• 한국산업정보학회논문지
• /
• 제18권1호
• /
• pp.11-17
• /
• 2013

A design method to achieve multiple band-rejection characteristics in a wideband circular slot antenna is presented. First, a wideband circular slot antenna fed by a coplanar waveguide is designed to operate in the frequency range between 2.3 and 11GHz, which covers WLAN, WiBro, WiMAX, and UWB frequency bands. Next, resonant frequency variations of rejection bands are examined with respect to different slot locations and lengths when slots are inserted on the ground conductor and the circular patch of the antenna. When arc-shaped slots are placed close to the circular transition from a feeding part, multiple notch bands are obtained. In this case, a half of the guided wavelength of the first notch band corresponds to the slot length and other notch bands are integer-multiple of the first band. Single notch band can be obtained when the slot is located off the transition part. Based on this study, a wideband circular slot antenna with five band-rejection frequency bands at 2.45, 3.5, 4.9, 7.35, and 9.8GHz is designed and fabricated. The first arc-shaped slots are located in the ground conductor close to the circular transition from a feeding part to generate notch bands at 2.45, 4.9, 7.35, and 9.8GHz, while the second slot for 3.73 GHz is placed on top side in the circular patch. The proposed design method is validated by good agreement between the simulated and measured results.

• 한국군사과학기술학회지
• /
• 제17권2호
• /
• pp.223-234
• /
• 2014

This paper proposes a flexible and highly reusable modeling methodology for a next-generation combat entity which enables joint analysis of performance/engagement effectiveness. According to the scope of the proposed work, the paper is divided into two parts; Part 1 focuses on a conceptual model design, whereas Part 2 proposes detailed model specification and implementation. In Part 1, we, first, classify the combat entity model as combat logic and battlefield function sub-models for joint analysis. Based on the sub-models, we propose two dimensional model partition method, which creates six groups of a single combat entity model by two dimensions: three-activity and two-abstraction. This grouping enables us to reconfigure the combat entity model by sharing the same interface within the group, and the same interface becomes the fundamental basis of the flexible model composition. Furthermore, the proposed method provides a model structure that effectively reflects the real world and maximizes the multi-level reusability of a combat entity model. As a case study, we construct a model design for anti-surface ship warfare. The case study proves enhancement of model reusability in the process of scenario expansion from pattern running to wire guided torpedo operations.

• 한국항공우주학회지
• /
• 제46권11호
• /
• pp.911-920
• /
• 2018

본 연구에서는 스트랩 다운 영상 탐색기를 활용한 유도무기와 목표물 사이의 관측각을 효과적으로 추적할 수 있는 연구를 수행하였고 이를 시각적으로 시뮬레이션 가능한 테스트 베드를 구축하였다. 영상 정보를 이용하여 목표물 추적을 위한 Lucas Kanade의 Optical flow 알고리즘과 같은 희박 특징점 추적 알고리즘 구현 시 고성능의 특징점 분포를 유지시키는 법을 기술하였으며, 특징점 추적 문제를 특징점 관리의 개념으로 확장하여 연구하였다. 이를 구현하기 위해 Unity3D 엔진을 이용하여 시각 환경을 구성하고 OpenCV를 이용하여 영상 처리 시뮬레이션을 개발하였다. 상호-시뮬레이션을 위해 매틀랩(Matlab) 시뮬링크(Simulink)로 동적 시스템 모델링을 하였고, Unity3D를 이용한 시각 환경을 구성, OpenCV를 이용한 컴퓨터 비전 작업을 수행하였다.

• 한국융합학회논문지
• /
• 제12권2호
• /
• pp.29-34
• /
• 2021

본 논문에서는 중심에 동공을 갖는 원통형태 광결정 도파로가 제안되어지고, 이 전송로의 도파 특성에 대한 분석이 수행되어진다. 여기서 동공은 일반적인 공기이거나 임의의 액체나 고체 물질들에 의한 저지수 유전체로써 형성되게 된다. 베셀 함수를 이용한 분석적 방법으로 전자장에 대한 엄밀한 해를 구하기 위하여, 행렬 기법이 고유치 방정식의 유도에 사용되고, 실효 굴절률, 분산, 전자장 분포 등의 기본 모드의 중요한 전송 성질들이 조사된다. 또한 분석 결과 정확도의 검증을 위하여 엄밀한 완전 벡터 유한 차분법을 적용해보고, 광결정 도파로의 설계와 제조 상의 문제를 해결하는데 용이하게 활용하고자 한다. 설계된 중심-동공 광도파관의 실효 모드 면적이 2.6056 ㎛2에서 5.9673 ㎛2까지 동작 파장에 따라 다양하게 변하며, 일반적으로 광도파로의 중심으로부터 바깥쪽으로 원통형의 층수가 적을수록 그리고 굴절률 n1이 약간 큰 저지수일수록 실효 면적은 작아지므로, 비선형 소자 응용의 관점에서 훨씬 더 최적화된 결과를 나타낸다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제16권1호
• /
• pp.16-37
• /
• 2022

Accurate liver segment segmentation based on radiological images is indispensable for the preoperative analysis of liver tumor resection surgery. However, most of the existing segmentation methods are not feasible to be used directly for this task due to the challenge of exact edge prediction with some tiny and slender vessels as its clinical segmentation criterion. To address this problem, we propose a novel deep learning based segmentation model, called Boundary-Aware Dual Attention Liver Segment Segmentation Model (BADA). This model can improve the segmentation accuracy of liver segments with enhancing the edges including the vessels serving as segment boundaries. In our model, the dual gated attention is proposed, which composes of a spatial attention module and a semantic attention module. The spatial attention module enhances the weights of key edge regions by concerning about the salient intensity changes, while the semantic attention amplifies the contribution of filters that can extract more discriminative feature information by weighting the significant convolution channels. Simultaneously, we build a dataset of liver segments including 59 clinic cases with dynamically contrast enhanced MRI(Magnetic Resonance Imaging) of portal vein stage, which annotated by several professional radiologists. Comparing with several state-of-the-art methods and baseline segmentation methods, we achieve the best results on this clinic liver segment segmentation dataset, where Mean Dice, Mean Sensitivity and Mean Positive Predicted Value reach 89.01%, 87.71% and 90.67%, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제17권8호
• /
• pp.2140-2156
• /
• 2023

The Wireless Sensor Network (WSN), is constructed out of teeny-tiny sensor nodes that are very low-cost, have a low impact on the environment in terms of the amount of power they consume, and are able to successfully transmit data to the base station. The primary challenges that are presented by WSN are those that are posed by the distance between nodes, the amount of energy that is consumed, and the delay in time. The sensor node's source of power supply is a battery, and this particular battery is not capable of being recharged. In this scenario, the amount of energy that is consumed rises in direct proportion to the distance that separates the nodes. Here, we present a Hybrid Firefly Glow-Worm Swarm Optimization (HF-GSO) guided routing strategy for preserving WSNs' low power footprint. An efficient fitness function based on firefly optimization is used to select the Cluster Head (CH) in this procedure. It aids in minimising power consumption and the occurrence of dead sensor nodes. After a cluster head (CH) has been chosen, the Glow-Worm Swarm Optimization (GSO) algorithm is used to figure out the best path for sending data to the sink node. Power consumption, throughput, packet delivery ratio, and network lifetime are just some of the metrics measured and compared between the proposed method and methods that are conceptually similar to those already in use. Simulation results showed that the proposed method significantly reduced energy consumption compared to the state-of-the-art methods, while simultaneously increasing the number of functioning sensor nodes by 2.4%. Proposed method produces superior outcomes compared to alternative optimization-based methods.

• 한국정보교육학회:학술대회논문집
• /
• 한국정보교육학회 2021년도 학술논문집
• /
• pp.239-245
• /
• 2021

한국교육방송공사에서 초등학생을 대상으로 4주간 실시한 학습 멘토링의 교육적 효과를 분석하기 위해, 학습 멘토링에 참여한 27명의 학생을 대상으로 자기주도적 학습능력과 정서적 안정감의 변화를 사전사후 검사를 통해 분석하였다. 그 결과, 학생들의 자기주도적 학습능력과 정서적 안정감이 모두 향상된 것으로 파악되었다. 또한, 학생들은 학습을 지도해준 멘토에 대한 만족도가 높게 나타났다. 따라서 원격 수업 상황에서 소외계층 학생들의 학습 격차를 줄이려면, EBS 학습 멘토링 사업을 지속적으로 추진하고, 멘토링 기간과 멘토링에 참여하는 학생과 교사의 수도 크게 증가시켜야 한다.

• 한국의류산업학회지
• /
• 제25권5호
• /
• pp.560-567
• /
• 2023

This study aims to rediscover the industrial value of a borderless service in the hyper-connected era by producing fashion content at the forefront of the cultural industry as XR content and contributing to developing fashion content for edutech. The research method employed design aesthetic theory, while the empirical proposal utilized scientific knowledge information to build a framework for 3D convergence content. The characteristics of fashion content exhibitions that apply the neumorphism technique are as follows: The first is a virtual space that produces clothing culture by type. Africa, where dyeing and crafts are developed, selects a product-oriented exhibition type; Asia, where weaving and textiles are excellent, selects a random movement type; and Europe, where the evolution of clothing design over time is evident, selects a guided movement type to create a three-dimensional fashion edutech. The goal was to produce content. The second is creative reproducibility, which combines a new fashion design that embraces the aura of the original with a trendy sense. The realistic folk costume style of the original allowed for its implementation in the AR exhibition space using historical traditional style techniques such as weaving and textiles. The third is building organic, modular content. By designing and then saving/editing/arranging the basic VP zone for each style, learners and instructors can freely edit the content for each fashion class topic and create various presentations to ensure that it functions as non-face-to-face edutech content around the world.

• Journal of Periodontal and Implant Science
• /
• 제53권5호
• /
• pp.388-401
• /
• 2023

Purpose: This study investigated the accuracy of free-hand implant surgery performed by an experienced operator compared to static guided implant surgery performed by an inexperienced operator on an anterior maxillary dental model arch. Methods: A maxillary dental model with missing teeth (No. 11, 22, and 23) was used for this in vitro study. An intraoral scan was performed on the model, with the resulting digital impression exported as a stereolithography file. Next, a cone-beam computed tomography (CBCT) scan was performed, with the resulting image exported as a Digital Imaging and Communications in Medicine file. Both files were imported into the RealGUIDE 5.0 dental implant planning software. Active Bio implants were selected to place into the model. A single stereolithographic 3-dimensional surgical guide was printed for all cases. Ten clinicians, divided into 2 groups, placed a total of 60 implants in 20 acrylic resin maxillary models. Due to the small sample size, the Mann-Whitney test was used to analyze mean values in the 2 groups. Statistical analyses were performed using SAS version 9.4. Results: The accuracy of implant placement using a surgical guide was significantly higher than that of free-hand implantation. The mean difference between the planned and actual implant positions at the apex was 0.68 mm for the experienced group using the free-hand technique and 0.14 mm for the non-experienced group using the surgical guide technique (P=0.019). At the top of the implant, the mean difference was 1.04 mm for the experienced group using the free-hand technique and 0.52 mm for the non-experienced group using the surgical guide technique (P=0.044). Conclusions: The data from this study will provide valuable insights for future studies, since in vitro studies should be conducted extensively in advance of retrospective or prospective studies to avoid burdening patients unnecessarily.

• 대한치과보철학회지
• /
• 제62권3호
• /
• pp.243-252
• /
• 2024

상하악 완전 무치악 환자에서 임플란트 지지 고정성 최종 보철물을 제작할 때 환자의 수직 고경, 악간관계, 구강내에 식립된 임플란트와 임플란트에 연결된 지대주, 그리고 잇몸 형태에 관한 정확한 정보의 체득이 중요하다. 본 증례에서는 임시 보철물을 통해서 이러한 정보들을 채득하여 최종 보철물을 제작하였다. 임시 보철물을 구강 밖에서 스캔하여 스캔의 효율성을 높였고, 스캔 때 임시 보철물의 양측 후방 부위를 연결하는 스캔지그를 사용하여 스캔의 정밀도를 향상시켰다. 본 증례에서는 이와 같은 디지털 기술을 활용하여 심미적, 기능적으로 만족할 만한 임상적 결과를 얻었기에 이를 보고하는 바이다.