• 대한토목학회논문집
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• 제26권2B호
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• pp.187-195
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• 2006

본 연구에서는 세굴에 의한 교량기초의 위험도를 평가하고 효율적인 방재 대책수립을 위해 국내 세굴 특성을 고려한 교량 세굴 유지관리 시스템을 개발하였다. 본 시스템은 GIS 기반 프로그램으로서 교량세굴 자료의 저장, 검색 및 출력이 가능하며, 크게 교량세굴 위험도에 따른 우선순위의 결정 및 유지관리 시스템의 두 부분으로 나뉜다. 교량에 대한 기존의 간단한 자료를 이용하여 초기 분류과정을 거쳐 현장 상세조사 우선순위가 결정되며, 이에 따라 현장 상세조사와 세굴 해석을 실시하여 교량세굴 위험도 등급을 결정한다. 위험도 등급은 예상 세굴심과 그에 따른 기초의 지지력 변화, 기초의 종류 및 근입깊이, 현재의 세굴 진행상태 등을 고려하여 모두 6등급으로 나뉘며 그 결과는 화면상에 표시되고 모든 자료는 데이터베이스 시스템에 저장되어 관리된다.

• Journal of Information Display
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• 제9권3호
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• pp.16-22
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• 2008

A novel class of conjugated dendritic molecules bearing N-hexyl-substituted carbazoles as peripheral groups and various conjugative aromatic cores was synthesized through Heck coupling and the Horner-Emmons reaction. A multilayered structure of ITO/PEDOT:PSS (30 nm)/emitting material (50 nm)/BCP (10 nm)/$Alq_3$ (10 nm)/LiF (1 nm)/Al (100 nm) was employed to evaluate the synthesized dendritic materials. The electroluminescence spectrum of the multilayered device made of 3Cz predominantly exhibited blue emissions. Similar emissions were observed in the PL spectra of it's the device's thin film. The multilayered devices made of 3Cz, 3BCz, and 4BCz showed luminance values of 6,250 cd $m^{-2}$ at 24 V, 3,000 cd $m^{-2}$ at 25 V, and 1,970 cd $m^{-2}$ at 36 V, respectively. The smallest molecule, 3Cz, which bore three carbazole peripheral groups, exhibited a blue-like emission with CIE 1931 chromaticity coordinates of x = 0.17 and y = 0.21.

• 무역상무연구
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• 제52권
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• pp.25-44
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• 2011

Possibility of credit risk, foreign exchange risk and interest rate risk of exporter increases in the recent international Commercial transactions, due to financial crisis of Europe and liberalization of Middle East. Under this circumstance, Forfaiting is trade finance that forfaiter purchase negotiable debt instrument without recourse from exporter, which occurred related with international commercial transactions, and credit risk, contingency risk, foreign exchange risk and interest rate risk of exporter can be transferred to forfaiter. Forfaiting is typically medium-term finance(three to five years) concluded at fixed interest rate, although it can also arranged on a floating interest-bearing basis for periods from six months to ten years or more. But Forfaiting service of Korea has limitation as follows. First, forfaiting in Korea deals with unrestricted irrevocable documentary credit as debt instruments. Period that forfaiting is provided is short and amount of money is limited, compared with advanced forfaiting. But forfaiting provided in advanced countries deals with various methods such as guarantee for bill, payment guarantee, and can be resold in financial market. Recently importance of forfaiting is increasing in international commercial transactions. Therefore profound study on forfaiting is required. The study will examine the risk that happens to the concerned parties in forfaiting, and its management measures. The study adopted literature review method such as local and foreign books and papers about trade finance, internet information about forfaiting, and professional journal related with international finance.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.435-442
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• 2002

본 연구에서는 사장교의 제어기법 개발을 위한 구조물로 제공되는 벤치마크(benchmark) 사장교에 대해 복합제어 기법을 적용하였다. 이 벤치마크 문제에서는 2003년 완공 예정으로 미국 Missouri 주에 건설 중인 Cape Girardeau 교를 대상 구조물로 고려하였다. Cape Girardeau 교는 New Madrid 지진구역에 위치하고, Mississippi 강을 횡단하는 주요 교량이라는 점 때문에 설계단계에서부터 내진 문제에 대하여 자세하게 고려되었다. 상세 설계도면을 기반으로 하여 교량의 전체적인 거동 특성을 정확하게 나타낼 수 있는 3차원 모델이 만들어졌고, 사장교의 제어 성능에 관련된 평가 기준이 수립되었다. 본 연구에서 사용한 복합제어 기법이란 지진하중으로 인해 구조물에 발생되는 하중을 줄이기 위한 수동제어 기법과 상판변위와 같은 구조물의 응답을 추가적으로 제어하기 위한 능동제어 기법이 결합된 제어방법이다. 수동제어 장치로는 현재 일반적으로 많이 사용되고 있는 납고무받침(lead rubber bearing)을 사용하였다. 능동제어 방법에는 $H_2$/LQG 제어 알고리듬(algorithm)을 사용하였다. 수치해석 결과 제안방법의 성능은 수동제어 방법에 비해 매우 효과적이며, 능동제어 방법에 비해서는 좀더 좋은 제어성능을 나타내었다. 또한, 복합제어 방법은 수동제어 부분 때문에 능동제어 방법에 비해 좀더 신뢰할 수 있는 제어 방법이다. 따라서 제안된 제어방법은 지진하중을 받는 사장교의 제어를 위해 효과적으로 사용될 수 있다.

• 대한족부족관절학회지
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• 제18권2호
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• pp.43-47
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• 2014

Hallux valgus is a lateral deviation of the first phalanx and medial deviation of the first metatarsal at the first metatarsophalangeal (MP) joint. Its incidence has increased due to developing footwear. The etiologies include fashion footwear, genetic causes, anatomical abnormality around the foot, rheumatoid arthritis, and neuromuscular disorders. Physiologic alignment of the first MP joint is maintained by congruent and symmetric alignment of the articular surface of the first proximal phalanx and first metatarsal head, physiologic relationship of the distal first metatarsal articular surface and the first metatarsal shaft axis, and stable balance of soft tissue around the first MP joint and stable tarsometatarsal joint. Several factors have been associated with hallux valgus, including pes planus, hypermobility of the first tarsometatarsal joint, flattened shape of the first metatarsal head, increased distal metatarsal articular angle, and deformation of the medial capsular integrity. History and physical examination are very important to diagnosis of hallux valgus. Simple radiography provides information on deformity, particularly in weight-bearing anteroposterior and lateral radiographs. Understanding the etiologies and pathophysiology is very important for success in treatment of patients with hallux valgus.

• 말소리와 음성과학
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• 제2권3호
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• pp.171-178
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• 2010

This study examined the relationship between speech intelligibility and comprehensibility for hearing impaired children with cochlear implants. Speech intelligibility was measured by orthographic transcription method for acoustic signal at the level of words and sentences. Comprehensibility was evaluated by examining listener's ability to answer questions about the contents of a narrative. Speech samples were collected from 12 speakers(age of 6~15 years) with cochlear implants. For each speaker, 4 different listeners(total of 48 listeners) completed 2 tasks: One task involved making orthographic transcriptions and the other task involved answering comprehension questions. The results of the study were as follows: (1) Speech intelligibility and comprehensibility scores tended to be increased by decreasing of severity. (2) Across all speakers, the relationship was significant between speech intelligibility and comprehensibility scores without considering severity. However, within severity groups, there was the significant relationship between comprehensibility and speech intelligibility only for moderate-severe group. These results suggest that speech intelligibility scores measured by orthographic transcription may not accurately reflect how well listener comprehend speech of children with cochlear implants and therefore, measures of both speech intelligibility and listener comprehension should be considered in evaluating speech ability and information-bearing capability in speakers with cochlear implants.

• Journal of Mechanical Science and Technology
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• 제18권9호
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• pp.1668-1679
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• 2004

The design of an axial piston pump for electro-hydrostatic transmission systems requires accurate information where and how much the internal friction and flow losses are produced. This study is particularly focused on the friction losses of a bent-axis type hydraulic piston pump, aiming at finding out which design factors influence its torque efficiency most significantly. To this end, the friction coefficients of the pump parts such as piston heads, spherical joints, shaft bearings, and valve plate were experimentally identified by a specially constructed tribometer. Applying the experimental data to the equations of motion for pistons as well as to the theoretical friction models for the pump parts, the friction torques produced by them were computed. The accuracy of the computed results was confirmed by the comparison with the practical input torque of the pump. In this paper, it is shown that the viscous friction forces on the valve plate and input shaft bearing are the primary source of the friction losses of the bent-axis type pump, while the friction forces and moments on the piston are of little significance.

• 한국경영과학회지
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• 제24권4호
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• pp.157-170
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• 1999

The web-based groupware systems hold many possibilities for system developers and users. Especially, web-based group collaborative systems are emerging as enterprise-wide information systems. Since data in group collaborative systems are apt to be shared among multiple concurrent users and modified simutaneously by them, the web-based group collaborative systems must support synchronous collaboration in order to provide users with synchronized and consistent views of shared data. However, current web technologies have limitations in supporting this, largely because the existing Hypertext Transfer Protocol(HTTP) is unidirectional and does not allow web servers to send messages to their web browsers without first receiving requests from them. This paper proposes an active web server that can overcome such limitations and facilitate synchronous collaboration in web-based group collaborative systems. To accomplish such goals, the active web server manages dependency relationships beween shared data and web browsers referencing them and actively propagates changing details of the shared data to all web browsers referencing them. And, this paper examines usefulness and effectiveness of the active web server to apply it to the ball-bearing design example of concurrent engineering design systems. The prototype system of the active web server is developed on a commercial Object-oriented Database Management System(0DBMS) called OBJECTSTERE using the C++ programming language.

• 한국소음진동공학회논문집
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• 제12권10호
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• pp.799-807
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• 2002

The vibration signal can give an indication of the condition of rotating machinery, highlighting potential faults such as unbalance, misalignment and bearing defects. The features in the vibration signal provide an important source of information for the faults diagnosis of rotating machinery. When additional training data become available after the initial training is completed, the conventional neural networks (NNs) must be retrained by applying total data including additional training data. This paper proposes the fault diagnostics algorithm using the ART-Kohonen network which does not destroy the initial training and can adapt additional training data that is suitable for the classification of machine condition. The results of the experiments confirm that the proposed algorithm performs better than other NNs as the self-organizing feature maps (SOFM) , learning vector quantization (LYQ) and radial basis function (RBF) NNs with respect to classification quality. The classification success rate for the ART-Kohonen network was 94 o/o and for the SOFM, LYQ and RBF network were 93 %, 93 % and 89 % respectively.

• 한국소음진동공학회논문집
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• 제27권2호
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• pp.204-212
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• 2017

The rotor dynamics and balancing technic for rotating equipment during engineering and manufacture stage are to be carefully considered in order to minimize the operation troubles regarding vibration during commissioning stage. In this paper, the test rig, which includes the disks as balancing plane, is designed and manufactured, so that the characteristic of rotor dynamics can be analyzed such as critical speed and mode shape. The critical speed predicted through natural frequency analysis is verified by the actual measurement on bearing housing vibration during start-up condition of test rig. The low speed balancing and the operating speed balancing test are performed respectively with consideration of first critical speed, and the residual unbalance amounts are estimated in accordance with the relevant method described in API standard. In addition, the single and dual plane balancing are carried out on main disk and trim disk depended on phase information at each balancing step.