• 대한토목학회논문집
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• 제33권5호
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• pp.2107-2124
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• 2013

현재 국내의 교량 구조물에 대한 점검은 관리대장에 기록하여 컴퓨터로 전산화시키는 과정으로 이루어져 있다. 이는 수동-아날로그 형태로 자료의 신뢰성 저하, 비효율적 관리자료, 주관적인 평가로 인하여 교량 구조물에 대한 잠재적인 문제점이 발생하였다. 본 논문은 이러한 문제점을 해결하기 위하여 효율화, 관리화, 편리화를 목표로 점검자가 현장에서 교량 구조물의 정확한 유지관리를 통해 사회기반시설로서의 주목적인 안정성을 달성하도록 첨단 IT 기술인 RFID를 적용한 지능형 교량 유지관리 시스템을 제안하였다. 이 시스템은 현장에서 점검시간의 단축으로 효율적인 점검과 전산화된 DB를 이용하여 신뢰성 높은 자료의 관리 및 활용이 용이하고, 평가의 객관화로 교량 구조물의 정확한 판단이 가능하다. 또한 장소에 상관없이 효과적인 유지관리를 통한 업무수행을 확인하였다.

• 에너지공학
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• 제15권3호
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• pp.181-187
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• 2006

본 논문에서는 소방 비상용으로 이용되는 태양전지 발전시스템을 제안하고, 발전시스템의 효율을 증대시키기 위한 새로운 고효율의 전력변환장치(승압용 초퍼와 인버터)가 설계된다. 직류-직류(DC-DC) 승압용 초퍼와 직류-교류(DC-AC) 인버터는 사용된 제어스위치들의 스위칭 손실을 최소화하기 위해 공진회로를 이용한 새로운 소프트 스위칭 기법이 적용되고 시스템의 효율을 증대시킨다. 또한 본 논문에서는 태양전지(solar cell)의 최대전력 전송에 의한 태양전지의 효율적인 사용을 위한 태양전지 발전전력의 최대점 $P_{max}$을 손쉽게 추종하고 검출하는 새로운 제어기법과 제어회로에 대해 상세히 해석된다. 고효율의 전력변환 장치와 태양전지 최대전력 전송회로는 컴퓨터 시뮬레이션과 실험을 통하여 그 타당성이 입증된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권2호
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• pp.974-987
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• 2018

This paper presents a novel and efficient data transmission scheme based on mobile edge computing for the massive IoT environments which should support various type of services and devices. Based on an accurate and precise synchronization process, it maximizes data transmission throughput, and consistently maintains a flow's latency. To this end, the proposed efficient software defined data transmission scheme (ESD-DTS) configures and utilizes synchronization zones in accordance with the 4 usage cases, which are end node-to-end node (EN-EN), end node-to-cloud network (EN-CN), end node-to-Internet node (EN-IN), and edge node-to-core node (EdN-CN); and it transmit the data by the required service attributes, which are divided into 3 groups (low-end group, medium-end group, and high-end group). In addition, the ESD-DTS provides a specific data transmission method, which is operated by a buffer threshold value, for the low-end group, and it effectively accommodates massive IT devices. By doing this, the proposed scheme not only supports a high, medium, and low quality of service, but also is complied with various 5G usage scenarios. The essential difference between the previous and the proposed scheme is that the existing schemes are used to handle each packet only to provide high quality and bandwidth, whereas the proposed scheme introduces synchronization zones for various type of services to manage the efficiency of each service flow. Performance evaluations show that the proposed scheme outperforms the previous schemes in terms of throughput, control message overhead, and latency. Therefore, the proposed ESD-DTS is very suitable for upcoming 5G networks in a variety of massive IoT environments with supporting mobile edge computing (MEC).

• 패션비즈니스
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• 제20권3호
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• pp.17-29
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• 2016

To develop baseball catcher leg guards, 3-dimensional (3D) methodologies, which are 3D human body data, reverse engineering, modeling, and printing, optimized guard design for representative positions. Optimization was based on analysis of 3D body surface data and subjective evaluation using 3D printing products. Reverse engineering was used for analysis and modeling based on data in three postures: standing, $90^{\circ}$ knee flexion, and $120^{\circ}$ knee flexion. During knee flexion, vertical skin length increased, with the thigh and knee larger in anterior area compared to the horizontal dimension. Moreover, $120^{\circ}$ knee flexion posture had a high radius of curvature in knee movement. Therefore, guard designs were based on increasing rates of skin deformation and numerical values of radius of curvature. Guards were designed with 3-part zoning at the thigh, knee, and shin. Guards 1 and 2 had thigh and knee boundaries allowing vertical skin length deformation because the shape of thigh and knee significantly affects to its performance. Guard 2 was designed with a narrower thigh and wider knee area than guard 1. The guards were manufactured as full-scale products on a 3D printer. Both guards fit better in sitting than standing position, and guard 2 received better evaluations than guard 1. Additional modifications were made and an optimized version (guard 3) was tested. Guard 3 showed the best fit. A design approach based on 3D data effectively determines best fitting leg guards, and 3D printing technology can customize guard design through immediate feedback from a customer.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.13-16
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• 2008

Solid oxide fuel cell(SOFC) is an electrochemical energy conversion system with high efficiency and low-emission of pollution. In order to reduce the operating temperature of SOFC system under $800^{\circ}C$, the thickness reduction of YSZ electrolyte to be as thin as possible, e.g., less than 10 ${\mu}m$ are considered with the microstructure control and optimum design of unit cell. Methods for reducing the thickness of YSZ electrolyte have been investigated in coin cell. Moreover, a large unit cell($8cm{\times}8cm$) for SOFC was fabricated using an anode-supported electrolyte assembly with a thinner electrolyte layer, which was prepared by a tape casting method with a co-sintering technique. we studied the design factors such as active layer, electrolyte thickness, cathode composition, etc,. by the coin type of unit cell ahead of the fabrication process of a large unit cell and also reviewed about the evaluation technique of a large size unit cell such as interconnect design, sealing materials and current collector and so forth. Electrochemical evaluations of the unit cells, including measurements such as power density and impedance, were performed and analyzed. Maximum power density and polarization impedance of coin cell were 0.34W/$cm^2$ and $0.45{\Omega}cm^2$ at $800^{\circ}C$, respectively. However, Maxium power density of a large unit cell($5cm{\times}5cm$) decreased to 0.21W/$cm^2$ at $800^{\circ}C$ due to the increase of ohmic resistance. However, It was found that the potential value of a large unit cell loaded by 0.22A/$cm^2$ showed 0.76V at 100hrs without the degradation of unit cell.

• 비파괴검사학회지
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• 제35권1호
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• pp.52-60
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• 2015

원자력발전소에는 탄소강과 스테인리스강 용접을 위해 alloy600 용접재를 적용한 이종금속용접부가 다수 존재하며, 전 세계적으로 이종금속용접부에서 결함 발생 보고가 지속되고 있다. 주기적인 건전성 평가를 위해 이종금속용접부 초음파검사 일반절차서 (KPD-UT-10)를 적용하여 검사를 수행하고 있으며, 검사절차서에서는 탐촉자와 검사체 표면 사이의 간격을 최대 1/32"(0.8mm) 이내로 제한하고 있다. 국내의 일부 이종금속용접부는 테이퍼진 형상과 불규칙한 표면 형상을 가지고 있어, 가변형 위상배열초음파기술을 적용하여 검사 신뢰성을 높이고자 본 연구를 수행하였다. 연구 결과, 검사체 표면이 불규칙한 시편 내부의 인공결함에 대한 검출이 양호하였고, 이를 통해, 가변형 위상배열초음파기술의 현장 적용 가능성을 확인하였다.

• 한국식품영양과학회지
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• 제14권3호
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• pp.249-252
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• 1985

건시(乾枾)의 품질(品質)에 관한 연구(硏究)로서 국내(國內)의 4품종(品種)과 외국(外國)의 한품종(品種)을 선정(選定)하여 실험실적(實驗室的)으로 건시(乾枾)를 제조(製造)하여 이들의 당조성(糖組成)과 물성(物性)을 측정(測定)하였고 관능검사(官能檢査)를 실시한 結果(結果)를 요약하면 다음과 같다. 1. 건시(乾枾)의 구성당(構成糖)은 glucose, fructose, sucrose 였으며 건시과육(乾枾果肉)의 당조성(糖組成)은 품종(品種)에 따라 약간씩 다르나 glucose와 fructose가 비슷한 함량(含量)을 나타내고 있었으며 sucrose는 극미량에 불과했다. 2. 건시(乾枾)의 물성중(物性中) fracturability, hardness는 남양 수시가 가장 높았으며 대개의 parameter가 남양수시와 고종시에서 비교적(比較的) 높게 나타났고 평핵무(平核無)와 상주둥시는 거의 모든 parameter에서 비교적(比較的) 낮게 나타났다. 3. 물물성측정(物物性測定)의 결과(結果)로부터 건조 남양수시와 고종시는 딱딱하고 질긴 조직(組織)을 나타냈으며 평핵무(平核無)와 상주둥시는 비교적(比較的) 건시(乾枾)로서 양호한 조직(組織)을 가짐을 알 수 있었다. 4. 관능검사(官能檢査)에 의한 품질비교(品質比較)에 있어서는 거의 모든 항목에서 평핵무(平核無), 상주둥시, 청도반시, 남양수시의 순(順)이었다.

• 한국정보처리학회논문지
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• 제7권12호
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• pp.3794-3803
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• 2000

주문형 비디오 서버(Video-on-Demand server)에서 멀티미디어 데이터를 효과적으로 서비스 하기 위해 사용되는 승인제어는 시스템의 정확한 여유 자원 상태의 파악을 통해서 이루어져야 한다. 여러 자원 중에서도 디스크 자원은 요구에 대한 응답 시간이 디스크 외적인 요소에 의해 불규칙적이며 요구량 또한 편차카 크므로 적응성 있는 승인 제어가 필요하다. 기존의 승인 제어 기법에서는 이론적인 수치를 통해 승인 여부를 판단하였고, 실측에 기반할 지라도 서비스 상황에 따른 대처가 미흡했다. 본 논문에서 제안하는 실측 기반 적응형 확률 승인 제어 기법은 실제 서비스 환경에서 오프라인(Off-line) 처리 과정과 온라인(On-line) 처리 과정의 두 단계를 실시한다. 이를 통해 시스템의 자원 상황을 정확히 파악할 수 있고 상황에 따라 적응성 있게 승인 여부를 결정할 수 있다. 따라서 최대한의 자원 활용과 QoS(Quality of Service)를 동시에 보장할 수 있다. 모의 실험에서는 실측을 통해 얻어진 성능의 정확성과 요구 대역폭에 따른 적응성 있는 제어를 보임으로써 비디오 서버가 QoS를 보장하면서 최대한의 자원 활용이 가능함을 보였다.

• Journal of Korean Neurosurgical Society
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• 제48권2호
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• pp.139-144
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• 2010

Objective : We report our surgical experience in the treatment of 16 consecutive patients with benign craniovertebral junction (CVJ) tumor, observed from 2003 to 2008 at our department. Methods : We had treated 6 foramen magnum meningiomas, 6 cervicomedullary hemangioblastomas, 1 accessory nerve schwannoma, 1 hypoglossal nerve schwannoma, 1 C2 root schwannoma, and 1 cavernous hemangioma. Clinical results were evaluated by Karnofsky Performance Scale (KPS) and all patients underwent preoperative neuroradiological evaluation with computed tomography (CT) and magnetic resonance image (MRI). Angiography was performed in 15 patients and preoperative embolization was done in 2 patients. Results : Five far-lateral, 1 supracondylar and 10 midline suboccipital approaches were performed. Gross total removal was achieved in 15 cases (94%) and subtotal removal in 1 patient (6%). None of the patients required occipitocervical fusion. Radiological follow-up showed no recurrence in cases totally removed. Postoperative decrease of KPS scores was recorded in only 1 patient. The treatment of cervicomedullary solid hemangioblastoma presented particular issues : by preoperative embolization, we removed tumor totally without an excessive bleeding or brainstem injury. In one of foramen magnum meningioma, we carried out subtotal removal due to hard tumor consistency and encasement of neurovascular structures. Conclusion : The choice of surgical approaches and the extent of bone resection should be defined according to the location and size of individual tumors. Moreover, we emphasize that preoperative neuroradiological evaluations on presumptive tumor type could be helpful to the surgeon in tailoring the technique and providing the required exposure for different lesions, without unnecessary surgical steps.

• Nuclear Engineering and Technology
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• 제37권5호
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• pp.479-490
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• 2005

The thermalhydraulic performance of a CANDU-6 reactor loaded with various CANFLEX fuel bundles is evaluated by the NUCIRC code, which is incorporated with recent models of pressure drop and critical heat flux (CHF) predictions based on high-pressure steam-water tests for the CANFLEX bundle as well as a 37-element bundle. The distributions of channel flow rate, channel exit quality, critical channel power (CCP), and critical power ratio (CPR) for the CANFLEX bundles (with natural or recycled uranium fuel) in the CANDU-6 reactor fuel channel are calculated by the code. The effects of axial and radial heat flux on CCP are evaluated by assuming that the recycled uranium fuel (CANFLEX-RU) has the same geometric data as the natural uranium fuel bundle (CANFLEX-NU), but a different power distribution due to different fuel composition and refueling scheme. In addition, the effects of pressure tube creep and bearing-pad height are examined by comparing various results of uncrept, and $3.3\%\;and\;5.1\%$ crept channels loaded with CANFLEX bundles with 1.4 mm or 1.7 mm high bearing-pads with those of the 37-element bundle. The distributions of the channel flow rate and CCP for the CANFLEX-NU or -RU bundle show a typical trend for a CANDU-6 reactor channel, and the CPRs are maintained above at least 1.444 (NU) or 1.455 (RU) in the uncrept channel. The enhanced CHF of the CANFLEX bundle (particularly with 1.7mm height bearing-pads) produces a higher thermal margin and considerably less sensitivity to CCP reduction due to the pressure tube creep than the 37-element bundle. The CCP enhancement due to the raised bearing-pads is estimated to be about $3\%\~5\%$ for the CANFLEX-NU and $2\%\~6\%$ for the CANFLEX-RU bundle, respectively.