• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.834-840
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• 2001

Gear is general mechanical elements that used for power transmission between two shafts that interval is comparatively short. and it delivers big power as accurate ratio of speed. The profile of Spur gear which is the most basic factor is divided into Trochoidal fillet curve and Involute curve. Involute curve is used a lot of a shaped curve of machine parts such as a gear, a scroll compressor and a collar of centrifugal pump. However, It is poor to study the modeling of Trochoidal fillet curve and the three dimensions model shaped mathematical curve. This paper describes a mathematical model of profile shifted involute gear. and this model is based on Camus's theory. We draw three dimensions gear have accurate mathematical function using ADS, VisualLISP. and To check accuracy and perfection, we make a program of checking Interference. and use for this study.

• Journal of Communications and Networks
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• 제5권3호
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• pp.187-196
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• 2003

We consider the use of error control coding in direct sequence-code-division multiple access (OS-COMA) systems that employ multiuser detection (MUO) and space diversity. The relative performance gain between Reed-Solomon (RS) code and convolutional code (CC) is well known in [1] for the single user, additive white Gaussian noise (AWGN) channel. In this case, RS codes outperform CC's at high signal-to-noise ratios. We find that this is not the case for the multiuser interference channel mentioned above. For useful error rates, we find that soft-decision CC's to be uniformly better than RS codes when used with DS-COMA modulation in multiuser space-time channels. In our development, we use the Gaussian approximation on the interference to determine performance error bounds for systems with low number of users. Then, we check their accuracy in error rate estimation via system's simulation. These performance bounds will in turn allow us to consider a large number of users where we can estimate the gain in user-capacity due to channel coding. Lastly, the use of turbo codes is considered where it is shown that they offer a coding gain of 2.5 dB relative to soft-decision CC.

• 전자공학회논문지
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• 제54권6호
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• pp.17-21
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• 2017

홀로그래픽 데이터 저장장치는 높은 데이터 전송률과 저장용량이 매우 크기 때문에 차세대 저장장치 후보 중 하나이다. 하지만 홀로그래픽 데이터 저장장치의 오류요인으로는 인접 페이지간 간섭 및 2차원 인접 심볼간 간섭이 있다. 또한 물리적 영향에 의해 발생되는 연집오류가 있다. 본 논문에서는 이러한 연집오류를 정정하고 성능을 향상시키기 위해 수정된 로그-우도비값과 부가적 정보를 반복적으로 사용하는 방식을 제안한다. 제안하는 LDPC 곱부호는 일반적인 LDPC 부호와 비교하여 BER이 $10^{-5}$일 때, 약 0.5dB 성능 향상을 보였다.

• 한국소음진동공학회논문집
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• 제18권1호
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• pp.94-100
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• 2008

Noise barriers are being used more often to solve problems of noise pollution from traffic noise. Several types of noise barriers are being installed to increase the cost-effectiveness of noise barrier installation. In this study, the insertion loss is analyzed to evaluate the effectiveness of the noise barrier by using the BEM. In order to check the validity of the BEM, the BEM and Lam's theoretical analysis are compared with measurement, which is performed in the anechoic chamber for the 1/10 scale-down model, and good agreements are obtained. By using the two dimensional boundary element method, the insertion loss is calculated and analyzed for several typical noise barriers such as the vertical barrier, the barrier with an oblique edge on top, the T-shaped barrier and the barrier with interference device on top. With these analyses, it is possible to design more cost-effective noise barriers appropriate for a particular area.

• 한국기계가공학회지
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• 제18권11호
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• pp.24-34
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• 2019

An automotive automatic transmission is a popular power-transmitting device in passenger vehicles, as it provides various speed ratios for diverse driving conditions with easy manipulation and smooth gear shifting. The transmission is mainly composed of input and output shafts, planetary gear sets, brakes/clutches, and housing, and it yields multiple forward gears and one reverse gear by actuating the shifting devices of the brakes and clutches. In developing a new transmission, kinematic configurations of a transmission, which presents a brief structure and actuation schemes for speed ratios, need to be checked to determine if the structure can be assembled in a layout. It is impossible for a transmission concept having any interference in connecting main components to be developed further in the design process, since connection interference leads to failure of a layout design in the 2-D plane. In this research, an analysis of the assemblability of a front-wheel drive automatic transmission is carried out on an example concept design by applying the vertex addition algorithm based on graph theory.

• 대한조선학회논문집
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• 제46권5호
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• pp.545-551
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• 2009

In naval architecture and offshore engineering, the development and a broad use has been achieved in the field of flow control valves for pipe system. Butterfly valves are also widely used for flow control, but there are not many studies for triple-eccentric butterfly valves. Moreover, if the fluid of pipeline flows in the bi-direction then it makes more complicate to adapt triple-eccentric butterfly valves to flow control. In this study, we are trying to develop a bi-directional triple-eccentric butterfly valve through sealing mechanism and stem design study. Digital mockup using 3D CAD was constructed for shape interference check and structural analysis was conducted for structural safety. Also we performed leakage test to check out the durability of the bi-directional pressure for the developed valve.

• Ocean and Polar Research
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• 제42권3호
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• pp.195-210
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• 2020

The observed time series from the Korea Ocean Research Stations (KORS) in the Yellow and East China Seas (YECS) have various sources of noise, including bio-fouling on the underwater sensors, intermittent depletion of power, cable leakage, and interference between the sensors' signals. Besides these technical issues, intricate waves associated with background tidal currents tend to result in substantial oscillations in oceanic time series. Such technical and environmental issues require a regionally optimized automatic quality control (QC) procedure. Before the achievement of this ultimate goal, we examined the approach of the Ocean Observatories Initiative (OOI)'s standard QC to investigate whether this procedure is pertinent to the KORS. The OOI QC consists of three categorized tests of global/local range of data, temporal variation including spike and gradient, and sensor-related issues associated with its stuck and drift. These OOI QC algorithms have been applied to the water temperature time series from the Ieodo station, one of the KORS. Obvious outliers are flagged successfully by the global/local range checks and the spike check. Both stuck and drift checks barely detected sensor-related errors, owing to frequent sensor cleaning and maintenance. The gradient check, however, fails to flag the remained outliers that tend to stick together closely, as well as often tend to mark probably good data as wrong data, especially data characterized by considerable fluctuations near the thermocline. These results suggest that the gradient check might not be relevant to observations involving considerable natural fluctuations as well as technical issues. Our study highlights the necessity of a new algorithm such as a standard deviation-based outlier check using multiple moving windows to replace the gradient check and an additional algorithm of an inter-consistency check with a related variable to build a standard QC procedure for the KORS.

• Journal of Oral Medicine and Pain
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• 제44권3호
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• pp.92-102
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• 2019

Purpose: To investigate the masticatory function of patients with different temporomandibular disorders (TMD) phenotypes, and to explore the risk factors for the masticatory function of TMD patients among multiple biopsychosocial variables using patient-reported outcomes (PROs). Methods: Clinical features and TMD diagnoses of 250 cases were investigated by reviewing medical records. Psychosocial factors were evaluated using four questionnaires representing pain severity and pain interference (Brief Pain Inventory), pain catastrophizing (Pain Catastrophizing Scale, PCS), psychological distress (Symptom Check List-90-Revised, SCL-90R) and kinesiophobia (Tampa Scale for Kinesiophobia for Temporomandibular Disorders, TSK-TMD). Masticatory function, as a dependent variable, was determined using the Jaw Functional Limitation Scale (JFLS). Kruskal-Wallis test and Spearman's rank correlation were used for analyses. Results: A total of 145 cases were included and classified into four subgroups including group 1: TMD with internal derangement without pain (n=14), group 2: TMD with muscle pain (n=32), group 3: TMD with joint pain (n=60) and group 4: TMD with muscle-joint combined pain (n=39). Pain severity (p=0.001) and interference (p=0.022) were the highest in group 2, but the mean global score of JFLS was the highest in group 3, followed by group 4, group 2, and group 1 (p=0.013). Pain severity, pain interference, the mean global score of PCS and the mean global score of TSK-TMD showed significant and moderate correlation with the mean global score of JFLS. All subdimensions and the global severity index of SCL-90R had significant, but weak correlations with all scores of JFLS. Conclusions: The results suggest that masticatory functional limitation depends on the TMD phenotypes. Among the various PROs, pain perception, pain catastrophizing and kinesiophobia seem to be more influential risk factors on jaw function than psychological distress, such as depression and anxiety.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.666-669
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• 2002

In this Research, we would like to perform optimal design by using theoretical equation and experimental equation for development of transmission and P.T.O on work vehicle with multi-function that is suited fruit cultures in my country. For the purpose of reducing development period about product and minimizing risk about design error, detail design and interference check are accomplished by FEM analysis and CAD software.

• 한국생산제조학회지
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• 제6권4호
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• pp.19-26
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• 1997

The manufacture of an impeller typically requires the 5-axis CNC machining, since the impeller is usually under working conditions such as high speed, high temperature, and high pressure. Thus, this study contributes to development of an exclusive CAM system for effective 5-axis CNC machining of a ruled surface type impeller. In this study, the sampled impeller is made of blades and a body and the blade consists of ruled surfaces between hub curve and shroud curve. In the post processing for 5-axis NC part program, the cutter axis direction vector is the straighten vector on ruled surface. The position of ball center in ball end mill cutter is decided on the interference check between the cutter and body surface of impeller using with the modified z-map method that z-axis is the same of cutter axis direction vector. The exclusive CAM system for an impeller developed in this study was very effective for designs and 50-axis machining of a ruled surface type impeller.