• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.916-917
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• 2008

In this paper, Switching damage of switches that is used to proposed power conversion system is reduced by soft switching way. dissipation by part resonance and my resonance stress for resonance of resonance circuit are decreased. Is acted by conversion system high effectiveness. Have following characteristic. Design snubber circuit that is used by switch protection in existent hard work rate Topology by resonant circuit for sogt switching, circuit structure was simple and control system is easy. Also, Can generate free output voltage by multi level Tuesday of output that use individuation Power Cell's Phase Shift PWM, and Low-end switching frequency the harmonic is few.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.87-93
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• 1999

To propose a useful modelling method for an actual muffler, the noise attenuation effects of muffler was investigated according to the flow condition and the hole shape of tubes. In this work, the finite element method was used to calculate the transmission loss of muffler, The noise attenuation characteristics of four different types of muffler in the hole shape of tubes were compared mutually to find a more simple equivalent model. Analytical results showed that the overall value of transmission loss increases and the peaks of transmission loss curve shift to the low frequency with mean flow for the given muffler, Also the noise attenuation characteristics of the equivalent model having the split holes is almost the same as those of the actual muffler having many circular holes.

• Proceedings of the Korean Society for Language and Information Conference
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• 2007.11a
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• pp.532-541
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• 2007

This paper investigates children's comprehension and production of demonstrative pronouns (DPs), 'zhege' (this) and 'nage' (that), in Mandarin Chinese. Subjects are children of ages three, four, five and six. Based on the results of the present experiment, children's developmental stages and the corresponding age grading are provided. Also, the present study incorporates a physical clue into the experiment. The result suggests that in the acquisition of deixis children rely highly on physical context to work out the meaning distinction. In addition, Piaget's egocentrism hypothesis and H. Clark's marking hypothesis are examined in the study. The result seems to support the egocentrism hypothesis. Subjects under the age of six do fail to shift the deictic center when they and the experimenter have a different perspective. As for the marking hypothesis, the study seems to challenge the hypothesis. The result shows that children actually performed better on the marked term 'zhege' than the unmarked member 'nage'.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.14-14
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• 2011

Graphene is known to possess excellent thermal properties, including high thermal conductivity, that make it a prime candidate material for heat management in ultra large scale integrated circuits. For device applications, the key parameters are the thermal expansion coefficient and the thermal conductivity. There has been no reliable experimental determination on the thermal expansion coefficient of graphene whereas the estimates of the thermal conductivity vary widely. In this work, we estimate the thermal expansion coefficient of graphene on silicon dioxide by measuring the temperature dependence of the Raman spectrum. The shift of the Raman peaks due to heating or cooling results from both the intrinsic temperature dependence of the Raman spectrum of graphene and the strain on the graphene film due to the thermal expansion mismatch with silicon dioxide. By carefully comparing the experimental data against theoretical calculations, it is possible to determine the thermal expansion coefficient. The thermal conductivity is measured by estimating the thermal profile of a graphene film suspended over a circular hole of the substrate.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.11-11
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• 2011

In this talk, I will discuss roles of pseudo vector and scalar potential in changing physical properties of graphene systems. First, graphene under small uniaxial strain is shown to be described by the generalized Weyl's Hamiltonian with inclusion of pseudo vector and scalar potential simultaneously [1]. Thus, strained graphene is predicted to exhibit velocity anisotropy as well as work function enhancement without any gap. Second, if homogeneous strains with different strengths are applied to each layer of bilayer graphene, transverse electric fields across the two layers can be generated without any external electronic sources, thereby opening an energy gap [2]. This phenomenon is made possible by generation of inequivalent pseudo scalar potentials in the two graphene layers. Third, when very tiny lateral interlayer shift occurs in bilayer graphene, the Fermi surfaces of the system are shown to undergo Lifshitz transition [3]. We will show that this unexpected hypersensitive electronic topological transition is caused by a unique interplay between the effective non-Abelian vector potential generated by sliding motions and Berry's phases associated with massless Dirac electrons.

• Journal of ILASS-Korea
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• v.12 no.4
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• pp.198-203
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• 2007

In the present work, surface wetting effect on spread-splash regime and transition criterion of the water and ethanol droplets impacting an unheated dry wall has been experimentally investigated. The droplet was directed on a polished STS plate and a glass slide, and the impinging behavior was visualized and recorded using a CCD camera. Droplet diameter and velocity approaching the wall were measured as well. The critical Sommerfeld number representing the spread-splash boundary for the ethanol droplet impinging on the substrates turned out to be smaller compared to that for the water droplet impinging on the substrates with the surface roughness condition remained unchanged. The shift of the transition boundary is considered to be due to the effect of the surface wettability represented by static contact angle and surface tension of droplet.

• Proceedings of the ESK Conference
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• 1997.10a
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• pp.186-195
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• 1997

본 연구에서는 교대근무를 시행하는 사업장을 조사아여 교대 분류방법에 의해 교대제의 명확한 분류 와 국내의 교대제 적용업체의 편성상의 문제점을 파악하고 개선안을 제시하며, 문제점과 편성의 성격에 따을 스트레스의 정도를 분석하고자 하였다. 교대제는 크게 비심야 교대제, 심야 교대제, 휴일이 있는 종일 교대제, 휴일이 없는 종일 교대제로 나누어 진다. 마산, 창원 지역의 교대제는 휴일이 있는 종일 교대제를 가장 많이 취하고 있었으며, 전반적인 문제점으로는 휴일이 없는 교대제가 존재하며, 야근 연 속 일수가 4일 이상으로 길고, 생체리듬의 길어지는 특성에맞지 않는 역순환이 존재하며 휴일이 없는 종 일 교대제에서 야간 근무에서 주간근무로 근무간격시간이 짧다는 여러 가지 문제점을 가지고 있다. 편성 상의 문제점과 성격에 의한 SACL의 분석에서장시간 근무하는 12시간 2교대 보다 8시간 정상 근무하는 3교대 의 스트레스가 낮고, 야근 연속일 수는 5일 이하인 경우의 스트레스가 제일 낮았고, 휴일은 있는 경우가 높았다. 연령별로는 40대에서 교대제 편성상에따른 프트레스 점수간 차이를 보였지만 다른 연령대에서는 차이를 보이지 않았다.

• Electronics and Telecommunications Trends
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• v.35 no.2
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• pp.1-16
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• 2020

"Artificial Intelligence+" is a key strategic direction that has garnered the attention of several global medical device manufacturers and internet companies. Large hospitals are actively involved in different types of medical AI research and cooperation projects. Medical AI is expected to create numerous opportunities and advancements in areas such as medical imaging, computer aided diagnostics and clinical decision support, new drug development, personal healthcare, pathology analysis, and genetic disease prediction. On the contrary, some studies on the limitations and problems in current conditions such as lack of clinical validation, difficulty in performance comparison, lack of interoperability, adversarial attacks, and computational manipulations are being published. Overall, the medical AI field is in a paradigm shift. Regarding international standardization, the work on the top 10 standardization issues is witnessing rapid progress and the competition for standard development has become fierce.

• Proceedings of the Korea Association of Information Systems Conference
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• 2005.12a
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• pp.463-470
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• 2005

In a rapidly changing business environment, the improvement of managerial techniques through IT utilization brings about remarkable increases in profitability and redesign of work process for better performances. IT innovation by electronic instruments such as ICT e-business provides accelerates forming inter-organizational information network and helps them benchmark the best practices of advanced organizations. A new shift of paradigm by e-business across all enterprises has turned the traditional aspects of inter-organizational competition and relationship into a form of collaboration. Collaboration enables business activities in parallel position among companies and facilitates cooperation between partner enterprises. Lately, the concept of 'Synchronization' is emerging beyond dimension of cooperation between networks, and the most concepts related to it are converging into 'Collaboration Networks'. This research observes a virtual organization as a form of collaborative networks, and measures the degree of virtualization of Korean collaborative organizations.

• Journal of Ubiquitous Convergence Technology
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• v.1 no.1
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• pp.3-8
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• 2007

This paper presents a set of techniques used in a real-time visual surveillance system. The system is implemented on a low-cost embedded DSP platform that is designed to work with stationary video sources. It consists of detection, a tracking and a classification module. The detector uses a statistical method to establish the background model and extract the foreground pixels. These pixels are grouped into blobs which are classified into single person, people in a group and other objects by the dynamic periodicity analysis. The tracking module uses mean shift algorithm to locate the target position. The system aims to control the human density in the surveilled scene and detect what happens abnormally. The major advantage of this system is the real-time capability and it only requires a video stream without other additional sensors. We evaluate the system in the real application, for example monitoring the subway entrance and the building hall, and the results prove the system's superior performance.