• Geomechanics and Engineering
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• 제8권4호
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• pp.495-510
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• 2015

The applications of water jet cutting (WJC) in coal mine have progressed slowly. In this paper, we analyzed the possibility and reasonableness of WJC application to pressure relief in hard coal seam, simulated the distributive characteristics of stress and energy fields suffered by hard coal roadway wallrock and the internal relationships of the fields to the instability due to WJC (including horizontal radial slot and vertical annular slot) on roadway wallrock. The results showed that: (1) WJC can unload hard coal seam effectively by inducing stress release and energy dissipation in coal mass near its slots; its annular slots also can block or weaken stress and energy transfer in coal mass; (2) the two slots may cause "the beam structure" and "the small pillar skeleton", and "the layered energy reservoir structure", respectively, which lead to the increase in stress concentration and energy accumulation in coal element mass near the slots; (3) the reasonable design and optimization of slots' positions and their combination not only can significantly reduce the scope of stress concentration and energy accumulation, but also destroy coal mass structure on a larger scale to force stress to transfer deeper coal mass.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.3-8
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• 2006

The application of three-dimensional (3-D) CAD has been popularized for design and production and digital manufacturing has been spreading in many industrial fields. By simulation of the production process using 3-D digital models, which are the core of CIM (Computer Integrated Manufacturing) system, the efficiency and safety of production are improved at each stage of work, and optimization of manufacturing can be achieved. This paper firstly describes the concept of "simulation based production" in shipbuilding and also digital manufacturing; the 3-D CAD system is indispensable for effective simulation because ship structure is three dimensionally complex. By simulation, "computer optimized manufacturing" can be possible. The most effective fields of simulation in shipbuilding are in jobs where many parties have to cooperate, while existing two-dimensional drawings are hardly observed the whole structures due to interference between structures or equipment of complex shape. In this paper some examples of the successful application in IHIMU (IHI Marine United Inc.) are shown: assembly of a pipe unit, erection of a complex hull block, carriage of equipment, installation of a propeller, and access in an engine room.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권8호
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• pp.407-414
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• 2004

In this paper, a new gray scale expression method that divides the scan lines into multiple blocks is suggested. The proposed method can drive 16 sub-fields per 1 TV field in the panel with XGA ($1366{\times}768$) resolution. The on and off states of even subfields depend on the condition of odd subfields. The write address mode is used in the odd subfields, while the erase address mode is used in the even subfields. Because the ramp reset pulse is applied every 2 sub-fields, both the contrast ratio and the dynamic voltage margin are sufficiently obtained in comparison with previous AWD (Address While Display) methods. In realizing 16 subfields, shortening the scan time in the erase address period was important. The X bias voltage in the erase address period affected the minimum address voltage but did not the delay time of the address discharge. The delay time of the address discharge was affected by the address voltage and the time interval between the last sustain discharge and the scanning time. We also evaluated the dynamic false contour. New method shows an improved image quality in horizontal moving, but discontinuous lines were observed at the boundaries of each block in vertical moving

• International Journal of Internet, Broadcasting and Communication
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• 제13권3호
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• pp.124-129
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• 2021

As the 4th industrial era is in full swing, the public's interest in related technologies such as artificial intelligence, big data, and block chain is increasing. As artificial intelligence technology is used in various industrial fields, the need for research methods incorporating artificial intelligence technology in related fields is also increasing. Evidence collection among digital forensic investigation techniques is a very important procedure in the investigation process that needs to prove a specific person's suspicions. However, there may be cases in which evidence is damaged due to intentional damage to evidence or other physical reasons, and there is a limit to the collection of evidence in this situation. Therefore, this paper we intends to propose an artificial intelligence-based evidence collection system that analyzes numerous image files reported by citizens in real time to visually check the location, user information, and shooting time of the image files. When this system is applied, it is expected that the evidence expected data collected in real time can be actually used as evidence, and it is also expected that the risk area analysis will be possible through big data analysis.

• Radiation Oncology Journal
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• 제12권2호
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• pp.253-262
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• 1994

The patterns of the conventional radiation treatment fields and their shielding blocks are analysed to determine the optimal dimension of the MultiLeaf Collimator (MLC) which is considered as an essential tool for conformal therapy. Total 1109 radiation fields from 303 patients (203 from Asan Medical center, 50 from Baek Hosp and 50 from Hanyang Univ. Hosp.) were analysed for this study. Weighted case selection treatment site (from The Korean Society of Therapeutic Radiology 1993). Ninety one percent of total fields have shielding blocks. Y axis is defined as leaf movement direction and it is assumed that MLC is installed on the cranial-caudal direction. The length of X axis were distributed from 4cm to 40cm (less than 21cm for $95\%$ of cases), and Y axis from 5cm to 38cm (less than 22cm for $95\%$ of cases). The shielding blocks extended to less than 6cm from center of the field for $95\%$ of the cases. Start length for ninety five percent of block is less than 10cm for X axis and 11cm for Y axis. Seventy six percent of shielding blocks could be placed by either X or Y axis direction, $7.9\%$ only by Y axis, $5.1\%$ only by X axis and It is reasonable to install MLC for Y direction. Ninety five percent of patients can be treated with coplanar rotation therapy without changing the collimator angle. Eleven percent of cases of cases were impossible to replace with MLC. Futher study of shielding technique is needed for $11\%$ impossible cases. The treatment field dimension of MLC should be larger than $21cm{\times}22cm$. The MLC should be designed as a pair of 21 leaves with 1cm wide for an acceptable resolution and 17cm long to enable the leaf to overtravel at least 6cm from the treatment field center.

• 한국정보처리학회논문지
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• 제6권11호
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• pp.3165-3177
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• 1999

With the recent outstanding advance in computer software and hardware, a number of researches to enhance the manufacturing speed and the process accuracy has been undertaken in many fields of textile industry. Frequently issued problems of automatic recognition of textile wrinkles in a grey scale image are as follows. First, changes in grey level intensity of wrinkles are so minute. Second, as both colors and patterns in a grey scale image appear in grey level intensity, it is difficult to sort out the wrinkle information only. Third, it is also difficult to distinguish grey level intensity changed by wrinkles from those by uneven illumination. This paper suggests a method of automatic recognition of textile wrinkles that can solve above problems concerned with wrinkles, which can be raised in a manufacturing process as one of errors. In this paper, we first make the outline of wrinkles distinctly, apply the block matching algorithm used in motion estimation, and then estimate block locations of target images corresponding to blocks of standard images with the assumption that wrinkles are kind of textile distortions caused by directional forces. We plot a "wrinkle map" considering distances between wrinkles as depths of wrinkles. But because mismatch can occur by different illumination intensity and changes in tensions and directions of the force, there are also undesirable patterns in the map. Post processing is needed to filter them out and get wrinkles information only. We use average grey level intensity of wrinkle map to recognize wrinkles. When it comes to textile with colors and patterns, previous researches on wrinkles in grey scale image hasn't been successful. But we make it possible by considering wrinkles as distortion.istortion.

• 전자공학회논문지CI
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• 제47권1호
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• pp.1-14
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• 2010

3D 콘텐츠 산업 분야의 급격한 성장과 더불어, 3D 콘텐츠 인증 및 신뢰, 검색을 위한 콘텐츠 해싱 기술이 요구되어지고 있다. 그러나 영상 및 동영상과 같은 2D 콘텐츠 해싱에 비하여 3D 콘텐츠 해싱에 대한 연구가 아직까지 미비하다. 본 논문에서는 키 기반의 3D 표면 계수 분포를 이용한 강인한 3D 메쉬 모델 해싱 기법을 제안한다. 제안한 기법에서는 기본적인 Euclid 기하학 변환에 강인한 3D SSD와 표면 곡률의 평면계 기반의 블록 표면 계수를 특징 벡터로 사용하며, 이를 치환 키 및 랜덤 변수 키에 의하여 최종 이진 해쉬를 생성한다. 실험 결과로부터 제안한 해싱 기법은 다양한 기하학 및 위상학 공격에 강인하며, 모델 및 키별로 해쉬의 유일성을 확인하였다.

• 전자공학회논문지
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• 제50권5호
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• pp.287-294
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• 2013

이진 연결요소 라벨링은 영상처리와 컴퓨터비전 등의 영역에 널리 사용되는 기법 중의 하나이다. 지금까지 여러 가지 방법의 라벨링기법이 연구되어 왔는데 그 중에서 이중스캔 방법이 가장 효과가 있는 것으로 나타나고 있다. 이중스캔 방법에서는 전통적으로 화소단위로 스캐닝을 하면서 순차적으로 라벨링하는 방법을 사용했는데 최근에는 C. Grana et. al. 및 L. He et. al. 등이 제안한 복수의 인접화소를 묶은 블록을 기반으로 라벨링하는 방법이 가장 효율적인 것으로 인정받고 있다. 본 논문에서는 화소기반의 스캔마스크를 사용하면서 라벨링은 Grana의 블록을 기반으로 하는 새로운 라벨링 방법을 제안하고 있다. 실제 사용하는 영상들에 대해 실험한 결과 영상의 종류에 따라 제안된 방법이 현재 가장 효율이 좋은 He의 방법에 비해 평균 3.9%에서 22.4%까지 성능의 향상이 있는 것으로 나타났다.

• 전기전자학회논문지
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• 제28권3호
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• pp.342-351
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• 2024

농업 분야에서 해충에 대한 효과적인 방제는 작물 생산성 향상에 필수적인 요소이다. 해충의 방제를 위해서는 해충의 종류, 발생 시기는 물론이며, 해충의 발생량에 대한 정보가 필요하다. 해충의 발생량을 파악하는 방법인 해충 카운팅 관련 선행 연구인, Mada-CenterNet은 변형 가능한 컨볼루션과 멀티스케일 어텐션 퓨전을 활용하여 해충 카운팅의 정확도를 향상시켰으며 해당 분야에서 가장 우수하다고 보고되고 있다. 본 연구에서는 Mada-CenterNet의 트랜스포머 구조인 멀티스케일 어텐션 대체하는 새로운 트랜스포머 구조인 듀얼 블록을 적용하였으며, 픽셀 경로와 시맨틱 경로의 교차 어텐션을 통해 더욱 정교한 특징 맵을 추출하였다. 실험 결과, 제안된 모델은 기존 Mada-CenterNet보다 해충 카운팅 정확도가 우수함과 동시에 폐색 문제와 해충의 몸체 손상, 다양한 모습으로 인한 탐지의 어려움을 효과적으로 완화하였다. 기존 해충 카운팅의 방법과 달리, 인력 및 시간 비용을 절감할 수 있다는 장점을 확보할 수 있으며 물체의 계수가 필요한 다른 농업 분야에도 활용이 가능할 것으로 기대된다.

• 한국의학물리학회지:의학물리
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• 제22권1호
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• pp.3-11
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• 2011

본 연구에서는 제작한 수직형 다엽 콜리메이터를 이용하여 방사선치료에 사용되는 Co-60 감마선 및 6 MV 엑스선의 조사면 크기와 모양을 결정하고 동일한 모양 및 크기의 조사면을 납차폐체로 결정하여 방사선 조사면 내 선량분포 특성을 상호 분석하여 수직형 다엽 콜리메이터의 방사선 조사면 크기 결정에 관한 유용성을 평가하였다. 이를 위해 이온전리함, 유리선량계, 방사선크로믹 필름을 사용하여 선량측정 실험을 수행하였다. Co-60 감마선과 6 MV 엑스선에 대하여 기준조사면의 이온전리함 측정결과 수직형 다엽 콜리메이터의 빔 중심축 선량값이 납차폐체의 선량값보다 각각 5.1%, 4.2% 높게 측정되었다. 그리고 Co-60 감마선에 대한 4개 조사면(기준 조사면, 원형, 삼각형, 십자형)의 유리선량계 측정 결과는 수직형 다엽 콜리메이터의 선량값이 납차폐체의 선량값보다 각각 2.2%, 7.8%, 7.2%, 4.0% 높게 측정되었고, 6 MV 엑스선에 대하여는 수직형 다엽 콜리메이터의 선량값이 납차폐체의 선량값보다 각각 6.7%, 6.2%, 3.8%, 6.2% 높게 측정되었다. 방사선크로믹 필름에서 차폐체의 선량분포곡선 중 최대선량의 80%에서 20%까지의 거리를 나타내는 반음영 크기는 모든 조사면에서 수직형 다엽 콜리메이터의 반음영 크기가 납차폐체보다 Co-60의 경우 2.0~3.5 mm, 6 MV 엑스선의 경우 0.5~1.0 mm 작게 나타났으며 이는 제작한 수직형 다엽 콜리메이터가 임상에 사용되었을 때 반음영의 크기를 납차폐체보다 줄일 수 있음으로써 치료 조사면적 결정시 차폐물의 반음영으로 생기는 방사선치료체적(Treatment Volume, TV)을 최소화시킬 수 있는 장점이 있으리라 판단된다. 아울러 2차원 및 3차원 방사선치료 시 본 다엽 콜리메이터를 이용하여 다양한 방사선치료 조사면을 간편하게 결정하여 사용할 수 있으리라 생각된다.