• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권5호
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• pp.396-401
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• 1999

In this study, $Ar^+$ ion laser etching process of single/poly-crystalline Si with $CCl_2F_2$ gas is investigated for MEMS applications. In general, laser direct etching process is useful in microelectronic process, fabrication of micro sensors and actuators, rapid prototyping, and complementary processing because of the advantages of 3D micromachining, local etching/deposition process, and maskless process with high resolution. In this study, a pyrolytic method, in which $CCl_2F_2$ gasetches molten Si by the focused laser, was used. In order to analyze the temperature profile of Si by the focused laser, the 3D heat conduction equation was analytically solved. In order to investigate the process parameters dependence of etching characteristics, laser power, $CCl_2F_2$ gas pressure, and scanning speed were varied and the experimental results were observed by SEM. The aspect ratio was measured in multiple scanning and the simple 3D structure was fabricated. In addition, the etching characteristics of $6\mum$ thick poly-crystalline Si on the insulator was investigated to obtain flat bottom and vertical side wall for MEMS applications.

• 한국표면공학회지
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• 제53권6호
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• pp.330-342
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• 2020

Since the original report on ferroelectricity in Si-doped HfO2 in 2011, fluorite-structured ferroelectrics have attracted increasing interest due to their scalability, established deposition techniques including atomic layer deposition, and compatibility with the complementary-metal-oxide-semiconductor technology. Especially, the emerging fluorite-structured ferroelectrics are considered promising for the next-generation semiconductor devices such as storage class memories, memory-logic hybrid devices, and neuromorphic computing devices. For achieving the practical semiconductor devices, understanding polarization switching kinetics in fluorite-structured ferroelectrics is an urgent task. To understand the polarization switching kinetics and domain dynamics in this emerging ferroelectric materials, various classical models such as Kolmogorov-Avrami-Ishibashi model, nucleation limited switching model, inhomogeneous field mechanism model, and Du-Chen model have been applied to the fluorite-structured ferroelectrics. However, the polarization switching kinetics of fluorite-structured ferroelectrics are reported to be strongly affected by various nonideal factors such as nanoscale polymorphism, strong effect of defects such as oxygen vacancies and residual impurities, and polycrystallinity with a weak texture. Moreover, some important parameters for polarization switching kinetics and domain dynamics including activation field, domain wall velocity, and switching time distribution have been reported quantitatively different from conventional ferroelectrics such as perovskite-structured ferroelectrics. In this focused review, therefore, the polarization switching kinetics of fluorite-structured ferroelectrics are comprehensively reviewed based on the available literature.

• 동의생리병리학회지
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• 제38권2호
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• pp.59-65
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• 2024

Rectal prolapse is a condition where the rectal wall protrudes outside the anus. While it is a rare condition, it can cause discomfort for patients due to the protrusion of the rectal structure, discharge of mucus and blood, fecal incontinence, constipation, and other inconveniences. In this review, we analyzed a randomized controlled trial (RCT) study that used the herbal medicine Bojungikgi-tang(Buzhongyiqi-tang) as a complementary therapy to improve the weaknesses and side effects of the standard treatment, surgical therapy, for rectal prolapse. The analysis included 12 RCT studies, and in all studies, the prescription involved the use of Astragali Radix at the highest dosage. Among the 11 studies that evaluated efficacy, 7 studies showed a significant effect compared to the control group. In all 3 studies that evaluating recurrence rates and all 5 studies investigating complications after surgery, the experimental group showed significant effects. Based on these findings, this study could be considered as a foundational evidence for the application of bojungikgi-tang(Buzhongyiqi-tang) in clinical practice in Korean medicine for patients with rectal prolapse. It could also serve as foundational data for future research.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.1-6
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• 2002

How is the flow in a rotating impeller. About 35 years have passed since one experimentalist rotating with the impeller. of a huge centrifugal blower made the flow measurements using a hot-wire anemometer (Fowler 1968). Optical measurement methods have great advantages over the intrusive methods especially for the flow measurement in a rotating impeller. One is the optical flow visualization (FV) technique (Senoo, et al., 1968) and the other is the application of laser velocimetry (LV) (Hah and Krain, 1990). Particle image velocimetries (PIVs) combine major features of both FV and LV, and are very attractive due to the feasibility of simultaneous and multi-points measurements (Hayami and Aramaki, 1999). A high-pressure-ratio transonic centrifugal compressor with a low-solidity cascade diffuser was tested in a closed loop with HFC134a gas at 18,000rpm (Hayami, 2000). Two kinds of measurement techniques by image processing were applied to visualize a flow in the compressor. One is a velocity field measurement at the inducer of the impeller using a PIV and the other is a pressure field measurement on the side wall of the cascade diffuser using a pressure sensitive paint (PSP) measurement technique. The PIV was successfully applied for visualization of an unsteady behavior of a shock wave based on the instantaneous velocity field measurement (Hayami, et al., 2002b) as well as a phase-averaged velocity vector field with a shock wave over one blade pitch (Hayami, et al., 2002a. b). A violent change in pressure was successfully visualized using a PSP measurement during a surge condition even though there are still some problems to be overcome (Hayami, et al., 2002c). Both PIV and PSP results are discussed in comparison with those of laser-2-focus (L2F) velocimetry and those of semiconductor pressure sensors. Experimental fluid dynamics (EFDs) are still growing up more and more both in hardware and in software. On the other hand, computational fluid dynamics (CFDs) are very attractive to understand the details of flow. A secondary flow on the side wall of the cascade diffuser was visualized based either steady or unsteady CFD calculations (Bonaiuti, et al.,2002). EFD and CFD methods will be combined to a hybrid method being complementary to each other. Measurement techniques by image processing as well as CFD calculations give a huge amount of data. Then, data mining technique will become more important to understand the flow mechanism both for EFD and CFD.

• 건축역사연구
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• 제18권2호
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• pp.47-63
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• 2009

This study focused on changes in form and spatial uses of Urban Hanok in Bukchon, Seoul. There are 10 representative cases which have been renovated through the policy of 'Preservation & Regeneration of Bukchon' by Seoul metropolitan government and other experts. Changes in form and spatial uses of Urban Hanok in Buckon are as follows. First, Changes of scale. Trough removing extension parts, facade of renovated Hanoks are 'transformed' into recovering their identity. Using basements or lofts, intensive application of spaces is transformation which promotes the vitality of Hanoks. Second, changes of space organization. As Hanok changes its function from residence to commercial or cultural use, il a1so changes space character or reorganizes space organization. It is important that deciding function of Hanok has to adjust its scale and organization. Third, changes of construction performance. Through introducing new material and constructing method, performance of wall has been changed respecting its wooden structure and interior-exterior figure. However, technical studies must back it up not to destroy its value of eco-friendly architecture. Fourth, changes of facility systems, like floor heating system. They changes floor level of Hanok equally, and then sections of Hanok have became simple. Furthermore, inserting new facility space, such as boiler room, stand-up kitchen, bathroom and toilet, organization of space also changed. It is necessary that wise alternative proposal through the method of transformation or mutation must be presented. These four changes can be classification into method of 'transformation' and 'mutation'. Changes of scale are method of transformation and changes of space organization are method of mutation. Also, while changes of construction performance are mutation, changes of facility systems are transformation. Recently, as price of lots have been increased, a lot of Hanoks have been commercialized. Thc commercial energy threat 'the identity of Bukchon as residential area'. From now on, to operate 'identity' and 'vitality' complementary, it is necessary to make up for the preservation policy of Hanok and consolidate renovating standards of Hanok which correspond to character of particular region and building usage.

• 지질공학
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• 제30권1호
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• pp.17-30
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• 2020

광학영상화검층은 광원과 CMOS 영상 센서를 이용하여 시추공벽을 이미지로 구현하는 물리검층 기술로 지하의 불연속면에 대한 여러 가지 원위치 정보를 고분해능으로 제공한다. 최근 시추공영상화검층은 지반침하 모니터링, 암반 무결성 평가, 응력으로 인한 단열 변화 탐지, 극지에서의 빙하 연대측정 등 그 활용범위가 매우 다양해졌다. 현재 국내외로 많이 이용되고 있는 시추공영상화검층 시스템은 장비 사양에 따라 한계점을 가지고 있어 적용 범위에 대한 검증과 여러 가지 시추공 환경에 대한 적절한 품질관리가 필요하다. 그러나 광학영상화검층의 자료로 도출되는 이미지는 원위치 정보로 정확도, 구현도, 신뢰성에 대한 검증에 직접적인 비교 확인이 어렵다. 본 논문에서는 신뢰성 있는 고품질 자료 취득 방법과 자료 처리 방법을 확인하기 위해 시추공 환경과 유사한 모듈화 된 균열모형시추공을 설계·제작하여 현재까지 보고되지 않은 실험에 대한 결과를 얻고자 하였다. 검출기 자기계 방향 확인의 정확성을 검증하고, 노출시간에 따른 색상의 구현도 및 균열의 분해능 관계, 정확한 간극 측정을 위한 자료 처리 방법 등을 제시하였다. 다양한 시추공 환경을 모사한 균열모형시추공 실험을 통해 고분해능의 신뢰성 높은 광학영상화검층의 자료 취득 및 해석이 가능할 것으로 기대된다.

• 한국지반공학회논문집
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• 제24권8호
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• pp.25-34
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• 2008

연약 지반의 거동 특성 평가를 위하여 전단파 속도와 전기저항을 측정할 수 있는 새로운 압밀셀을 개발하였다. 전단파의 발진과 수신을 위한 벤더엘리먼트는 압밀셀의 상 하부판 및 벽면에 설치하였다. 국부적인 간극비 변화를 평가하기 위하여 이중 쐐기 형식의 전기저항 탐침을 적용하였다. 벤더 엘리먼트와 전기저항 탐침은 나일론 재질의 스크류 안에 고정하였다. 나일론 재질의 스크류는 압밀셀과의 임피던스 차이로 인하여 압밀셀을 통한 파의 직접적 전달을 최소화하며, 고장난 벤더 엘리먼트와 전기저항 탐침을 쉽게 교환하게 해준다. 전기저항-대수 시간 곡선의 기울기 및 전단파 속도의 변화로부터 일차 압밀 시간을 평가하였다. 교란 효과가 적을 경우, 입자 배열은 전단파 속도에 영향을 미치며 이로부터 흙의 고유 이방성을 평가할 수 있었다. 압밀 실험동안 침하량으로 산정한 간극비와 전기저항으로부터 계산된 간극비는 거의 유사한 것으로 나타났다. 본 연구는 전단퐈 속도와 전기저항이 일차 압밀, 고유 이방성, 간극비 등 연약 지반의 압밀 특성 파악을 위한 보완적인 정보를 제공해 줌을 보여준다.

• Parasites, Hosts and Diseases
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• 제24권2호
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• pp.159-170
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• 1986

1984년 1월부터 1986년 6월까지 30개월간, 확진된 뇌 유구낭미충증 환자 69명에 대하여 혈청학적 추적검사를 실시하였다. 환자는 모두 치료전에 뇌전산화 단층 촬영을 실시하였고 효소면역측정법에 의하여 혈청 및 뇌척수액의 특이 IgG 항체가를 측정하였다. 프라지콴텔에 의한 약물 치료는 $3{\times}25mg/kg$의 용량으로 $4{\sim}14$일간 실시하였다. 추적기간 및 회수는 환자마다 달랐으며 최대 추적기간은 22개월이었다. 추적검사용 혈청 및 뇌척수액은 $-40^{\circ}C$에 보관한 후 낭액항원, 낭벽항원 및 두절항원에 대한 IgG 항체가를 일시에 측정하였다. 프라지콴텔 투여후 $1{\sim}4$개월 사이에 환자의 대부분에서 혈청 및 뇌척수내 특이 IgG 항체가는 일시적으로 상승하였다. 치료 직후부터 항체가가 저하하는 환자가 있었으나 소수이었다. 프라지콴델 투여시의 부작용을 줄이기 위해 덱사메타손을 투여하면 항체가 상승은 억제되었다. 프라지콴텔 치료후 혈청내 항체가 평균치의 변동이 뇌척수액내 항체가 평균치의 변동보다 심하였고, 항체가의 변화율은 낭벽항원이나 두절항원에 대한 항체에서 낭액항원에 대한 항체에서 보다 컸으나 항체가 변동폭은 낭액항원에 대한 항체가 더 컸다. 대상 환자 69명중 혈청학적으로 음성이었던 6명중 1명은 치료후 뇌척수액내 낭액항원에 대한 항체가가 양성범위로 전환하였다. 프라지콴텔 투여후 항체가의 상승은 뇌 유구낭미충증의 혈청학적 진단에서 보조적으로 이용할 수 있다고 생각하였으며 추적기간으로는 투여후 1개월이 적합하다고 생각하였다. 치료후 6개월내지 22개월까지 추적검사한 환자 15명중 혈청과 뇌척수액에서 모두 음성으로 전환한 예는 1례뿐이었고 혈청이나 뇌척수액 어느 하나에서라도 음성으로 전환한 예도 3례에 불과하였다. 만성 경과를 취한 심한 뇌 유구낭미충증 환자에서의 혈청학적 음성전환은 관찰 기간중 없었다. 추적 검사증 급성 뇌염증상이 나타난 만성환자에서는 일시적으로 두절항원에 대한 항체가가 상승하고 있었다. 이상의 결과에서 뇌 유구낭미충증 환자를 프란지콴텔로 치료한 다음 면역효소측정 법으로 혈청학적 추적검사를 실시할 경우 투약후 매 1년에 한번씩 실시하면 완치된 환자를 감별할 수 있을 것으로 생각하였다.