• Journal of Chest Surgery
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• v.41 no.2
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• pp.216-222
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• 2008

Background: Prosthetic annuloplasty rings are used for the reconstruction of the mitral valve annulus. However, there is controversy over the best ring to use for reconstruction. In this study, we evaluated the long term result of using a Teflon felt strip as an alternative to commercial rings. Material and Method: From 1996 to 2007, we enrolled 47 patients with pure mitral regurgitation greater than grade III. All patients had an ejection fraction of 40% or more. Patients with congenital heart disease or other valvular heart disease were excluded from this study. They were divided into two groups; the commercial ring group (Group CR) and the Teflon felt ring group (Group TF). Result: There was no mortality. The postoperative echocardiography showed no significant change in the overall ejection fraction (from $58.0{\pm}11.2%\;to\;42.8{\pm}8.4%$). There were no significant differences between the two groups with regard to morbidity, the reoperation rate and recurrence of mitral regurgitation greater than grade II. Conclusion: The long term results from this study showed that posterior mitral annuloplasty using Teflon felt had similar results compared to annuloplasty using commercial rings.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.771-777
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• 2008

In this paper, a frequency doubler using modified time-delay technique is proposed. A voltage controlled delay line (VCDL) in the proposed frequency doubler compensates the group delay time mismatching between input and delayed signal. With the group delay time matching and waveform shaping using the adjustable Schmitt triggers, the unwanted fundamental component($f_0$) and the higher order harmonics such as third and fourth are diminished excellently. In result, only the doubled frequency component($2f_0$) appears dominantly at the output port. The frequency doubler is designed at 1.15 GHz of $f_0$ and fabricated with TSMC $0.18\;{\mu}m$ CMOS process. The measured output power at $2f_0$ is 2.67 dBm when the input power is 0 dBm. The obtained suppression ratio of $f_0,\;3f_0$, and $4f_0$ to $2f_0$ are 43.65, 38.65 and 35.59 dB, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.25-33
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• 2017

This paper reports the optical design of the MR-16 lamp series with a LED second lens and an aspherical plano-convex lens suitable for a simple and rapid injection molding fabrication method. The fabrication and performance evaluation of the MR-16 lamp series, which was designed with a narrow angular distribution of luminous intensity, were conducted to replace halogen lamps with LED lamps. Four types of LED lamps were fabricated, which have angular distributions of luminous intensity of $22.4^{\circ}$, $31.1^{\circ}$, $37.3^{\circ}$, and $59.9^{\circ}$ and luminous efficiencies of 76.5 lm/W, 75.2 lm/W, 72.0 lm/W, and 77.8 lm/W, respectively, while their spreading angles with an illuminance uniformity of 81% were $3^{\circ}$, $15^{\circ}$, $22^{\circ}$, and $49^{\circ}$, respectively. After eliminating a yellow tail of the LED lamps using a diffusion sheet, the angular distributions of the luminous intensity were measured to be $20.8^{\circ}$, $31.5^{\circ}$, $37.8^{\circ}$, and $68.7^{\circ}$.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.6
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• pp.1-8
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• 1992

본 고에서는 균질화법의 정식화를 이용하여 복합재료의 거시적 균질화된 재료상수를 구하고, 이 재료상수를 이용하여 거시구조물의 변형과 응력을 구하고, 이로부터 다시 미시구조의 응력분포와 변형도를 구하는 방법을 기술하였다. 주기성을 가정한 균질화법은 복합재료 구조물의 물성평가와 거동예측에 대한 매우 적절한 수치해석 방법이다. 균질화법은 이러한 선형변형의 문제뿐만 아니라, 내압을 존재하는 빈공간 소재의 물성, 기지재료와 강화재료 계면의 미끄러짐 등으로 인한 미세 파손현상 등의 예측이 가능하다. 그외에도 탄소성 대변형 거동 이론과 균질화법을 함께 적용하여, squeeze casting에서 발생하기 쉬운 계면분리나 파단 등의 미소결함과 같은 2차 성형성의 예측도 가능하다.

• 한국전산유체공학회:학술대회논문집
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• 2000.10a
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• pp.129-134
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• 2000

An efficient numerical method to solve the unsteady incompressible Navier-Stokes equations is developed. A fully implicit time advancement is employed to avoid the CFL(Courant-Friedrichs-Lewy) restriction, where the Crank-Nicholson discretization is used for both the diffusion and convection terms. Based on a block LU decomposition, velocity-pressure decoupling is achieved in conjunction with the approximate factorization. Main emphasis is placed on the additional decoupling of the intermediate velocity components with only n th time step velocity The temporal second-order accuracy is Preserved with the approximate factorization without any modification of boundary conditions. Since the decoupled momentum equations are solved without iteration, the computational time is reduced significantly. The present decoupling method is validated by solving the turbulent minimal channel flow unit.

• 대한한약신문
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• s.119
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• pp.1-8
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• 2007

2007년도 지부별 정기총회 성료/'약방의 감초' 농가재배 길 열려/제1차 한약 등 약물부작용 관련 전문가회의/2007년도 지부장 간담회 개최/의료비연말정산 관련 실무협회의/자매결연비 제막식 가져/식약청, 한약재 품질평가 연구회 20일 창립/성형.보약도 소득 공제 내년 11월까지 한시 적용/'한방화장품 국제 경쟁력강화 정책 세미나' 개최/서울약령시 한의약문화축제 5월 31일 개막/식의약청 용역과제 관련 전문가 자문회의/한방기능성 섬유 국제적 관심 중국상하이 국제 섬유박람회/한약재수급조절위원회 개최/기성한약서 10종으로 개정돼야/'제7회 산청한방약초 축제'/"제35회 보건의 날" 기념행사 개최/한의사-한조약 '한방파스' 놓고 논쟁/제38대 한의협회장 경선 2파전/충북, 제51회 정기총회.연수교육 실시/충남, 제45회 정기총회 개최/부산, 제45회 정기총회 개최/광주, 제21회 정기총회 개최/전남, 제49회 정기총회 개최/대전, 제19회 정기총회 개최/경기, 제47회 정기총회 개최/경북, 제49회 정기총회 개최/경남, 제45회 정기총회 개최/지부탐방-지부장에게 듣는다/우리 약초를 찾아서-자귀나무

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.290-293
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• 2004

Recently, injection molded plastic optical products are widely used, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique measuring birefringence in optical plastic parts using R-G-B separation of white light. The main idea of an analysis comes from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. A complete system to give the quantitative values of retardation covering high order 2-D birefringence will be demonstrated. Further investigation is under way to improve the accuracy of the system using diodes as light sources.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.04a
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• pp.383-388
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• 2010

1999년 씨랜드 청소년 수련원 화재로 19명이 사망하여 샌드위치 패널의 위험성이 대두되었으며, 2008년도 이천 냉동창고 화재 그리고 최근 2009년 11월 19일에도 샌드위치 패널로 건축된 물류창고에서 화재가 발생하였다. 이러한 샌드위치 패널로 시공된 물류창고 등의 화재는 확대가 빠르므로 난연재 소재의 샌드위치 패널의 필요성에 대한 관심이 높아져 가고 있다. 따라서 본 연구에서는 폴리스티렌 폼을 심재로 한 샌드위치 패널의 장점에 난연성을 부과하여 화재 안전성을 도출하는 하고자 한다. 샌드위치 패널의 심재로 주로 사용되어지는 EPS 비드에 저가의 물유리를 코팅하여 난연성을 도출하고자 한다. 2차 발포 성형시에 물유리가 고온의 스팀에 씻겨 내려가지 않고 남아서 난연성을 나타내도록 하는 것이 목표이다.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.2
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• pp.62-70
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• 2001

As the ship hull is a compound-curved structure, plate bending process is indispensible. The process includes press bending process for forming major 1st curvature and heating process for forming the rest curvature. Especially the heating process that is above 50 percents of entire bending work is carried out exclusively by skillful workers. Many researches have been made to automate the heating process but most of these are about line heating process and researches for triangle heating process are rare. This study is a fundamental study to develop a efficient analysis method for triangle heating and focused on clarifying the deformation characteristics of plate by triangle heating. In this paper, we carried out heating experiments and analysed the deformation characteristics of plate to explain the deformation characteristics of plates rationally by showing the phase transformed high temperature region. Also we investigated the heating effect on the hull material properties by mechanical tests.

• The korean journal of orthodontics
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• v.29 no.3 s.74
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• pp.285-301
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• 1999

There is a need for more accurate prediction in surgical orthodontic treatment. Video imaging is an important technology in planning orthognathic surgery and educating patients about the esthetic results after treatment. Preoperative and postoperative lateral cephalogram of 30 patients who had one piece Le Fort I osteotomy advancement and mandibular set back by bilateral intraoral vertical ramal osteotomy with or without genioplasty were used in this study. The computer generated soft tissue line drawing prediction were compared with the actual postoperative cephalograms .The results are as follows. 1. 14 variables showed Statistically significant differences from 24 variables between computer predicted profile and post operative profile 2. Most of the differences were found in the maxilla-related soft tissue landmarks. 3. The predicted results were more accurate in the groups who had small amount of mandibular set back. 4. The predicted results were more accurate in the groups who had no genioplasty. Most of these differences were within 2mm ranges. Therefore profile change prediction by video imaging could be considered clinically acceptable.