• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1320-1322
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• 1994

Photoisomerization characteristics of 4-octyl-4'-(5-carboxy-pentamethyleneoxy) azobenzene molecules (8A5H) were attained by measurement of absorbtion spectra. 8A5H in chroloform($6.0{\times}10^{-5}[M/l]$) shows trans to cis and cis to trans isomerization by irradiation of lights of 360[nm] and 450[nm] wavelength. From LB monolayer films of 8A5H, also the cis/trans photoisomerization was obtained and it has reversibility and memory characteristics. We are now trying to detect these properties of 8A5H electrically. On this paper, we investigated the structural changes of monolayer on the water surface by measuring the displacement current as a preliminary experiment. The measuring system was constructed at home-made Kuhn type LB(Langmuir-Blodgett) deposition apparatus. 8A5H solution was spreaded at the air-water interface and the currents induced by the dynamic behavior of molecules were measured when the molecules were pressed by barrier. The reversibility of displacement currents by compression and expansion was obtained from 8A5H molecules, which shows the compressed molecules have a tendency to disperse after the compression. From this experiment, we conclude that the behavior of molecules on water surface can be monitored electrically by using this current measuring method, and this method can also be applied to detect the photoisomerization of monolayers on water surface.

• 전기전자학회논문지
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• 제20권3호
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• pp.299-302
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• 2016

본 논문에서는 성능이 향상된 Stack Monitoring System을 설계한다. Stack Monitoring System의 증폭기(AMP)에 들어오는 펄스성 잡음을 차단하기 위하여, 차폐 및 전원부 임피던스를 낮추고 전원회로를 분리하여 노이즈를 차단한다. 신틸레이션 검출기 특성을 최대한 장치에 매칭하기 위한 가변 고전압, 이득(Gain), 상쇄(Offset), 한계(Threshold) 등을 설정 할 수 있는 제어부를 설계한다. 또한 300 ~ 1,500V의 가변 고전압 전원회로를 구성하여 다양한 신틸레이션 검출기에 적용가능 한 가변 전압 공급 장치를 설계한다. 성능이 향상된 Stack Monitoring System은 다종의 신틸레이션 검출기가 각각의 특성을 고려하여 동작하게 함으로서 효율적이고 높은 신뢰성을 보장한다. 개발된 Stack Monitoring System의 측정 불확도에 대하여 공인 시험기관의 장비를 사용하여 실험한 결과 우수한 성능을 나타내었다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2004년도 수소연료전지공동심포지움 2004논문집
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• pp.103-108
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• 2004

The present paper relates to an apparatus in which all carbonaceous material such as coal, oil, plastics and any substance having carbon atoms as part of its constituents are reformed(gasified) into syngas at temperature above $1,200^{\circ}C$(KR patent No.0391121, and PCT/KR2001/01717 and PCT/KR2004/001020). It comprises a single-stage reforming reactor without catalyst and a syngas burner as shown in Fig.2. syngas is combusted with $O_2$ gas in the syngas bunter to produce $M_2O$ and $CO_2$ gas with exothermic heat. Reaction products are introduced into the reforming reactor, reaction heat from syngas burner elevate the temperature of reactor above $1,200^{\circ}C$, and reaction products reduce carbonaceous material down to CO and $H_2$ gases. Reactants and heat necessary for the reaction are provided through the syngas burner only, Neither $O_2$ gas nor steam are injected into the reforming reactor. Reformer is made of ceramic inner lining and sst outer casing. Multiple syngas burners may be connected to the reforming reactor in order to increase the syngas output, and a portion of the product syngas is recycled into syngas burner. The present reformer as shown in Fig.2 is suitable to gasify carbonaceous wastes without secondary pollutants formed from oxidation. Further, it can be miniaturized to accompany a fuel cell system as shown in Fig.3 The output syngas may be used to drive a fuel cell and a portion of electrical power generated in a fuel cell is used to heat a compact reformer up to $1,200^{\circ}C$ so that gas/liquid fossil fuel can efficiently reformed into syngas. The fuel cell serves as syngas burner in Fig.2. The reformation reaction is sustained through recycling a portion of product syngas into a fuel cell and using a portion of electric power generated to heat the reformer for continuous operation. Such reforming reactor may be miniaturized into a size of PC, then you have a Personal Reformer(PR).

• Restorative Dentistry and Endodontics
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• 제7권1호
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• pp.25-31
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• 1981

One of the most important factors for successful endodontic therapy is an accurate length determination of physiological root apex. Some methods suggested for the measurement of root canal length, include digital-tactile sense and roentgenographic technique with measuring wire, scale and grid. But these methods do not derermine an accurate working length to physiological root apex. Recently electronic measuring devices are used to locate the physiological root apex in root canal length determination and these devices are accepted as an effective apparatus. The 89 patients (116 teeth, 144 canals) among the out-patients of Yonsei University Dental Infirmary, who had had an endodontic treatment in the Department of Operative Dentistry, were measured by the Root-Canal Meter$^{(R)}$ as an electronic device, and radiographs to determine the distribution and location of physiological root apex, then the following results were made: (1) Range of ${\pm}$1mm from the radiographic root apex were present in 88.88% (128 canals) of the subjects. (2) Physiological root apex and radiographic root apex were coincided in 31.94% (46 canals) of the subjects. (3) The actual length of the physiological root apex of the teeth were as follow; A : in the maxillary central incisor : 0.46mm B : in the maxillary lateral incisor : 0.44mm C : in the maxillary canine : 0.44mm D : in the maxillary 1st premolar : a) Buccal : 0.59mm b) Lingual : 0.34mm E : in the maxillary 2nd premolar : 0.54mm F : in the maxillary 1st molar : a) Mesio-buccal : 0.50mm b) Disto-buccal : 0.42mm c) Lingual : 0.56mm G : in the mandibular central incisor : 0.62mm H : in the mandibular lateral incisor : 0.45mm in the mandibular canine : 0.54mm J : in the mandibular 1st premolar : 0.47mm K : in the mandibular 2nd premolar : 0.34mm L : in the mandibular 1st molar : a) Mesio-buccal : 0.54mm b) Mesio-lingual : 0.31mm c) Distal : 0.37mm.

• Animal Bioscience
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• 제34권5호
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• pp.880-885
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• 2021

Objective: Omasum is an important site for the absorption of short chain fatty acids. The major route for the transport of acetate is via sodium hydrogen exchanger (NHE). However, a discrepancy in the symmetry of sodium and acetate transport has been previously reported, the mechanism of which is unclear. In this study, we investigated the possible role of carbonic anhydrase (CA) for this asymmetry. Methods: Omasal tissues were isolated from healthy sheep (N = 3) and divided into four groups; pH 7.4 and 6.4 alone and in combination with Ethoxzolamide. Electrophysiological measurements were made using Ussing chamber and the electrical measurements were made using computer controlled voltage clamp apparatus. Effect(s) of CA inhibitor on acetate and sodium transport flux rate of Na22 and 14C-acetate was measured in three different flux time periods. Data were presented as mean±standard deviation and level of significance was ascertained at p≤0.05. Results: Mucosal to serosal flux of Na (JmsNa) was greater than mucosal to serosal flux of acetate (JmsAc) when the pH was decreased from 7.4 to 6.4. However, the addition of CA inhibitor almost completely abolished this discrepancy (JmsNa ≈ JmsAc). Conclusion: The results of the present study suggest that the additional protons required to drive the NHE were provided by the CA enzyme in the isolated omasal epithelium. The findings of this study also suggest that the functions of CA may be exploited for better absorption in omasum.

• 대한금속재료학회지
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• 제50권12호
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• pp.907-911
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• 2012

High purity silicon can be obtained from Al-Si alloys by a combination of solvent refining and centrifugation. Silicon purification by crystallization of silicon from an Al-Si alloy melt was carried out using 2N and 4N purity aluminum and 2N purity silicon as raw materials. The effect of the purity of raw materials on the final silicon ingot purity by centrifugation was investigated for an Al-50 wt% Si alloy. Alloys were melted using an electrical resistance furnace, and then poured into a centrifuging apparatus. A silicon lump like foam was obtained after centrifugation and was leached by an acid in order to get pure silicon flakes. Then silicon flakes were melted to make a silicon ingot using an induction furnace. The purities of the silicon flakes and silicon ingot were enhanced significantly compared to those of the raw materials of silicon and aluminum. The silicon ingot made of 4N aluminum and 2N silicon showed the lowest impurities.

• 한국지반공학회논문집
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• 제25권8호
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• pp.5-21
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• 2009

암반에 근입된 현장타설말뚝의 주면마찰력에 대한 최근의 연구결과에 따르면 주면마찰력은 암석의 일축압축강도 외에 굴착면의 거칠기, 암반의 재료특성, 초기 수직음력, 말뚝의 직경, 암반의 절리 및 풍화도 등에 크게 영향을 받는 것으로 보고되어 있다. 지금까지 개발된 굴착면 거칠기 시스템들은 공기 중에서만 측정가능하므로 현장의 굴착공내에서 직접 측정하는 것은 불가능하였다. 따라서, 본 연구에서는 수중에서 사용가능한 굴착공 벽면거칠기 측정 시스템(BKS-LRPS)을 개발하였으며, 특수 제작된 보정장치를 통하여 여러 가지 경우에 대한 검증을 수행하였다. 연구결과에 의하면, 개발된 BKS-LRPS는 장치제작조건 및 현장조건을 반영하도록 계획된 검증조건들에 대하여 유효측정영역을 제시할 수 있었다.

• Korean Journal of Acupuncture
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• 제40권4호
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• pp.194-205
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• 2023

Objectives : This study investigated the current utilization status of thermotherapy devices in Korean medicine (KM) institutions and identified areas for improvement and further development, as perceived by KM doctors (KMDs). Methods : An online survey was conducted, targeting KMDs primarily engaged in clinical patient care. The questionnaire included items about respondents' clinical practices, the extent of thermotherapy device usage, their opinions on these devices, and perceived improvement needs. The collected data underwent quantitative analysis. Results : From the 1,025 respondents, data from 862 respondents who provided complete responses were analyzed. On average, respondents utilized thermotherapy treatments for 80% of their patients. Infrared (IR) phototherapy unit, electrical moxibustion apparatus, and heater-based thermotherapy devices were predominantly owned by respondents, with IR being the most frequently used. The average satisfaction score for current thermotherapy devices was 79. A significant concern raised was the necessity for improved health insurance coverage and efficacy evaluation. Conclusions : This research has confirmed that the extensive use of thermotherapy devices by KMDs in treating primarily musculoskeletal and gastrointestinal ailments - common conditions among patients in KM institutions. The main areas identified for improvement encompass safety, cost-effectiveness, and device efficacy. Future enhancements in thermotherapy devices should address these crucial aspects.

• 한국안광학회지
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• 제14권4호
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• pp.65-69
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• 2009

목적: 최근 컴퓨터가 대량 보급되면서 VDT 증후군이 점차적으로 증가하고 있다. VDT 증후군은 VDT 작업자들에게 나타나는 근골격계 질환, 신경정신계 장애, 눈의 긴장, 피로, 자극과 충혈 등 안과적 증상을 포함한다. VDT 증후군의 환경요인으로는 전자파, 컴퓨터 화면의 크기, 밝기, 조명, 모니터 및 작업대의 높낮이, 작업시간, 작업의 종류, 작업자와 스크린과의 거리, 실내습도 및 온도, 사무실내의 공기오염, 환기 등이 있다. 본 연구에서는 근거리 시각 작업으로 인한 VDT 증후군에서 나타나는 주요 신체증상 및 신체 및 심리적으로 영향을 줄 수 있는 환경적 요인을 조사하였다. 방법: 연구대상자는 19세부터 28세사이의 남자 54명, 여자 66명으로 총 120명이었다. 책이나 문서 읽기, 컴퓨터 작업 등에 대한 근거리 작업을 할 때에 나타나는 신체적 증상과 육체적 불편함을 설문지를 이용하여 조사하였다. 조사항목에는 근업작업에 따른 주요 신체 증상과 눈의 자각 증상, 작업환경에 대한 만족도, 키보드, 마우스 사용시의 손목 통증 경험 등을 포함하였다. 결과: 장시간 컴퓨터, 문서, 전자기기를 사용할 때에 대부분(70%)이 신체적인 통증을 느끼는 것으로 나타났다. 통증부위는 주로 목과 허리(57.1%), 눈(45.2%), 두통(31%) 등이었다. 환경적 요인에서는 적절치 못한 조명으로 눈의 통증을 호소하는 사람들이 78.3%였다. 대부분의 증상은 '눈의 피로'(38.3%), '눈의 건조성'(31.9%), '눈의 흐릿함'(23.7%)이었다. 대상자들은 의자에 대한 불편함을 호소하였고 키보드, 마우스 사용 때 손목의 통증은 대부분 경험하였다. 결론: 전자기기, 문서 등을 이용할 때 빛, 공간, 자세, 작업대 등의 다양한 환경적 요인들이 조화롭지 못해 눈의 피로, 신체적인 피로감을 느낄 수 있다. 따라서 문서작업을 할 때에는 휴식시간에 대한 자기관리와 같은 예방법을 개발하여 눈의 피로를 줄여야 할 것이다. 또한 지속적인 연구를 통해 근골격계 질환 예방을 위해 최적의 시각적인 환경을 위한 인간공학적 디자인으로 작업환경을 바꾸어야 할 것이다.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.104-111
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• 2018

본 논문은 무급유식 공기 압축기가 널리 확산됨에 따라 영구자석형 동기 모터를 이용한 고효율 공기 압축기의 센서리스 제어에 관한 논문이다. 공기 압축기는 특성상 위치 센서를 설치하기 어려운 문제를 가지고 있다. 영구자석형 동기모터를 가변속 제어하기 위해서는 회전자의 위치를 파악하기 위한 위치센서가 필수적이다. 따라서 영구자석형 동기모터를 압축기에 활용하기 위해서는 센서리스제어가 필수적이다. 센서리스제어 방식으로 널리 사용되고 있는 역기전력을 통한 위치추정방식은 정지좌표계의 사용으로 인한 위상지연으로 인한 위치오차가 발생하게 되거나, 동기좌표계의 사용으로 인한 과도상태에서 추정역기전력이 오차를 포함하여 발산의 문제 등이 발생되는 문제가 있다. 따라서 본 논문에서는 회전각 추적 관측기를 사용하여 위치와 속도를 추정하고 외란 관측기를 통하여 속도의 리플을 저감시키는 방안을 제시하였다. 프리스케일사의 MPU를 이용하여 실험장치를 구성하고 구현실험을 통하여 제안한 알고리즘의 타당성을 검토하였다. 일정 시점에서 위치오차를 강제로 주더라도 위치보정 값이 위치오차 값을 찾아가며 추정위치가 실제 벡터 위치로 수렴해감을 검증하였다.