• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.134-135
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• 2003

인체안의 단색수차는 시력의 한계를 규정하고 또한 안광학 기기의 설계에 있어서 중요한 요소이기 때문에 오래 전부터 많은 관심을 갖게 되었다. 또한 단색수차를 정밀하게 측정함으로써 가장 이상적인 시력 교정 방법을 찾을 수 있다. 본 연구에서는 먼저 그림 1과 같은 Shack-Hartmann (SH) 파면분석기를 구성하였다. 이 파면분석기는 대물렌즈, 결상렌즈, 미소렌즈배열(microlens array, MLA), 그리고 이미지 센서(CCD)로 구성되어 있다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.158-159
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• 2003

본 논문에서는 레이저 빔의 파면을 고속으로 정밀하게 측정하기 위한 신호처리 알고리즘을 연구하였다. 레이저 빔의 파면 정보는 Shack-Hartmann 센서 내부의 CCD 카메라에 획득되는 점영상으로부터 기울기 정보를 추출하여 구할 수 있다. 컴퓨터는 영상처리 보드를 이용하여 하트만 센서 내부의 카메라에 획득되는 영상을 양자화된 디지털 값으로 획득한 후 이를 컴퓨터 메모리에 저장한다. 하트만 센서 내부의 CCD 카메라에 촬상되는 레이저 빔 영상은 CCD 픽셀들에 의하여 이산 샘플링되고, 이 영상은 컴퓨터 내부에 장착된 영상처리 전용 보드에 의하여 양자화된 디지털 값으로 변환된다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.72-73
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• 2003

시력 진단장비로는 자각식 측정법인 시력표, 타각식 계측기로는 검영기와 자동굴절력측정기 등이 있으나 눈도 일반 광학계와 같이 공간적으로 불균일한 광학적 특성을 가지기 때문에 눈의 광학적 기능을 정확하게 진단하기 위해서는 광학수차의 공간 분포를 정밀하게 측정할 필요가 있다. 광학수차는 시력의 한계를 규정하고 안광학 기기의 설계에 있어서 중요한 요소이다. 눈의 광학수차를 측정하기 위한 파면분석기에는 공간분해굴절계, Tscherning 파면분석기, 광선추적파면분석기, 주사실틈굴절계, 그리고 Shack-Hartmann 파면분석기(SH 파면분석기) 등이 있으며, SH 파면분석기는 적응광학계에서도 유용하게 사용되고 있다. (중략)

• Journal of Chest Surgery
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• v.28 no.11
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• pp.963-966
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• 1995

Ischemia reperfusion injury occurs in various diseases. The role of oxygen free radicals in IR injury of the lung has been spotlighted and many studies have been performed. In this study, we tried to prepare a stable rat lung model for IR injury, focusing on surrounding conditions as hilar stripped left lung, clamped left pulmonary artery and bronchus,and declamped after determined period was passed, and right main pulmonary aretery was clamped. Arterial blood gas analyes were performed at 1, 10, 20, 30, minutes after reperfusion. Before clamping, PaO2 was 95 to 120 mmHg in all animals. There were six groups; Group I : temperature 15o C, and 120 minutes clamping, Group II: 20 oC, and 120 minutes clamping, Group III : 25 oC, and 120 minutes clamping, Group IV : 15oC, 90 minutes clamping, Group V : 20 oC, 90 minutes clamping,Group VI: 20 oC, 75 minutes clamping. Each groups contained 10 Sprague Dayley rats. The humidity was maintained 100 % as circulation imerged isotonic Hartmann`s solution of the pleural cavity. In group IV, V, and VI, PaO2 decreased significantly in all animals immediately after reperfusion, but 43 % survived till 10 minutes after reperfusion, it was 74.0$\pm$5.7, 73.3$\pm$10.8,and 88.2$\pm$17.7 mmHg. Pulmonary edema was observed histologically in 2/10 animals in group IV, 6/10 in group V , 3/10 in group VI, 9/10 in group I, and the other lungs showed all edema. We established a stable model by setting ischemic time,and temperature, between 75 to 90 minutes,15 to 20o C, and isotemperature Hartmann`s solution immersion of the pleural cavity.

• Annals of Coloproctology
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• v.34 no.6
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• pp.317-321
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• 2018

Purpose: We evaluate the role of transanal tube drainage (TD) as a conservative treatment for patients with anastomotic leakage (AL). Methods: Patients treated for AL who had undergone a low or an ultralow anterior resection with colorectal or coloanal anastomosis for the treatment of rectal cancer between January 2013 and January 2017 were enrolled in this study. The data were collected prospectively and analyzed retrospectively. The primary outcomes were the diagnosis and the management of AL. Results: Two hundred thirteen consecutive patients, 122 males and 91 females, were included. The mean age was $66.91{\pm}11.15years$, and the median body mass index was $24kg/m^2$ (range, $20-35kg/m^2$). The median tumor distance from the anal verge was 8 cm (range, 4-12 cm). Ninety-three patients (44%) received neoadjuvant therapy for nodal disease and/or locally advanced rectal cancer. Only 13 patients (6%) developed AL. Six patients developed subclinical AL as they had a defunctioning ileostomy at the time of the initial procedure. They were treated conservatively with TD under endoscopic guidance in the endoscopy unit and received intravenous antibiotics. Six weeks after discharge, these 6 patients underwent follow-up flexible sigmoidoscopy which showed a completely healed anastomotic defect with no residual stenosis. Seven patients developed a clinically significant AL and required reoperation with pelvic abscess drainage and Hartmann colostomy formation. Conclusion: These results suggest that TD for management of patients with AL is safe, cheap, and effective. Salvaging the anastomosis will help decrease the need for Hartmann colostomy formation. Proper patient selection is important.

• Korean Journal of Optics and Photonics
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• v.28 no.3
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• pp.108-115
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• 2017

We report the assembly procedure and performance evaluation of a visible and near-infrared spectrometer in the wavelength region of 400-900 nm, which is later to be combined with fore-optics (a telescope) to form a f/2.5 imaging spectrometer with a field of view of ${\pm}7.68^{\circ}$. The detector at the final image plane is a $640{\times}480$ charge-coupled device with a $24{\mu}m$ pixel size. The spectrometer is in an Offner relay configuration consisting of two concentric, spherical mirrors, the secondary of which is replaced by a convex grating mirror. A double-pass test method with an interferometer is often applied in the assembly process of precision optics, but was excluded from our study due to a large residual wavefront error (WFE) in optical design of 210 nm ($0.35{\lambda}$ at 600 nm) root-mean-square (RMS). This results in a single-path test method with a Shack-Hartmann sensor. The final assembly was tested to have a RMS WFE increase of less than 90 nm over the entire field of view, a keystone of 0.08 pixels, a smile of 1.13 pixels and a spectral resolution of 4.32 nm. During the procedure, we confirmed the validity of using a Shack-Hartmann wavefront sensor to monitor alignment in the assembly of an Offner-like spectrometer.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.13 no.1
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• pp.1-11
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• 2013

The determination of the pose of the imaging camera is a fundamental problem in computer vision. In the monocular case, difficulties in determining the scene scale and the limitation to bearing-only measurements increase the difficulty in estimating camera pose accurately. Many mobile phones now contain inertial measurement devices, which may lend some aid to the task of determining camera pose. In this study, by means of simulation and real-world experimentation, we explore an approach to monocular camera localization that incorporates both observations of the environment and measurements from accelerometers and gyroscopes. The unscented Kalman filter was implemented for this task. Our main contribution is a novel approach to landmark initialization in a Kalman filter; we characterize the tolerance to noise that this approach allows.

• Journal of Chest Surgery
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• v.10 no.2
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• pp.250-267
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• 1977

Open heart surgery has been performed on 20 patients, using hemodilution principle under the moderate hypothermia from Dec. 1975 through Aug. 1977 at the Department of Thoracic and Cardiovascular Surgery, Kyungpook National University School of Medicine. All these patients, body surface area ranged from 0.53 to 1.67$M^2$, were divided into two groups as a child group [below 15 yrs] and a adult group[above 15 yrs]. The oxygenator were primed with fresh ACD blood, 5 per cent dextrose, Hartmann`s solution, 15 per cent mannitol, sodium bicarbonate, dexamethasone and antibiotics. The average flow rate was 2.0 L/$M^2$/min. in child group and 2.3L/$M^2$/min. in adult group. The degree of hemodilution in child and adult group was 30.7% and 29.3% respectively. The minimal value of rectal temperature was $30.84{\pm}0.7^{\circ}C.$, in child group and $30.0{\pm}1.5^{\circ}C.$, in adult group. We studied the changes of hemodynamic status, blood components, electrolyte, acid-base status. blood lactic acid and urine output during and after cardiopulmonary bypass.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.1
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• pp.23-31
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• 2011

An analysis has been conducted of the flow characteristics and pumping performance of a thermopneumatic micropump with electrically conducting fluid. In the present study, considered is a thermopneumatic micropump for electrically conducting fluids with electromagnetic resistance alternately exerted at the inlet and outlet by alternately applied magnetic fields. A model of Prescribed Deformation is used for the motion of the membrane. Here, the pumping performance of the micropump and flow characteristics of the electrically conducting fluid are investigated in the range of Hartmann number less than 30. The current numerical study shows that the net flow rate through the micropump is almost proportional to the strength of the applied magnetic field.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.188-189
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• 2000

원자력 산업에서는 레이저진동측정기와 같은 원격/비접촉 측정기술이 많이 사용된다. 가동 중인 연구용 원자로의 핵연료 진동측정 같은 경우도 이러한 원격측정기술이 요구되고 있으나, 측정 대상체가 유동하는 유체 안에 있으므로 입사한 레이저의 파면이 변형되어 레이저진동측정기의 적용이 어렵다. 적응광학계(adaptive optics system; 또는 능동광학계)는 유동 층에서 변형된 파면을 파면측정 센서로 측정하고, 변형거울(deformable mirror)등의 파면보정 장치를 사용하여 파면을 보정하는 기술이다. 본 연구에서는 Shack-Hartmann 파면측정센서를 개발하고, 변형거울과 파면측정센서를 컴퓨터에 연결하여 레이저 파면의 왜곡상태를 폐회로(closed-loop)로 보정하는 장치를 개발하였다. (중략)