• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.433-438
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• 2011

Purpose: To investigate the proper distance from patient to target when measuring refractive error using open view target type auto-refractor(OVTAR), it was compared refractive errors between by OVTAR using N-vision-K5001 auto-refractor and internal fixation target type auto-refractor(IFTAR) using Canon auto-refractor. Methods: 21 subjects(42 eyes) aged 22.2(${\pm}$3.4) years old who had over 1.0 of corrected visual acuity and no ocular disease were participated for this study. Noncycloplegic measurements of refractive error were performed using a IFTAR(RK-F1, Canon, Japan) and an OVTAR(N-vision-K5001, Shin-nippon, Japan). The distances from subjects to targets in using the open the view target type auto-refractor were 1 m, 3 m, 4 m and 6 m. The refractive errors were compared between by IFTAR and by 1 m, 3 m, 4 m and 6 m target distances respectively using OVTAR. Results: At 1 m fixation distance the mean of refractive errors for total subjects was not significantly different between by OVTAR(-2.75${\pm}$1.84 D) and by IFTAR(-2.95${\pm}$2.04 D)(p=0.06). However at 3, 4 and 6 m fixation distance refractive errors by OVTAR were significantly lower myopic refractive errors than by IFTAR(p<0.05). Conclusions: The distance from subject to fixation target is needed over 3 m for the measurement of refractive error using OVTAR even not to 5~6 m distance.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.173-185
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• 2001

The orthodontic osseointegrated titanium implant, a kind of intraoral skeletal anchorage can be an alternative to tooth-borne anchorage, in case that the conventional tooth-borne anchorage is not available or the anchorage is critical. This study was conducted to elucidate the effect of early loading on the osseointegration of the orthodontic titanium implant and the healing process of the impaired bone at the site of implant after removing it. In two adult beagle dogs24 osseointegrated titanium implants were inserted into the alveolar bone, with 12 implants placed in each dog. In dog1, 6 out of 12 implants were loaded with 200-300gm of force immediately after placing, and the remaining 6 implants were not loaded for 4weeks. In dog2, all 12 implants had healing period of 4weeks, and then were loaded with 200-300gm of force for another 4weeks. Following an observation period of 4 and 8 weeks, the animals were sacrificed. Then the implants and the surrounding bone of dog1 and dog2 were removed, respectively. Undecalcified sections along the long axis of implant were made and the degree of osseointegration was examined under the light microscope. The results were as follows. 1. In the histologic features of tissues around implants anchored in dog1, there was no difference between immediately loaded implants and unloaded implants. Immature woven bone was ingrowing into the thread spaces from the original compacta and in direct contact with the implant surface in part. 2. The premature loading just after 4weeks healing period did not halt the progress of the osseointegration between bone and implant surface. The woven bone around the implants was maturing into the lamellar bone which resembled the structure of the original compacta at the end of 8weeks observation period. 3. Most implants with the inflammed surrounding mucosa were lost or mobile. The mobile implants were encapsulated by fibrous connective tissue which separated the implant surface from the bone. 4. The impaired bone at the site of the implant failed to anchor was showing recovery without inflammatory reaction 2weeks after removing, with the immaure woven bone lined by active osteoblasts and osteoid. Based on the results of this study, the integration of this orthodontic implant seemed to be impaired by the inflammation of the tissue surrounding the Implant rather than by early loading on implant, and increased with time lapsed after placing the implant. The use of implant described in this report can be recommended as an orthodontic anchorage unit immediately after insertion under the careful control of orthodontic force applied and plaque.

• Journal of Chest Surgery
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• v.31 no.7
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• pp.718-721
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• 1998

The surgical closure of VSD in patient with severe pulmonary hypertension has been considered a difficult problem for surgeons, because sudden hemodynamic change after closure of the defect could bring on high perioperative mortality. Recently, it was reported that UVP(unidirectional valve patch), which allows some blood to flow from right to left in case of acute right heart failure, is effective in improving the postoperative hemodynamics after closing septal defects. This 42-year old woman had suffered from VSD for 20 years and recently complained of worsening exertional dyspnea for three months, and was diagnosed of a large VSD(2.0 cm in diameter) with severe pulmonary hypertension(116/38 mm Hg), equal to systemic arterial pressure. We could successfully close VSD with severe pulmonary hypertension using one UVP and the other UVP for the creative ASD to be prepared against possible acute right heart failure. She was discharged on the fourteenth postoperative day and has been well for twelve months with spontanenous closure of UVP patch at the ninth postopeative month.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.83-89
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• 2004

The electronic distance measurement instrument, first introduced in the 1950s has, since those early days, undergone continual refinement. Rapid advances in related technologies have provided lighter, smaller and more precise equipment. Understanding for the principle, the standardized observation technique and the precision of EDM instrument is mostly important to improve the quality and the reliability of by-product in the field of engineering and industrial surveying. Simple and accurate calibration is regularly and periodically necessary to maintenance the precision of EDM instrument. This paper describes the calculated example of zero error and scale error as a correction of EDM by applying the least square method to baseline observations. Here we deals also with the testing criteria for precision instrument testing according to different types of EDM instruments.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.94-94
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• 2003

위성체의 유기오염은 광학계 렌즈 등의 오염 민감 표면에 분자단위로 흡착되어 표면에 층을 이루며 존재하는 것으로 위성의 성능저하 및 임무실패를 야기할 수 있는 주요원인이 된다. 유기오염은 단순히 대기에 노출되는 것만으로도 발생할 수 있으며, 특히 고온 고진공 상태에서는 다른 표면들에서 outgassing된 물질들이 흡착될 수 있기 때문에 그 영향이 극대화 된다. 본 연구에서는 이러한 유기오염을 측정하기 위하여 청정실과 열진공챔버 내에 witness plate를 설치하고 이를 적외선분광장비로 분석하였다. 적외선 분광장비를 이용하여 ESA(European Space Agency) 문서를 기준으로 4가지 물질에 대하여 검교정을 수행하였고, 그 결과를 바탕으로 유기오염물을 정량분석 하였다. 또한 유기오염물질의 분별을 통해 보다 정확한 분석을 수행하기 위하여 GC-MS(Gas Chromatograph - Mass Spectrometer)를 사용하여 분석을 시도하였으며, 이를 국제 기준에 적용하기 위한 방안도 모색하였다.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.313-315
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• 2001

The power system automation, especially the substation automation is a major issue. so it has been widely studied each country in the world. Since the substation system includes lots of measuring devices. a lot of data and system information are transmitted to operators. The measured values usually have the error that results from the communication process, and it can degrade the reliability of estimated values. So. the detection and correction of measured values at a substation are important factors for substation automation. In this paper, we study the detection and col of measured values at the domestic 154kV/2 distribution substation of double bus structure study will be useful for expected economic dispatch measuring device's inspection and corr management by SCADA system operation, substation automation.

• The korean journal of orthodontics
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• v.28 no.2 s.67
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• pp.329-341
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• 1998

Sterilization has received much attention in orthodontic practices over the past several years. The present study was undertaken to investigate the effects of sterilization on the physical properties of orthodontic pliers-AEZ, Unitek, and Dentronix ligature cutters. This study was designed to examine the tips of ligature cutters before and after 200 and 400 sterilization cycles using the Bowmar RHT-1000, the Dentronix DDS-5000, and the Eschmann SES-2000. The tip surface and the fracture surface were observed with a scanning electron microscope. The microstructure was observed with an optical microscope. The hardness test was carried out with the mic개-Vickers hardness tester and the Rockwell C Scale hardness tester. The chemical composition was analyzed by energy dispersive X-ray spectrometer. The results of this study were as follows : 1. The number and the size of corrosion products on the tip surface and the proportion of cleavage planes in fractured specimen increased, but the hardness of the tip decreased in proportion to sterilization cycles. From these observations, it was considered that mechanical properities decreased in proportion to sterilization cycles. 2. The number and the size of chromium carbides increased in proportion to sterilization cycles. Coarse microstructure decreased mechanical properities. 3. The AEZ and Unitek ligature cutters were Fe-Cr stainless steels, but the Dentronix ligature cutter was Co-Cr alloy. There were many differences among manufactures, but the chemical composition was .not changed after sterilization cycles. 4. The tip edge of ligature cutter used in a clinic revealed microcracks with the SEM observation. Clinical experience confirmed that ligature cutters were gradually degraded by sterilization.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.543-551
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• 2018

Purpose : The purposes of this study were to evaluate the changes of intraocular pressure according to corneal ablation amount after corneal refractive surgery and the changes of intraocular pressure according to refractive errors before corneal refractive surgery. Methods : The mean age of adults who underwent LASIK corneal refractive surgery were $37.34{\pm}7.42years$, and 108 adults(48 males, 60 females) were participated in this study. Refractive errors, intraocular pressure, and corneal ablation amount were measured using an autorefractor, a noncontact tonometer, and an excimer laser. All test values were considered statistically significant when p<0.05. Results : The mean intraocular pressure before corneal refractive surgery was $15.08{\pm}2.60mmHg$ in males and $14.16{\pm}2.67mmHg$ in females. The decrease of intraocular pressure after corneal refractive surgery were 4.22mmHg in males and 3.61mmHg in females. Spherical equivalent power were $-3.89{\pm}2.17D$ in males and $-4.45{\pm}2.92D$ in females before corneal refractive surgery, and $-0.10{\pm}0.46D$ in males and $-0.04{\pm}0.46D$ in females after corneal refractive surgery. The corneal ablation amount after corneal refractive surgery were statistically significant, with $53.95{\mu}m$ in males and $61.26{\mu}m$ in females. There was significant correlation between corneal ablation amount and decrease of intaocluar pressure(r=0.2299, p<0.001). As the growth of corneal ablation amount in males, the decrease of intraocular pressure was significantly increased. As the growth of refractive error, the amount of decrease in intraocular pressure was also significant. The decrease of intraocualr pressure were $3.04{\pm}2.18mmHg$ in low refractive error, $4.10{\pm}2.16mmHg$ in middle refractive error, and $4.65{\pm}3.29mmHg$ in high refractive error. Conclusion : We found that intraocular pressure decreased after corneal refractive surgery by noncontact tonometer and the change of intraocular pressure which is an important index for glaucoma diagnosis, may affect the judgment of eye disease. We think that a preliminary questionnaire whether corneal refractive surgery is necessary for the measurement of intraocular pressure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.739-747
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• 2011

The paper presents implementation & evaluation of survey method with tilted transducer of Multi Beam Echo Sounder (MBES) to increase horizontal & vertical coverage over obstructed port environments with limited physical properties of MBES. Proposed method ($25^{\circ}$ titled transducer) have some discrepancy of bathymetric profiles between normal and tilting method, but we proved average difference is less than IHO Special Order requirements with survey data at port of Dong Ho Port, Masan, Korea. For horizontal mapping coverage of total survey area ($114,961m^2$), normal method covered 53%, $60,895m^2$ of total area but tilting method covered 75%, $5.933m^2$. It is 22% efficient than normal method with similar environments. For vertical mapping coverage of total vertical structure face ($7,421m^2$), normal method covered 14%, $1,046m^2$, proposed methods covered 60%, $4,450m^2$. And we adapt longitudal steel bar to validate MBES results, and provide calibration method with titled transducer of MBES.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.56.1-56.1
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• 2010

MIRIS(Multipurpose InfraRed Imaging System)는 과학기술위성 3호의 주 탑재체로서 2011년 발사예정인 다목적 적외선 카메라 시스템이다. MIRIS는 우주관측 카메라와 지구관측 카메라로 구성되어 있으며, 우주관측 카메라는 $0.9-2.0{\mu}m$ 영역에서 3.67 deg. x 3.67 deg. FOV로 우리 은하평면 survey 관측과 우주배경복사(CIB) 관측을 수행할 것이다. 현재 MIRIS는 비행모델 개발 마무리 단계에 있으며, 검교정 시험, 열-진공 시험, 진동 시험 등을 수행하고 나면 2010년 말 위성 본체와의 조립을 진행할 것이다. 우주관측 카메라는 궤도상에서 태양, 지구의 적외선 복사와 망원경과 검출기 주변에서 발생하는 열잡음을 줄이기 위해 냉각이 필요하며, 제한된 위성의 무게와 부피, 전력등의 요구조건들 때문에 망원경 및 구조체의 복사냉각(Passive Cooling) 방법을 선택하였다. Passive cooling으로 우주관측 카메라의 망원경이 200K 이하로 냉각되면, dewar에 설치된 소형 냉각기를 가동하여 적외선 센서를 80K로 냉각한다. 위성체 내벽과 우주관측카메라의 각 구조체들 사이의 복사를 차단하기위해 30층의 MLI를 적용 하였고, 각 구조체들간의 열전도를 최소화하기위해 GFRP supporter를 적용하였다. 이 실험은 천문(연)에서 자체 제작한 열-진공 챔버를 활용하여 진행하였으며, 이미 인증모델에 대한 passive cooling 실험을 두 차례 실시하였고, 그 실험 결과를 반영하여 최종 비행모델에 대한 실험을 수행하였으며, 그 실험 결과에 대해 논의 하고자 한다.