• ETRI Journal
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• 제41권6호
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• pp.731-738
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• 2019

We proposed a novel electromagnetic band-gap (EBG) cell-embedded antenna structure for reducing the interference that radiates at the antenna edge in wireless access in vehicular environment (WAVE) communication systems for vehicle-to-everything communications. To suppress the radiation of surface waves from the ground plane and vehicle, EBG cells were inserted between micropatch arrays. A simulation was also performed to determine the optimum EBG cell structure located above the ground plane in a conformal linear microstrip patch array antenna. The characteristics such as return loss, peak gain, and radiation patterns obtained using the fabricated EBG cell-embedded antenna were superior to those obtained without the EBG cells. A return loss of 35.14 dB, peak gain of 10.15 dBi at 80°, and improvement of 2.037 dB max at the field of view in the radiation beam patterns were obtained using the proposed WAVE antenna.

• Journal of International Society for Simulation Surgery
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• 제3권1호
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• pp.1-8
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• 2016

In the field of Radiology, the Computer Aided Diagnosis is the technology which gives valuable information for surgical purpose. For its importance, several computer vison methods are processed to obtain useful information of images acquired from the imaging devices such as X-ray, Magnetic Resonance Imaging (MRI) and Computed Tomography (CT). These methods, called pattern recognition, extract features from images and feed them to some machine learning algorithm to find out meaningful patterns. Then the learned machine is then used for exploring patterns from unseen images. The radiologist can therefore easily find the information used for surgical planning or diagnosis of a patient through the Computer Aided Diagnosis. In this paper, we present a review on three widely-used methods applied to Computer Aided Diagnosis. The first one is the image processing methods which enhance meaningful information such as edge and remove the noise. Based on the improved image quality, we explain the second method called segmentation which separates the image into a set of regions. The separated regions such as bone, tissue, organs are then delivered to machine learning algorithms to extract representative information. We expect that this paper gives readers basic knowledges of the Computer Aided Diagnosis and intuition about computer vision methods applied in this area.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권9호
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• pp.2982-3003
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• 2014

With the explosive deployment of the wireless communications technology, the increased QoS requirement has sparked keen interest in network planning and optimization. As the major players in wireless network optimization, the BS's resource utilization and mobile user's QoS can be improved a lot by the load-balancing technology. In this paper, we propose a load-balancing strategy that uses Coordinated Multiple Points (CoMP) technology among the Base Stations (BS) to effectively extend network coverage and increase edge users signal quality. To use universally, different patterns of load-balancing based on CoMP are modeled and discussed. We define two QoS metrics to be guaranteed during CoMP load balancing: call blocking rate and efficient throughput. The closed-form expressions for these two QoS metrics are derived. The load-balancing capacity and QoS performances with different CoMP patterns are evaluated and analyzed in low-dense and high-dense traffic system. The numerical results present the reasonable CoMP load balancing pattern choice with guaranteed QoS in each system.

• Current Optics and Photonics
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• 제2권2호
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• pp.153-164
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• 2018

In semiconductor manufacturing, critical dimensions indicate the features of patterns formed by the semiconductor process. The purpose of measuring critical dimensions is to confirm whether patterns are made as intended. The deposition process for an organic light emitting diode (OLED) forms a luminous organic layer on the thin-film transistor electrode. The position of this organic layer greatly affects the luminescent performance of an OLED. Thus, a system for measuring the position of the organic layer from outside of the vacuum chamber in real-time is desired for monitoring the deposition process. Typically, imaging from large stand-off distances results in low spatial resolution because of diffraction blur, and it is difficult to attain an adequate industrial-level measurement. The proposed method offers a new superresolution single-image using a conversion formula between two different optical systems obtained by a deep learning technique. This formula converts an image measured at long distance and with low-resolution optics into one image as if it were measured with high-resolution optics. The performance of this method is evaluated with various samples in terms of spatial resolution and measurement performance.

• Current Optics and Photonics
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• 제2권2호
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• pp.140-146
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• 2018

In this paper, mesoscale optical surface structures are found to possess both geometric and wave optics features. The study reveals that geometric optic analysis cannot correctly predict the experimental results of light transmission or reflection by mesoscale optical structures, and that, for reliable analyses, a hybrid approach incorporating both geometric and wave optic theories should be employed. By analyzing the transmission patterns generated by the mesoscale periodic pyramid prism plates, we show that the wave optic feature is mainly ascribed to the edge diffraction effect and we estimate the relative contributions of the wave optic diffraction effect and the geometric refraction effect to the total scattering field distribution with respect to the relative dimension of the structures.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권3호
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• pp.216-221
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• 2009

Purpose: The retention of the basement membrane complex, which was the unique feature of the acellular dermal matrix ($AlloDerm^{(R)}$), plays an important role in the normal process of wound healing. The present study was aimed to compare the healing of the acellular dermal matrix according to the graft method in the rabbit ear. Materials and methods: Six mature rabbits weighing about 3.0 kg were used, $10\;{\times}\;5\;mm$ sized subcutaneous pockets were created between the ear skin and the underlying perichondrium. In the control group, the acellular dermal matrix was grafted with the basement membrane facing toward the perichondrium. On the contrary, the acellular dermal matrix was grafted with the basement membrane facing toward the skin side in the experimental group I. In the experimental group II, the acellular dermal matrix was grafted like rolled configuration with basement membrane side in. The grafted site was picked at 3, 7, and 21 days after the graft. Serial sections were processed by H-E stain and examined under light microscopy to assess the healing patterns. Results: There was no distinct volume loss in the gross examination, but resorption was observed from the edge of the acellular dermal matrix in the histological examination. The space of resorption was replaced by the newly formed fibrous tissues and vessels. The inflammatory cells were more increased at 7 days after the graft than the early days. However, inflammation was decreased at 21 days after the graft. Regardless of the graft direction, no differences were observed between the control and the experimental group I in the healing patterns. Conclusion: These results suggest that the acellular dermal matrix can be used simply and effectively without regard to the graft direction as a substitute of autogenous material for repairing soft tissue defect.

• 한국콘텐츠학회논문지
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• 제17권2호
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• pp.96-104
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• 2017

최근의 스마트 기기들은 사용자의 의도와 사용 맥락을 반영하는 지능형 에이전트의 형태로 발전하고 있으며, 기능을 더 쉽고 편리하게 활용할 수 있는 사용자 경험 설계가 경쟁력의 핵심이 되고 있다. 본 연구는 인간중심의 내추럴 인터랙션이 최적의 스마트TV 경험에 필수적이라는 전제하에 TV에 특화된 음성 인터랙션 방식을 탐구하고자 하였다. 사용자가 자연스러운 행태로 TV를 조작하는 모델을 구축하기 위하여 스마트TV의 주요 기능을 지능형 에이전트에 명령하도록 하였고 대화 패턴을 수집하였다. 수집된 문장은 CfA 모델에 대입하여 기능 실행을 위한 반응 별로 분류하였다. 분류된 5가지 대화 패턴은 스마트TV가 실행하는 기능 특성에 따라 '기능 실행'과 '정보 검색'으로 나눌 수 있었다. 사용자와 TV간의 음성 상호작용에서 모호한 요청의 경우 재확인을 위한 CfC1이 발생하고, 복합 의도나 조건부 요청에 대한 대응이 필요한 경우는 CfC2가 발생한다는 부분도 확인하였다. 본 연구의 결론은 스마트TV에서의 음성 UI 설계에서 Simple Request Type이 가장 효율적 모델이라는 점과 대화형 인터랙션은 가능한 사용자의 모호한 요청을 구체화하기 위한 단계에서만 활용되는 것이 적합하다는 것이다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.34-38
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• 1995

Using a 3-D finite element method (FEM), the biomechanical characteristics of a threaded truncated acetabular component and a porous coated hemispherical acetabular component were studied. The Von-Mises stress/strain patterns in the acetabulum reconstructed with these two different types of cementless acetabular cups were investigated. The geometry and dimensions of human hemi-pelvis used in the present shape modeling for finite element analysis were scanned with a 3-D laser scanner(TDS-9000, Cyberware, USA). The scanned data was numerically handled with a shape modelling software 'Pro-Engineer'. Using 19836, 16853 tetrahedral elements, respectively, the stress and displacement field of the acetabulum reconstructed with the two different types of the acetabular components were computed. While the hemi-sphere component was found to show a relatively similar stress/strain patterns to those in the normal hip, the results with the threaded cup showed a considerably different patterns from those in the normal condition. Several regions in cancellous bone near the threads and the edge of the truncated cup was found to be overstressed, especially in the superior-lateral part of the acetabulum. It was postulated that the excessive reaming-out of subchondral bone layer when the truncated cup was used can cause the presence of these overstressed regions of cancellous bone. This theoretical prediction for the implanted acetabulum appeared to consistent with the pathological observation of proximal/medial migration of the threaded truncated acetabular prostheses in the previous publications.

• 한국기계가공학회지
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• 제13권2호
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• pp.64-72
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• 2014

In the past, prism patterns have been linear triangular shapeswith a $90^{\circ}$ angle; however, new micro prism patterns having acute angles or obtuse angles have recently been the subject of demandin the display, lighting and photovoltaic industries. Micro-cutting experiments for micro-prism patterns having $60^{\circ}$, $90^{\circ}$, and $120^{\circ}$ angles on an electroplated Ni mold were performed and it was found in this study that the specific cutting resistance increased with a decrease in the tool angles (prism pattern angles). The cause of this variation had been thought to be the increase of the ploughing force due to tip rounding and the friction force due to the edge effect. However, the depth of the cut was large enough that it was possible to neglect these effects. Therefore, this study introduced the concept of representative stress of indentation. The measured stress was varied according to the indentation depth eventhoughthetestedspecimenswereidentical ; the varied stress was termed the representative stress. According to indentation theory, the strain that the Ni mold experienced increased with a decrease in the tool angle. Based on the stress-strain relationship, higher strain means higher stress and higher specific cutting resistance. Therefore, the specific cutting resistance was higher at smaller tool angles that had higher strain and stress.

• 마이크로전자및패키징학회지
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• 제16권2호
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• pp.11-19
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• 2009

모아레 간섭계를 이용하여 와이어 본딩 플라스틱 볼 그리드 (WB-PBGA) 패키지의 열-기계적인 거동 특성을 연구하였다. 실시간 모아레 간섭계를 이용하여 각 온도단계 에서 변위분포를 나타내는 간섭무늬를 각각 얻고, 그로부터 굽힘변형 거동 및 솔더볼의 변형률에 대한 해석을 비교하여 수행하였다. 본 실험에서는 full grid와 perimeter with central connections 및 perimeter의 배열 형태를 갖는 세 가지 패키지를 사용하였으며, 이 배열 형태를 비교하여 굽힘변형 및 솔더볼의 평균변형률을 자세하게 해석하였다. 솔더볼의 유효변형률은 WB-PBGA-FG의 경우 칩 가장자리 바로 바깥쪽 솔더볼에서, WB-PBGA-P/C의 경우 가운데 연결 솔더볼의 가장 바깥 솔더볼에서, WB-PBGA-P의 경우는 칩과 가장 기까운 안쪽 솔더볼에서 최대값을 가지는 것으로 나타났다.