• Information and Communications Magazine
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• v.26 no.4
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• pp.3-11
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• 2009

과거 유선 통신 시장이 음성 위주에서 데이터 통신 위주로 급격하게 변화되었듯이, 무선 통신 환경 또한 음성 위주의 사업에서는 임계점에 다다르고 있다. 이런 상황에서 새로운 차세대 모바일 서비스에 대한 다양한 고민들이 등장하기 시작했고, "모바일 @@@ 2.0"과 같이 불리고 있다. 이처럼 "모바일 @@@ 2.0"과 같은 많은 유사한 용어들이 사용되고 있는데, 멀티미디어, 인터넷, 웹 표준 기술 중 어떤 기술에 보다 많은 비중을 두고, 강조를 하고 싶은가에 따라 이처럼 변형된 용어들이 탄생했다고 할 수 있다. 이런 용어적 차이와 혼동에도 불구하고, 모두 차세대 모바일 서비스 기술을 의미하고자 한다는 점에서는 동일하다고 할 수 있다. 이에 본고에서는 "모바일 2.0"이라는 대표 용어로 차세대 모바일 서비스를 통칭하며, 모바일 2.0 서비스 동향과 전망을 살피고 거시적 관점에서의 차세대 모바일 서비스의 발전 방향을 함께 살피고자 하였다.

• Journal of Korean Society of Steel Construction
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• v.8 no.4 s.29
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• pp.31-42
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• 1996

본 연구에서는 박벽 구조물의 기하학적 비선형 해석을 수행하기 위하여 개선된 하중 및 변위 증분의 조합법이 제시되었다. 제안된 알고리즘은 기존의 하중 및 변 변위 증분의 조합법 이 고정된 증분량을 갖는 점을 개선하여, 수렴정도에 따라 증분량을 변화시킴으로써, 여러개의 임계점을 갖는 비선형 거동을 보다 효율적으로 추적하도록 하였다. 또한 하중 및 변위 증분법을 전환점을 첫 단계의 기울기에 비례한 값으로 대체함으로써 사용자의 편리를 도모하였다. 트러스, 공간 뼈대, 아치, 쉘 구조물 등의 기하학적 비선형 해석 예제를 통하여, 본 연구에서 제시한 개선된 하중 및 변위 증분의 조합법의 적용성을 입증하였다.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.100-109
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• 2017

이번 연구에서 우리는 궤적 앙상블을 이용해 1 차원 Ising 모형의 동역학적 상전이를 관측했다. s 앙상블이라고도 불리는 궤적 앙상블은 활성도의 켤레 변수를 도입해 활성도에 편중을 두어 궤적을 추출한 앙상블이다. 평형상태에 있는 1 차원 Ising 모델에서는 외부 자기장이 존재하지 않을 때 상전이가 나타나지 않는다. 하지만 s 앙상블을 통해서 우리는 1 차원 Ising 모형에서 동역학적 상전이가 존재한다는 사실을 발견할 수 있었다. 이동역학적 상전이는 유한 크기 조정 법칙이 잘 적용되며 2 차원 Ising 모형과 같은 보편성 등급을 가진 것을 통해 두 상전이가 서로 연관되어 있다는 것을 알 수 있었다. 또한 열역학적 함수인 에너지와 동역학적 함수인 활성도 사이에 선형관계가 존재하는 점을 통해 동역학적 함수와 열역학적 함수 사이의 관계가 존재하는 것을 확인했다. 마지막으로 또 다른 열역학적인 함수인 자화도에 편중을 두었을 때 동역학적 상전이가 일어나는 임계점이 이동하는 것을 통해 에너지 외의 다른 열역학적 함수도 동역학적 함수와 연관된다는 것을 알아냈다.

• Journal of the Korean Orthopaedic Association
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• v.56 no.6
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• pp.498-503
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• 2021

Purpose: The aim of this study were to find ideal entry point of straight antegrade humeral intramedullary nail (SAHN) for the treatment of proximal humerus fracture in Korean and to analyze anatomical conformity using computed tomography. Materials and Methods: From May 2014 to October 2016, the study was conducted retrospectively on 74 Korean patients who had taken computed tomography on both normal and affected shoulder joint as result of shoulder injury. The mean age of the patients was 64.5 years (range, 22-95 years). Radiologic evaluation was done using multiplanar reconstruction technique of the computer tomography on normal proximal humerus. We located ideal entry point of SAHN as the point where humerus intramedullary center axis and humeral head meet. Distance between the entry point and local anatomical landmark was measured. We defined the critical distance as the distance between entry point and the most medial point of the supraspinatus attachment site. For adequate fixation and avoidance of injury to rotator cuff, critical distance should be over 8 mm according to Euler, and we defined the critical type when it is less than 8 mm. Critical distance, sex, age, height, body weight, body mass index was evaluated for the statistical significance. Results: The ideal entry point was as follows: the mean anteroposterior distance, the sagittal distance to the lateral margin of bicipital groove, was 11.5 mm and the mean mediolateral distance, the coronal distance to the lateral margin of grater tuberosity, was 20.5 mm. The mean critical distance, distance from the entry point to the just medial to insertion of the supraspinatus tendon, was 8.0 mm. Critical type with critical distance less than 8 mm was found in 41 in 74 patients (55.4%). Conclusion: The ideal entry point of SAHN in Korean was located on 11.5 mm posteriorly from the lateral margin of bicipital groove and 20.5 mm medially from lateral margin of greater tuberosity. More than half of the cases were critical type. Since critical type can possibly cause rotate cuff injury during nail insertion on entry point, surgeon should consider anatomical variance before choosing surgical option.

• Clean Technology
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• v.17 no.1
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• pp.19-24
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• 2011

The bubble point pressures of binary mixtures of carbon dioxide ($CO_2$) and N,N-dimethylformamide (DMF) were measured by using a high-pressure experimental apparatus equipped with a variable-volume view cell, at various $CO_2$ compositions in the range of temperatures above the critical temperature of $CO_2$ and below the critical temperature of DMF. The experimental bubble point pressure data were correlated with the Peng-Robinson equation of state (PR-EOS) to estimate the corresponding dew point compositions at equilibrium with the bubble point compositions. The experimentally measured bubble point pressures gave good agreement with those calculated by the PR-EOS. The variable-volume view cell equipment was verified to be an easy and quick way to measure the bubble point pressures of high-pressure compressible fluid mixtures.

• The Journal of the Acoustical Society of Korea
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• v.37 no.1
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• pp.1-11
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• 2018

Sound propagation in shallow water changes from spherical spreading to cylindrical spreading, depending on boundary conditions, and this point is defined as a transition point of the sound propagation condition. Theoretically, the transition point can be estimated using the transmission loss as a function of source-receiver range. In this paper, the transmission loss curve in a Pekeris waveguide is predicted using a parabolic-equation based acoustic propagation model and using this transmission loss curve, the range from the source of the transition point is estimated, which is compared to the critical distance calculated using the sound speed ratio of water to sediment. In addition, the effects of the sound speed profile and source depth change on the transition point are investigated. Finally, the transition point is estimated using the transmission loss data measured during the period of the SAVEX15 (Shallow Water Acoustic Variability EXperiment 2015) conducted 65 km southwest of Jeju Island in May 2015, and it is compared to the ocean environmental parameters to understand the properties of sound propagation in the experimental area.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.11-20
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• 2006

This paper describes the technique which utilizes a fuzzy neural network to sketch feature extraction in digital images. We configure an artificial neural network and make it learn fuzzy membership functions to decide a local threshold applying to sketch feature extraction. To do this. we put the learning data which is membership functions generated based on optimal feature map of a few standard images into the artificial neural network. The proposed technique extracts sketch features in an images very effectively and rapidly because the input fuzzy variable have some desirable characteristics for feature extraction such as dependency of local intensity and excellent performance and the proposed fuzzy neural network is learned from their membership functions, We show that the fuzzy neural network has a good performance in extracting sketch features without human intervention.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.1-9
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• 2002

There is the high possibility of crack initiation from mechanical joints, which are widely used in aircraft fuselages, due to the development of stress concentration and contact pressure. In this paper, the mixed-mode stress intensity factors at the surface and deepest points of an inclined quarter elliptical corner crack in mechanical joints are analyzed by the weight function method. The coefficients included in the weight function are obtained by finite element analyses for reference loadings. Critical angle at which mode I stress intensity factor becomes maximum is determined by analyzing the variation of stress intensity factors along incline angle of crack and the effects of the amount of clearance and crack depth on the critical angle are investigated.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.1-6
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• 2017

This paper focuses on the development of a system that improves the convenience of foreign language learning and enhaces the learning ability of the target language through the use of IT devices. In addition to the basic grammar, the importance of pronunciation and intonation have somewhat crucial effect in everyday communication. Pronunciation and intonation of English are different according to the basic characteristics of a native language and these differences often cause problems in communication. The proposed system distinguishes acceptability in English communication process and requests the correction in realtime. The proposed system minimizes system intervention by collecting various voice signals of foreign language learners and setting that can be considered as acceptable threshold points. As a result, the learner can increase the learning efficiency with minimal interruption of the utterance caused by unnecessary system intervention.

• Information Systems Review
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• v.9 no.2
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• pp.85-108
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• 2007

Currently, most of big IT companies attempt to penetrate into Internet portal industry aggressively in order to expand their channels(sale, distribution, marketing, R&D, and so on) and to acquire competitive advantages. Existing Internet portals also have become larger and more complex with continuous developments. Therefore, it is necessary to acquire competitive contents to survive the extreme competition and to satisfy diverse needs of customers. In this paper, we have done qualitative analyses on the cases of domestic and foreign major Internet portals which have acquired contents through of M&A and strategic alliances. In our analyses, we identify five factors crucial to the successes and failures of Internet portals. From the analyses, we find that the acquisition of UCC based contents and subscribers over the critical mass point are the two most important factors that should be simultaneously satisfied for the successful M&As. Additional analyses suggest how to acquire synergy effects from successful M&As.