• 한국정밀공학회지
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• 제14권12호
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• pp.114-120
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• 1997

For compensating the error motion of hydrostatic tables, we have introduced a way that the clearance of table is controlled corresponding to the amount of eror with the actively controlled variable capillary, named as ACC. In previous paper, through the basic test, it was confirmed that by the use of ACC, the error motion within 2.7$\mu$ m of a hydrostatic table could be compensated with the resolution of 27nm, 1/100 contollable range, and with the frequency bandwidth of 5.5Hz, structurally. In this paper, we performed practical compensation of the linear and angular motion error of hydrostatic table using ACC. For improving the compensated motion accuracy, iterative control method is put into the control system. The experimental results show that by the simultaneous compensation of error, the linear and angular motion error are improved upto 0.25$\mu$ m and 0.4arcsec, which are about 1/10 and 1/3 of the non-compensated motion errors respectively.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2009년도 학술대회
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• pp.664-668
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• 2009

초고해상도 디스플레이 솔루션의 하나인 네트워크 타일드 디스플레이는 프로세싱(디코딩, 렌더링)과 디스플레이가 분산되어 존재하여 동시에 많은 실시간으로 미디어를 프로세싱하여 가시화 할 수 있다. 하지만 현재 구조상 사용자는 각 미디어를 프로세싱하고 디스플레이 하기 위해 요구되는 자원과 각 프로세싱 하는 머신에서 가용한 자원을 사전에 알고 적절한 프로세싱, 디스플레이 머신을 직접 선택해야 한다. 이러한 절차를 간소화 하고자 본 논문에서는 미디어와 네트워크 타일드 디스플레이를 구성하기 위해 필요한 자원을 분석하고 이를 바탕으로 새로운 미디어를 가시화하고자 할 때 동적으로 프로세싱 하는 머신에 자원을 할당하는 방법을 제시하고자 한다. 또한 제안된 방법을 실제 네트워크 타일드 디스플레이에 적용하여, 본 방법의 타당성을 구현 결과를 통해 확인하고자 한다.

• Journal of Korean Neurosurgical Society
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• 제38권2호
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• pp.111-115
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• 2005

Objective : Upper lumbar disc herniation is rare disease, compared with lower. The lamina of this high level lumbar vertebra is narrower than that of low level, and this have taken surgeon into important consideration for surgical methods because partial removal of lamina for discectomy weakens the base of the articular process and may result in fracture. The authors an accurate preoperative diagnosis that enables the surgeon to operative approach for preserving the facet joint. Methods : Thirteen patients with upper lumbar disc herniation have underone surgical procedure by midline approach for removal of ruptured disc fragment and paraspinal approach for removal of residual disc materials simultaneously without instrumentation. All patients who underwent surgery were analyzed and long-term follow-up was conducted. Results : At a mean follow-up of 24months, there were complete resolution of presenting radiating leg pain in 85% of the patients, 7.5% were left with minimal residual discomfort, and 7.5% derived little or no benefit from surgery. The follow-up radiologic findings of all patients shows that lamina and facet joint have preserved safely and no instability. Conclusion : Simultaneously, paraspinal with midline approach provides highly satisfactory operating methods by simplifying exposure and greatly limiting the risk of complications. This provides the basis for a planned surgical approach in which destruction of the facet joint can be avoided.

• 천문학회보
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• 제41권2호
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• pp.38.1-38.1
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• 2016

TRAO has been newly equipped with a multi-beam receiver system, 16 pixel MMIC preamplifiers in a $4{\times}4$ array, a FFT spectrometer, and new control computer systems. In our new receiver systems one can make simultaneous observations with two molecular lines maximum 15 GHz apart with a spectral band width of 60 MHz. Typical system temperatures are about 160 - 200 K at 86 ~ 100 KHz and 400 - 500 K at 115 GHz in the dry weather. The new systems using On-The-Fly mode were found to be very efficient in making quick and sensitive maps of large clouds with a high velocity resolution (~0.04 km/s at 100 GHz). TRAO now calls for proposals for 2016 and 2017 observing season for everybody. In the talk we will introduce the current status of TRAO upgrade and its scientific preliminary results.

• 천문학회보
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• 제41권2호
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• pp.41.1-41.1
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• 2016

The Galactic center, Sagittarius A* (Sgr A*), is the closest supermassive black hole and emits synchrotron radiation. It provides great opportunity to study the origin of mm/sub-mm emission. Currently, two competing models have been suggested as a jet base and a radiatively inecient accretion flow (RIAF). To unveil the properties, the extremely high resolution(${\sim}10{\mu}as$) corresponding to the projected Schwarzschild radius of ~0.1AU is necessary. With KVN, a jet model can be tested by multi- frequency simultaneous observations because the optically thick surface in a jet (i.e. radio core) moves toward the center at a higher frequency. We conducted 8 observations with KVN at 43/86GHz in 2015, and found that the measured positional shift to the reference calibrator, J1744-3116, was ~0.3 mas to the south of Sgr A* using the source frequency phase referencing (SFPR) at Q/W bands for the first time. With the result, in the future, we will attempt to measure the variation of source position shifts that can constrain the direction of approaching jets and the variability of black hole activity of Sgr A*.

• 한국기계가공학회지
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• 제16권3호
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• pp.100-106
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• 2017

A universal outer diameter measurement module was developed using a linear variable differential transformer (LVDT). This outer diameter measurement module enables simultaneous measurement of outer diameter, displacement, and perpendicularity of bench-type high-precision products by combining analogue and digital measurement principles with mechanically precise and fine adjustment functions. The developed module showed a performance of 0.001mm in measurement resolution, 0.001mm in measurement accuracy, reference surface abrasion lower than Ra 0.1864, and measurement stability of 0.002mm. Therefore, we have acquired domestic measurement technology to improve productivity by securing technical competitiveness for universal diameter measurement technology, lower production costs through import substitution, and increased quality of products with more precise measurement technology. Furthermore, a substitution effect is expected for expensive import measurement system equipment used in production, research, and inspection sites in industries that produce precision processing products such as automobile and machine components.

• 한국정밀공학회지
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• 제30권2호
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• pp.177-184
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• 2013

This paper proposes an enhanced Simultaneous Localization and Mapping (SLAM) algorithm based on matching laser image and Extended Kalman Filter (EKF). In general, laser information is one of the most efficient data for localization of mobile robots and is more accurate than encoder data. For localization of a mobile robot, moving distance information of a robot is often obtained by encoders and distance information from the robot to landmarks is estimated by various sensors. Though encoder has high resolution, it is difficult to estimate current position of a robot precisely because of encoder error caused by slip and backlash of wheels. In this paper, the position and angle of the robot are estimated by comparing laser images obtained from laser scanner with high accuracy. In addition, Speeded Up Robust Features (SURF) is used for extracting feature points at previous laser image and current laser image by comparing feature points. As a result, the moving distance and heading angle are obtained based on information of available points. The experimental results using the proposed laser slam algorithm show effectiveness for the SLAM of robot.

• 한국식품위생안전성학회지
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• 제13권1호
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• pp.41-46
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• 1998

HPLCdp 의한 주요 afltoxins(aflatoxins $B_1,\;B_2,\;G_1\;및\;G_2$)의 동시 분석에서 postcolumn 유도체화법을 시도하였다. Electrochemical cell (Kobra-cell)을 사용한 postcolumn 유도체화법은 기존의 precolumn 유도체화법보다 분석시간을 단축하였으며 (약 1/2 단축), 더 안전하고 , 향상된 분석능을 보였다. Aflatoxin $B_1과\;G_1의$ 경우 10~100ppb에서, 그리고 B_2와\;G_2의$ 경우 3~30 ppb에서 직선성을 나타내었다. Aflatoxin $B_1과\;G_1은$ 각각 88.9% 및 100.5%로 양호한 회수율을 보였다. Aflatoxin $B_2와\;G_2의$ 경우 분리도는 우수하였으나 회수율에있어서 변이가 크게 나타났다.

• 조명전기설비학회논문지
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• 제19권3호
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• pp.119-126
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• 2005

Electrical resistance tomography(ERT)는 적절하게 설계된 전류를 대지 지하에 주입하여 이에 따른 인가전압을 대지 경계에서 측정한 후 이를 근거로 ERT의 영상복원 알고리즘에서 대지 지하의 대지저항률 분포를 얻고 대지 지하에 뭍힌 물체를 크기와 위치, 그리고 저항률에 대한 특성을 파악할 수 있는 기술이다. 본 논문에서는 ERT의 영상복원 기법으로 Gauss-Newton, TLS와 SIRT 방법들을 살펴본다. 컴퓨터 시뮬레이션을 통해 TLS 방법을 이용한 ERT 영상복원의 성능이 Gauss-Newton와 SIRT방법에 의해 얻어진 결과보다 향상되는 것을 보이도록 한다.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.449-453
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• 2009

A mesoporous assembly of layered titanate with well-dispersed Pt cocatalysts has been synthesized via a restacking of exfoliated titanate nanosheets and a simultaneous adsorption of Pt nanoparticles. According to powder X-ray diffraction analysis, the obtained mesoporous assembly shows amorphous structure corresponding to the disordered stacking of layered titanate crystallites. Field emission-scanning electron microscopy and $N_2$ adsorption-desorption isotherm measurement clearly demonstrate the formation of mesoporous structure with expanded surface area due to the house-of-cards type stacking of the titanate crystallites. From high resolution-transmission electron microscopy and elemental mapping analyses, it is found that Pt nanoparticles with the size of ~2.5 nm are homogeneously dispersed in the mesoporous assembly of layered titanate. In comparison with the protonated titanate, the present mesoporous assembly of layered titanate exhibits better photocatalytic activity for the photodegradation of organic molecules. This finding underscores that the restacking of exfoliated nanosheets is quite useful not only in creating mesoporous structure but also in improving the photocatalytic activity of titanium oxide.