• Journal of the Korean Society of Radiology
• /
• v.5 no.6
• /
• pp.401-407
• /
• 2011

The purpose of this study is to know the differences of MR spectra, obtained from normal volunteers by variable TE value, through the quantitative analysis of brain metabolites by peak integral and SNR between 1.5T and 3.0T, together with PRESS and STEAM pulse sequence. Single-voxel MR proton spectra of the human brain obtained from normal volunteers at both 3.0T MR system (Magnetom Trio, SIEMENS, Germany) and 1.5T MR system (Signa Twinspeed, GE, USA) using the STEAM and PRESS pulse sequence. 10 healthy volunteers (3.0T:3 males, 2 females; 1.5T : 3 males, 2 females) with the range from 22 to 30 years old (mean 26 years) participated in our study. They had no personal or familial history of neurological diseases and had a normal neurological examination. Data acquisition parameters were closely matched between the two field strengths. Spectra were recorded in the white matter of the occipital lobe. Spectra were compared in terms of resolution and signal-to-noise ratio(SNR), and echo time(TE) were estimated at both field strengths. Imaging parameters was used for acquisition of the proton spectrum were as follow : TR 2000msec, TE 30ms, 40ms, 50ms, 60ms, 90ms, 144ms, 288ms, NA=96, VOI=$20{\times}20{\times}20mm3$. As the echo times were increased, the spectra obtained from 3.0T and 1.5T show decreased peak integral and SNR at both pulse sequence. PRESS pulse sequence shows higher SNR and signal intensity than those of STEAM. Especially, Spectra in normal volunteers at 3.0T demonstrated significantly improved overall SNR and spectral resolution compared to 1.5T(Fig1). The spectra acquired at short echo time, 3T MR system shows a twice improvement in SNR compared to 1.5T MR system(Table. 1). But, there was no significant difference between 3.0Tand 1.5T at long TE It is concluded that PRESS and short TE is useful for quantification of the brain metabolites at 3.0T MRS, our standardized protocol for quantification of the brain metabolites at 3.0T MRS is useful to evaluate the brain diseases by monitoring the systematic changes of biochemical metabolites concentration in vivo.

• Korean Journal of Optics and Photonics
• /
• v.11 no.6
• /
• pp.400-404
• /
• 2000

All-optical clock recovery from a 10 Gb/s RZ signal has been demonstrated using an actively mode-locked figure-eight laser incorporating a semiconductor optical amplifier in the loop-mirror scheme. Optical pulses with 10 ps pulse width were modulated by a LiNb03 external modulator at $2^{23}-1$ PRES and injected into the clock recovery circuit to extract optical pulses with 12 ps width. Regeneration of the original bit pattern has been accomplished by modulating the recovered clock with the same modulator, and no power penalty was observed at $10^{11}$..

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.579-582
• /
• 2002

In acquiring the surface information of a part, two types of measuring machines have been used: contact type and non-contact type. Since each measuring device has the pres and cons, an integrated measuring system is proposed to acquire the optimal point data. In order to implement the integrated measuring system, the relationship of coordinate systems between each measuring device should be established. In this paper, a new datum fixture and a calibration method for the multiple-sensor measuring system are proposed. The datum fixture is designed to interface two machines, a CMM and a laser scanner. The position of the datum fixture is calibrated by the axis information off motorized rotation stage which is used for a part setup.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.92.1-92.1
• /
• 2011

고분자 전해질 연료전지 (PEMFC)의 핵심 부품 중의 하나인 Bipolar Plate (분리판)을 제조하기 위해서 고분자/그라파이트 복합재료를 사용하였다. 고분자 매트릭스로는 경화시 뛰어난 화학적, 기계적 특성을 갖는 에폭시를 채택하였고, 전기 전도성을 부여하기 위해 그라파이트를 도입하였으며, 에폭시 수지의 내충격성을 향상시키기 위해서 Carbon Fiber를 채택하였다. 에폭시 분말과 그라파이트 분말, 그리고 1cm 정도의 길이를 갖는 Carbon Fiber을 믹서에 넣고 균일하게 혼합하였다. 이 혼합물을 이형제 처리된 몰드에 주입하고, Hot Press를 사용하여 가열, 가압 ($150^{\circ}C$, 4 ton/$cm^2$, 2시간)하면서 경화시켰다. 일정 비율로 고정된 에폭시/그라파이트 계에 Carbon Filber의 혼합 비율을 변화시키면서 전기적, 물리적 성질의 변화를 연구하였다.

• Korean Journal of Food Science and Technology
• /
• v.20 no.5
• /
• pp.644-649
• /
• 1988

The inhibitory activities against bacterial ${\alpha}-amylase$of oriental drugs from animals, plant and mineral origin were investigated. In final screening test, it was found that Areca catechu L., Cinnamomum cassia Pres 1. and Ephedra sinica Stapf had stronger inhibitory activities against ${\alpha}-amylase$ than other oriental drugs used in this experiment.

• Computers and Concrete
• /
• v.18 no.3
• /
• pp.421-439
• /
• 2016

Corrosion of embedded reinforcing bars is recognized as being the major cause of deterioration of reinforced concrete structures. With regard to maintenance strategies of concrete nuclear structures, the monitoring of cracking remains of primary importance. Recently, authors have developed a post-treatment technique to extract crack features from continuous computations. In this paper, such technique is applied to carry out a numerical analysis of an accelerated corrosion test. Obtained results allow highlighting specific propagation and failure mechanisms that characterize corrosion-induced cracking.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2013.07a
• /
• pp.255-257
• /
• 2013

최근 OS와 개발 정보에 대한 일반 사용자들의 접근성이 좋아지면서 오픈소스(Open Source)와 관련 툴들이 각광 받고 있다. 이러한 툴 중 많은 사람들이 사용하고 있는 블로그 개발 툴의 하나인 워드프레스(WordPress)는 다양한 프로그래밍 언어와 플랫폼(platform), 브라우저(browser)에 구애 받지 않고 강력한 기능을 제공함으로써 web과 관련하여 이용 빈도가 늘어나고 있다. 따라서 본 연구에서는 오픈 소스 툴 중 하나인 워드프레스의 기능성을 중점적으로 서술하고 일반 사용자가 워드프레스를 사용할 때 가장 큰 어려움이 무엇인지 짚어보고 문제에 대한 해결책을 제시한다.

• Parasites, Hosts and Diseases
• /
• v.46 no.1
• /
• pp.41-43
• /
• 2008

The ruddy turnstone, Arenaria interpres interpres, a migratory Korean bird, was proved to be a natural definitive host for Gynaecotyla squatarolae (Digenea: Microphallidae). The ruddy turnstone was found dead at the seashore of Okgu-eup, Gunsan-si, Jeollabuk-do. The intestinal tract was examined, and 98 unknown flukes were recovered. The worms were $600{\times}284{\mu}m$ in size, and had 2 ventral suckers. The seminal vesicle was large, the genital atrium was prominent, and the average egg size was $20{\times}12.5{\mu}m$. Based on these results, the worms were identified as G. squatarolae. This is the first report on the ruddy turnstone as a natural definitive host of G. squatarolae in the Republic of Korea.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.10 no.2
• /
• pp.48-55
• /
• 2001

An accumulator in hydraulic systems stores kinetic energy during braking action, and then that control hasty surge pres-sure. This study suggests a method to select the capacity of accumulator to control surge pressure to a desired degree. The selection method is based upon a trial and error approach and computer simulation. A mathematical dynamic model of the system was derived and the parameters in the model were identified from experimental data. A series of computer simulation were done for the brake action. The results of the simulation work were compared with those of experiments. These results of the computer simular-tion and experiments show that the proposed method can be applied effectively to control the surge pressure of the hydraulic regenerative brake systems.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.11 s.176
• /
• pp.202-209
• /
• 2005

In this paper, benchmark tests of Rapid Prototyping(RP) are presented to evaluate characteristics of various RP Systems and Processes, and several decision-support systems are developed to select RP Machine/Process suitable to user's requirements. Results of the RP benchmark tests are applied to the recently developed RP machines for the purpose of analyzing attributes such as dimensional accuracy, surface roughness, build cost, build time, and etc. Decision-making support systems are also developed, which contain not only new LCE (Linear Confidence Equation) algorithm but also modified PRES and MDS algorithm. Those algorithms are proved to be effective in that reasonably acceptable results are obtained on several cases of different inputs.