• 한국정밀공학회지
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• 제19권4호
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• pp.195-201
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• 2002

We propose a new scheme of high-resolution heterodyne interferometer that employs the two-axial mode He-Ne laser with an inter-mode beat frequency of 600~1000 MHz. An electronic RF-heterodyne circuit lowers the beat frequency down to 5 MHz, so that the phase change of the interferometer output is precisely measured with a displacement resolution of 0.1 nanometer without significant loss of dynamic bandwidth. A thermal control scheme is adopted to stabilize the cavity length with ainus to suppress frequency drifts caused by the phenomena of frequency pulling and polarization anisotropy of the two-axial made laser to a stability level of 2 parts in $10^9$. The two-axial mode HeNe laser yields a high output power of 2.0 mW, which allows us to perform multiple measurements of up to 10 machine axes simultaneously.

• 천문학논총
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• 제19권1호
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• pp.109-119
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• 2004

As a core project of the Korean Astronomical Data Center (KADC) in Korea Astronomy Observatory (KAO), we have constructed a framework of astronomical database using MySQL and JSP. MySQL database server is a powerful open source database management system, and JSP technology provides a simplified, fast way to create dynamic web content. Combined together, MySQL and JSP enable us to develop server-independent web-based applications efficiently in a short amount of time. The MySQL tables and JSP programs embedded in our database are built/written in a way to benefit both users and managers. We plan to expand our database by supplementing additional data in the near future. Our newly constructed database is expected to be the prototype of the Korean Virtual Observatory (KVO).

• 천문학회보
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• 제42권1호
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• pp.57.2-57.2
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• 2017

Remote and robotic telescopes are the most effective instrument for astronomical survey projects. The system is based on the dynamic operation of all astronomical instruments such as dome and telescope control system (TCS), focuser, filter wheel and data taking camera. We adopt the ASCOM driver platform to control the instruments through the integrated software. It can convert different interface libraries from various manufacturers into a uniform standard library. This allows us to effectively control astronomical instruments without modifying codes. We suggest a conceptual design of software for automation of a small telescope such as the new wide-field 0.25m telescope at McDonald Observatory. It can also be applied to operation of multi-telescopes in future projects.

• 한국콘텐츠학회논문지
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• 제7권12호
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• pp.283-291
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• 2007

유비쿼터스 컴퓨팅의 시대로 접어들면서, 컴퓨터 시스템은 언제 어디서나 우리의 일상생활에서 필요로 하는 적절한 서비스와 정보를 제공할 수 있게 되었다. 이러한 유비쿼터스 컴퓨팅은 언제 어디서나 학습을 할 수 있는 유비쿼터스 학습의 개념으로 발전시켰다. 본 논문에서는 기존의 ERSS(Korea's Educational Resources Sharing System)를 발전시켜, 유비쿼터스 컴퓨팅 기술이 적용된 U-스쿨을 위한 프레임워크를 제안한다. 제안된 프레임워크는 기존의 ERSS를 기반으로 하여 모바일 기술, 센서 단말 기술과 상황 인식 기술을 적용하였고 사용자 중심의 시나리오를 사용하여 사용자 중심의 러닝 환경을 제공한다. 특히 유비쿼터스 교육 환경에서의 상황인식 서비스는 학생, 교사, 객체 및 환경의 동적인 상황 정보를 기반으로 즉시 학습 및 개인별 맞춤 학습에 적용될 수 있다.

• 대한기계학회논문집A
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• 제33권5호
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• pp.489-495
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• 2009

A novel technique to measuret of viscoelastic properties of polymers is proposed to investigate complex Poisson's ratio as a function of frequency. The forced vibration responses for the samples under the normal and the shear deformation are to be measured with varying load masses. The measured data were used to obtain the viscoelastic properties of the material based on an accurate 2D numerical deformation model of the sample. The 2D model enabled us to exclude data correction by the empirical form factor used in 1D model. Comprehensive measurements of viscoelastic properties of two slightly varied silicone RTV rubber ($Silastic^{(R)}$ S2) compositions were performed. Standard composition (90% PDMS polymer + 10% catalyst) and modified composition (92.5% polymer + 7.5% catalyst) were tested in temperature range from $30^{\circ}C$ to $70^{\circ}C$. Shear modulus, modulus of elasticity, loss factor, and both the real and the imaginary parts of the Poisson's ratio were determined for frequencies from 50 to 400Hz in the linear deformation regime (at relative deformations $10^{-4}{\sim}10^{-3}$).

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1989년도 춘계학술대회
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• pp.29-34
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• 1989

300 MHz proton NMR spectra of human blood plasma were analyzed by deconvolution of spectrum, and we compared its results with Fossel's test in normal (15 cases), liver cancer (14 cases) , and other cancer (14 cases) groups. This analysis had enabled us to obtain dynamic characteristics of each individual lipoprotein. As a result of deconvolution method, the VLDL and chylomicron intensity level were found to be elevated in the patients with liver cancer. Moment ratio values of $CH_2$ resonance in the raw spectrum were found to be higher than the normal group for patients with, malignant tumors other than liver cancer. These differences between the three groups could not be found in the conventional Fossel's test. We could simulate plasma spectra by addition of spectra of individual lipoproteins through deconvolution method. Further clinical trials in larger populations and additional biochemical method may shed new light on many of clinical and biochemical interests for knowing characteristics about lipoprotein not separated from blood and the background of Fossel test.

• 한국압력기기공학회 논문집
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• 제13권2호
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• pp.51-59
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• 2017

Steam jets ejected from a rupture zone of high energy pipes may cause damage to adjacent structures. This event could lead to more serious accidents in nuclear power plants. Therefore, to prevent serious accidents, high energy pipes of nuclear power plants are designed according to the ANSI / ANS 58.2 technical standard. However, the US Nuclear Regulatory Commission (USNRC) has recently pointed out non-conservatism in existing high energy pipe fracture evaluation methods, and required the assessment of the unsteady load of the jet caused by a potential feedback mechanism as well as the impact range of steam jet, the jet impact loads and the blast wave effects at the initial breakage stage. The potential feedback mechanism refers to a phenomenon in which a vortex formed by impingement jets amplifies vortex itself and induces jet vibration in a shear layer. In this study, CFD methodology using the LES turbulence model is established and numerical analysis is carried out to evaluate the dynamic behavior of impingement jets and the potential feedback mechanism during jet impingement. Obtained results have been compared with an empirical correlation and experiment.

• 패션비즈니스
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• 제24권4호
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• pp.48-62
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• 2020

Originating in South Korea, Taekwondo has been globally popular among individuals who desire to improve their health in a unique fashion. The Taekwondo uniform, one of the essential factors within the sport, needs to possess both functionality and size suitability to support dynamic movements within Taekwondo. This study investigated the development of patterns in Taekwondo uniforms by suggesting patterns that reflect physical suitability derived from appearance tests and movement functionality tests of the uniforms. More specifically, we selected a sample uniform and conducted a dressing test, which considered both the aesthetics and the functionality of the garment. Then, we considered size suitability, which allowed us to design practical Taekwondo uniform patterns that encompassed more variation in body sizes of both men and women. The result of the dressing test was that women's uniforms typically required more factors compared to men's uniforms due to women's relatively smaller physiques. Based on this result, we revised the pattern to also encompass the minor differences in uniforms between men and women. In the end, the Taekwondo uniforms for women required more modifications than those for men.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.164-171
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• 2003

The side impact behavior has been investigated when the high strength steel 60TRIP(Transformation Induced Plasticity) is replaced for the conventional low-carbon steel for weight reduction of an auto-body. The side impact analysis was carried out as specified in US-SINCAP with the center pillar and the side sill of the conventional steel or 60TRIP. For accurate impact analyses, the dynamic material properties are adopted with the Johnson-Cook model. The analysis results demonstrate that the penetration of the side members is remarkably reduced when 60TRIP is employed for the center pillar and the side sill replacing the conventional steel. The crashworthiness in the side impact is considerably improved with less penetration of the side members and less acceleration of the opposite floor.

• KIEAE Journal
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• 제16권2호
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• pp.33-41
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• 2016

Purpose: The window energy rating system was developed in early 1990's and various kind of rating system has been implemented in advanced country such as Europe, Australia, Canada and the US since 2000. In Korea, the Energy Consumption Efficiency Rating Indication System has been implemented to promote supply of high efficiency window since July 2012. Normally, the window energy rating system based on heat balance which considers both thermal losses and solar heat gain is used and applied only to residential buildings. However, the system used nationally only considers thermal losses and is applied to every building regardless of its usage. Therefore, in this study, we indicated problems of domestic window energy rating system and looked for improvements. Method: We analyzed thermal performance of various windows through dynamic simulation applied to detached house and compared results with those of domestic and foreign rating system. Result : Thermal performance of south windows is more affected by SHGC than U-value, and that of north windows is also affected by SHGC a lot. The difference between the results of our study and current system is statistically significant. As a result, appropriate evaluation criteria which considers solar heat gain is required.