제작을 위한 공정을 정의한다. CLO 3D 소프트웨어를 통해 패턴, 재봉선, 텍스쳐 등의 작업을 거쳐 가상 의류 모델을 제작하는 방법과 유니티 엔진 개발 환경에서 vuforia 개발 도구의 기능과 속성 들을 활용하여 컴퓨터 비전 기술 기반의 증강현실 콘텐츠를 제작하는 방법을 정리한다. 그리고 패션 디자이너, 디렉터 등 실무 사용자의 관점에서 현실적으로 활용 가능한 새로운 방식의 증강현실 디지털 패션 콘텐츠를 정의한 제작 공정의 흐름으로 직접 제작함으로써 활용 방법을 제시한다.

• International Journal of Concrete Structures and Materials
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• 제11권2호
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• pp.327-341
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• 2017

Openings in slabs are usually required for many different applications such as aeriation ducts and air conditioning. Opening in concrete slabs due to cutouts significantly decrease the member stiffness. There are different techniques to strengthen slabs with opening cutouts. This study presents experimental and numerical investigations on the use of Carbon Fiber Reinforced Polymers (CFRP) as strengthening material to strengthen and restore the load carrying capacity of R.C. slabs after having cutout in the hogging moment region. The experimental program consisted of testing five (oneway spanning R.C. flat slabs) with overhang. All slabs were prismatic, rectangular in cross-section and nominally 2000 mm long, 1000 mm width, and 100 mm thickness with a clear span (distance between supports) of 1200 mm and the overhang length is 700 mm. All slabs were loaded up to 30 kN (45% of ultimate load for reference slab, before yielding of the longitudinal reinforcement), then the load was kept constant during cutting concrete and steel bars (producing cut out). After that operation, slabs were loaded till failure. An analytical study using finite element analysis (FEA) is performed using the commercial software ANSYS. The FEA has been validated and calibrated using the experimental results. The FE model was found to be in a good agreement with the experimental results. The investigated key parameters were slab aspect ratio for the opening ratios of [1:1, 2:1], CFRP layers and the laminates widths, positions for cutouts and the CFRP configurations around cutouts.

• 한국항해학회지
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• 제8권2호
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• pp.51-70
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• 1984

In the North Pacific Ocean a lot of large waves set up in winter, affected by continued winds and swells owing to severe extratropical cyclones. Under this sea condition, if the ship is about 100,000L/T (in deadweight capacity tonnage), we can't find the danger involved in the ship at sea apparently. But when we compare the seaworthiness of ship's building strength with the stress given to the hull by waves, we can't insist that the former be more stronger than the latter. As a result, VLCC is in danger of destroying and cutting for lack of longitudinal strength in heavy weather. Up to this time, Naval Architects have actively studied the relation between ship's longitudinal strength and waves as a ship's projector; however, actually, they have never made more profound study on the problem of longitudinal strength in relation to navigation. The main puprpose of this thesis is to clarify these vivid actual states of ship's trouble unknown to ship's masters. In this thesis we picked up VLCC Pan Yard, a vessel of Pan Ocean Bulk Carrier company's, as a model ship. And in the North Pacific Ocean, we have chosen for this research the basins where the wind speed and the wave height are greater than average. The data used this thesis are quotes from the "winds and waves of the North Pacific Ocean('64-'73)", and wind speed more than 30 knots was made use of as an ocject of this study. By usinh the ITTC wave spectrum, we found out the significant waves for every 5 knots within the range of 20 knots to 45 knots of wind speed. According to this H1/1000 was calculated. The stress of ship's hull is determined by ship's speed and wave height. We compared the ship's longitudinal strength with a planned wave height by rules of several famous classification societies in the world. In the last analysis, we found out that ship's present planned strength in heavy weather is not enough. Finally we made a graph for avoiding heavy weather, with which we studied safe ship's handling in the North pacafic Ocean in winter.

• 농업과학연구
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• 제22권1호
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• pp.11-23
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• 1995

The CAD/CAM system for the manufacturing automation is the newest technology in mechanical engineering area and becomes the important research subject nowadays. Most of all hardwares and softwares for the CAD/CAM system used in the our manufacturing companies such as automobile company are developed by the foreign country and the purchasing price of them is very expensive but their applicability to a certain area is very limited. This study was conducted to develope a CAD/CAM system for the design and the automatic manufacturing of the iron pattern shaped with 3 - dimensional free curved surface, and to test its applicability to the design and the manufacturing of the rotary blade. The results obtained from the study are as follow; 1. The CAD system which can process graphic procedures from the free curved surface shaped data was developed with personal computer. 2. The CAM main program was developed. This main program could produce CL data from CAD data file by checking the tool interference according to the cutting mode. 3. The sub. program which can simulate the tool trace from the CL data was developed. 4. The post processor for the Deckel FP2NC NC milling machine from CL data file was developed and the sub program could transmit NC program through modem to NC milling machine was developed. 5. The developed CAM system seemed to be applicable to any other system. Because the measuring results of the cross sectional thickness of the plastic model from the manufacturing iron pattern by the system showed that this system could properly check the tool interference. 6. In took 75~90 hours to manufacture two iron patterns of rotary blade. For the sake of convenience in applying to the other systems, this system was developed in BASIC and FORTRAN computer language and minimum portion of machine language as possible.

• Journal of Information Processing Systems
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• 제8권3호
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• pp.409-420
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• 2012

The decision-making by agents in games is commonly based on reinforcement learning. To improve the quality of agents, it is necessary to solve the problems of the time and state space that are required for learning. Such problems can be solved by Macro-Actions, which are defined and executed by a sequence of primitive actions. In this line of research, the learning time is reduced by cutting down the number of policy decisions by agents. Macro-Actions were originally defined as combinations of the same primitive actions. Based on studies that showed the generation of Macro-Actions by learning, Macro-Actions are now thought to consist of diverse kinds of primitive actions. However an enormous amount of learning time and state space are required to generate Macro-Actions. To resolve these issues, we can apply insights from studies on the learning of tasks through Programming by Demonstration (PbD) to generate Macro-Actions that reduce the learning time and state space. In this paper, we propose a method to define and execute Macro-Actions. Macro-Actions are learned from a human subject via PbD and a policy is learned by reinforcement learning. In an experiment, the proposed method was applied to a car simulation to verify the scalability of the proposed method. Data was collected from the driving control of a human subject, and then the Macro-Actions that are required for running a car were generated. Furthermore, the policy that is necessary for driving on a track was learned. The acquisition of Macro-Actions by PbD reduced the driving time by about 16% compared to the case in which Macro-Actions were directly defined by a human subject. In addition, the learning time was also reduced by a faster convergence of the optimum policies.

• 한국환경복원기술학회지
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• 제11권1호
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• pp.72-84
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• 2008

Since enactment of the Baekdu-Mountain Range protection law in Dec. 31st 2003, great interest arose in recovery of the natural environment in the Baekdu-Mountain Range. Since the Baekdu-Mountain Range has formed boundaries between different regions and it is the mountain that crosses our country from East to West, there are so many roads that penetrate this area. Slopes made by the construction of roads have poor foundation for the growth of vegetation and it takes a long period to restore only with natural restoration force. For this reason, various methods of revegetation to restore the damages are implemented but until now, revegetation of domestic soil cutting slopes are mainly covered by foreign import grasses to stabilize and cover grounds early. As we depended upon foreign import grasses for slopes revegetation, the landscape did not match in harmony with surrounding vegetation and therefore, we could see that these foreign grasses are withered in 2~3 years after the revegetation works and slopes become barren again. However, currently, there are no applicable standards for designs of green hill, desirable revegetation methods for the hill areas, roads and recovery models. Therefore, in this study, we investigated the status of revegetation plants and revegetation methods for the hill areas of the Baekdu-Mountain Range (azimuth, degree of tilt, and tilted places). Based on this, we attempted to find the desirable recovery models for the hill areas of the Baekdu-Mountain Range.

• 터널과지하공간
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• 제22권4호
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• pp.284-295
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• 2012

본 연구에서는 암석 절삭 장비의 마모에 직접적인 영향을 주는 인자인 암석의 마모도(abrasiveness) 측정에 관한 연구를 수행하였다. 몇 가지 방법 중 세르샤 마모 시험(Cerchar abrasiveness test)을 통하여 암석의 마모도에 영향을 미치는 인자를 확인하고 효율적인 시험을 수행하기 위한 조건들을 연구하였다. 국내 19종 암석에 대한 시험 결과를 통하여, 세르샤 마모 지수(CAI, Cerchar Abrasiveness Index)에 영향을 미치는 암석의 역학적 물성(단축압축강도, 간접인장강도, 탄성계수, 포아송비, 공극률, 쇼어경도)과의 상관관계를 찾아보았고 X선 회절 분석을 통하여 암석의 구성 광물 중 마모도에 가장 큰 영향을 미치는 석영 함량, 등가 석영 함량과의 관계도 확인하였다. 그 결과로 암석의 입자 결합 특성보다 광물의 특성이 CAI에 영향을 더 미치는 것으로 관찰되었고, 단축압축강도와 등가 석영함량의 함수로 CAI를 예측하는 모델을 제시하였으며 핀의 경도가 커질수록 CAI값이 선형적으로 작아짐을 확인하였다. 수치해석적 연구를 통해 세르샤 마모 시험을 모사한 결과 초기 긁힘 거리에서 대부분의 마모가 발생함을 확인하였고 하중이 증가할수록 CAI값이 증가함을 확인하였다.

• 동남아시아연구
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• 제24권2호
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• pp.35-79
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• 2014

This study examines the measures for the activation and the growth of intra-regional trade in Southeast Asia taking a look at the four dimensions of tariff rates, non-tariff barriers, trade facilitations, and trade infrastructures. Utilizing a gravity model, we performed empirical analysis and discussed the policy implications with the priorities to implement. To expand the intra-regional trade in Southeast Asia it would be necessary to enhance the level of trade facilitations and provide trade infrastructures, such as ports and airports as well as cutting the tariff rates and eliminating the non-trade barriers. In particular, in the case of exports of ASEAN6 to ASEAN6 the infrastructure is the important factor. Also, in the case of the exports of ASEAN6 to CLMV(Cambodia, Laos, Myanmar, and Vietnam), it is expected that eliminating non-tariff barriers and enhancing trade facilitations may play important roles in the progress of intra-regional trade. These results may provide the important implications for Southeast Asian countries, which are trying to promote intra-regional trade ahead of the constitution of ASEAN Economic Community by 2015. Southeast Asian countries could be evaluated to achieve a certain level of trade liberalization and economic integration through the formation of AFTA. But in order for Southeast Asia to develop to advanced economic integrated region it requires mutual cooperations and policy harmonizations among regional countries. Also, for the elimination of non-tariff barriers, promoting trade facilitations, and providing infrastructures, the administrative, legal, and institutional measures would have to be fulfilled in advance. In addition, capital investment for constructing infrastructures would be necessary to realize the intra-regional trade expansion. However, to achieve the goal, it would require a large capital investment and highly mandated policy considerations and harmonizations among Southeast Asian countries in terms of further trade liberalization and economic integration.

• 한국기계가공학회지
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• 제18권9호
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• pp.29-35
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• 2019

The structure of the machinery industry due to the 4th industrial revolution is changing from precision and durability to intelligent and smart machinery through sensing and interconnection(IoT). There is a growing need for research on prognostics and health management(PHM) that can prevent abnormalities in processing machines and accurately predict and diagnose conditions. PHM is a technology that monitors the condition of a mechanical system, diagnoses signs of failure, and predicts the remaining life of the object. In this study, the vibration generated during machining is measured and a classification algorithm for normal and fault signals is developed. Arbitrary fault signal is collected by changing the conditions of un stable supply cutting oil and fixing jig. The signal processing is performed to apply the measured signal to the learning model. The sampling rate is changed for high speed operation and performed machine learning using raw signal without FFT. The fault classification algorithm for 1D convolution neural network composed of 2 convolution layers is developed.