• 공업화학
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• 제10권7호
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• pp.985-989
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• 1999

유기 실란화합물을 사용하여 실리카($SiO_2$)박막을 감압 유기금속 화학증착법(LPMOCVD)으로 제조하였다. 원료로는 triethyl orthosilicate(TRIES)를 사용하였다. 실험조건은 반응기의 출구압력을 1~100 torr, 반응온도는 $600{\sim}900^{\circ}C$로 하였다. 높은 반응온도와 원료농도에서는 $SiO_2$가 빠른 성장속도를 나타내었다. 마이크로 스케일 트랜치에서 층덮임이 좋게 나타났는데, 이것은 응축된 다량체들이 트랜치쪽으로 유동하는 현상 때문으로 생각되었다. 원료가스가 중합반응을 하여 다량체(2량체, 3량체, 4량체 등)들이 생성되고, 그 다량체들이 확산하여 고체표면에서 응축되는 반응경로를 따를 것으로 추정된다. 반응관의 출구에서 기상중의 화학종들을 사극질량분석기로 분석한 결과, 반응온도 $650{\sim}700^{\circ}C$에서는 단량체, 원료가스의 2량체, 고분자들의 피크가 관측되었다. 고온($900^{\circ}C$)에서는 거의 모든 원료가스와 중간체(중합된 다량체) 분자들이 산화되었거나 차가운 관벽에 응축되어 고분자들의 피크가 없어졌다.

• Journal of Chest Surgery
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• 제10권2호
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• pp.195-204
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• 1977

Dynamic lung compliance was measured in healthy ten young[mean age, 26 years] male and five young[mean age, 25 years] female. Lung volume was integrated of the rate of flow signal which was obtained by using pneumotachograph and differential pressure transducer[PM 5, Statham]. Intrapleural pressure was measured as that of intraesophagel pressure. Esophageal ballon, 15. 5cm in length, 4ml of luminal capacity and made of thin latex, was connected to the polyethylene tube that had 12-14 side holes and was of 1.5mm of ID. Transpulmonary pressure was traced by means of differential pressure transducer[PM 131, Statham] to which connected the esophageal balloon catheter and connection tube from mouth piece. Lung volume and transpulmonary pressure were photographed by cathode ray oscilloscope camera while the subjects were breathing spontaneously. Dynamic lung compliance loop was displayed on single trace monitor and subtraction was performed for the quasi-static hysteresis. Dynamic lung compliance was measured, 1. by plotting the pressure-volume relationship 2. from the subtracted pressure-volume loop. Results were as follows. 1. Dynamic lung compliances measured by plotting of healthy young male and female were $0.202{\pm}0.06$ and $0.190{\pm}0.023L/cm$ $H_2O$ respectively. 2. When measured from subtraction loop, dynamic lung compliance for male and female were $0.327{\pm}0.107$, and $0.27{\pm}0.06L/cm$ $H_2O$ respectively. 3. Dynamic chest wall and total respiratory system compliance were also measured. 4. Dynamic lung compliance by plotting appeared to be essentially same when compared to that of static compliance reported previously from our laboratory, however, that obtained from subtraction loop revealed higher values than the compliances obtained by plotting and that of static compliance.

• 한국수정란이식학회지
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• 제25권4호
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• pp.259-262
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• 2010

Optimization of the preimplantation mammalian embryo culture condition was widely focused on refining medium composition under the name of chemically defined media. However, recent research revealed that the alteration of physical environment can be a crucial factor to a successful embryo development. In this study, under the same embryo density, a novel culture device named oil-free micro tube culture (MTC) system was evaluated using porcine parthenogenetic embryos. The activated oocytes were placed into the 0.2 ml thin-wall flat cap PCR tube and cultured to the blastocyst stage. As a preliminary step, embryo density and culture medium volume were optimized under a standard drop culture system. The optimal embryo density range for in vitro culture was 0.5 embryos per ${\mu}l$ in $20\;{\mu}l$ drop (20.5%) and 1.0 embryos per ${\mu}l$ in $10\;{\mu}l$ drop (20.6%). Based on these results, we compared drop culture system and 'MTC' system in terms of the developmental rate to the blastocyst stage. In $20\;{\mu}l$ medium volume, the 'MTC' system showed similar blastocyst formation rate when compared with drop culture system (20.2% versus 20.5%, respectively) while the 'MTC' system showed lower blastocyst formation rate than drop culture system in $10\;{\mu}l$ one (12.7% versus 20.0%, respectively). Therefore the $20\;{\mu}l$ MTC system may be an alternative incubation system for short-distance embryo transport without carrying the $CO_2$ incubator and this provides novel embryo culture device to clinical veterinary embryologists.

• 한국진공학회지
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• 제12권1호
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• pp.70-77
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• 2003

전이금속을 촉매로 이용하여 화학기상증착법 (CVD)으로 탄소나노튜브 (CNT)를 성장시킬 때, 질소분위기가 성장을 증진시킨다는 사실은 잘 알려져 있다. 본 논문에서는 질소분위기에 의한 CNT 성장증진의 원인이 활성화 질소이며, 활성화 질소가 성장과정 중 CNT의 탄소와 결합함으로써 성장증진효과가 일어남을 보여주었다. 이 결과는 질소의 결합이 튜브상의 흑연판을 만드는데 필요한 탄성변형에너지를 낮추어 주는 역할을 한다는 CNx 박막의 이론적 계산결과와 일치한다. 따라서, 질소의 결합에 의한 CNT의 성장증진 효과는 튜브상의 흑연판 핵 생성과 CNT의 성장에 필요한 임계 에너지의 감소에 의한 것이다.

• 한국융합학회논문지
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• 제10권12호
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• pp.129-134
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• 2019

의료기관에서 많이 사용되는 방사선 차폐 재료인 납을 대처할 수 있는 플라스틱 제품으로 PVC를 선택하였다. 방사선 차폐 의복 이외에 저선량 영역에서 의료기기 부품, 산업용 차폐 재료로 사용이 가능한지 평가하고자 한다. 상업용 PVC는 밀도가 3.68 g/㎠ 으로 재료의 유연성과 경제성 등 일정 방사선 영역에서는 충분한 차폐 효과를 긍정적으로 기대할 수 있으며, 다양한 형태로 변형이 가능하고, 경량의 차폐벽으로 사용할 수 있다. 의료기관에서 임상 검사 시 사용되는 의료방사선 영역 대에서 3mm PVC 5장을 두께로 조절하여 차폐 성능을 실험하였다. 의료방사선의 관전압 기준으로 실효에너지에 대한 차폐 성능을 평가하였다. PVC는 두께가 두꺼울수록 관전압과 실효에너지가 낮을수록 차폐효과는 크게 나타났으며, 차폐효과는 12mm 두께에 관전압 80kVp에서 70%의 차폐효과가 있었다. 따라서 PVC 재료의 차폐효과는 두께의 의존율이 높게 나타났다. 앞으로는 차폐 성능을 높이면서 얇고 가벼운 친환경 제품을 만들기 위한 지속적인 연구가 필요하다.

• Parasites, Hosts and Diseases
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• 제55권5호
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• pp.541-548
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• 2017

A survey was performed to know the infection status of echinostome metacercariae in Cipangopaludina chinensis malleata snails from Korea. Total 75 snails collected in 5 localities, i.e., Imsil-gun, Jeollabuk-do, Hwasun-gun and Shinan-gun (Aphae and Jido), Jeollanam-do, and Jinju-si, Gyeongsangnam-do, were examined for metacercariae by the artificial digestion method. Infection rates of metacercariae were 80.0%, 66.7%, 100%, 60.0%, and 73.3%, and their densities were 39, 32, 183, 19, and 30 per snail infected, respectively. The metacercariae were round, $105-118{\times}105-118{\mu}m$ in size, with a thin cyst wall, collar spines on the head collar, and excretory granules in 2 canals of excretory tube. Adult flukes were elongated, ventrally curved, and $5,167{\times}939{\mu}m$ in average size. Head collar distinct, bearing 45 collar spines with 5 end groups on each side. Oral sucker subterminal, pharynx well developed, and esophagus somewhat short. Cirrus sac well developed, with a saccular seminal vesicle, and ventral sucker very large. Ovary elliptical and on the median line of the body. Testes tandem and slightly lobed. Eggs operculated, elliptical, and $90-103{\times}55-60{\mu}m$ in size. By scanning electron microscopy, the head collar was prominent with 45 collar spines resembling horns of younger stags. Scale-like tegumental spines were densely distributed on the body surface between the head collar and ventral sucker. Conclusively, it has been first confirmed that the life cycle of E. macrorchis is indigenously maintained in Korea, and C. chinensis malleata snails are popularly infected with the metacercariae of this echinostome.

• Corrosion Science and Technology
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• 제7권5호
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• pp.283-287
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• 2008

The drag reduction agency (DRA) for gas pipeline, a novel method used for reducing friction or drag on a gas flowing to increase the transmission efficiency of gas pipeline, is a more flexible and economical technology than internal flow efficient coatings. In this paper, an effective DRA has been developed in Authors' Institute by analyzing the hydrodynamic friction resistance on internal gas pipeline and then studying the work mechanism and molecular structure of DRA. In the meantime, a group of property test for selecting DRA material has been determined, including viscosity, contact angle, volatility, corrosion, slab extending, and flow behavior in horizontal tube. The inhibition efficiency and drag reduction efficiency of the developed DRA have been investigated finally based on the relevant test methods. Results of corrosion test show that the developed DRA has very good inhibition effect on mild steel by brushing a thin layer of DRA on steel specimens, giving inhibition efficiency of 91.2% and 73.1% in 3%NaCl solution and standard salt fog environment respectively. Results of drag-reducing test also show that the Colebrook formula could be used to calculate friction factors on internal pipes with DRA as the Reynolds number is in the range of $0.75\times10^5\sim2.0\times10^5$. By comparing with normal industrial pipes, the friction resistance coefficient of the steel pipe with DRA on internal wall decreases by 13% and the gas flux increases by 7.3% in testing condition with Reynolds number of $2.0\times10^5$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.435-435
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• 2010

A inclined slot-excited plasma source is newly designed and constructed for higher flux HNB(Hyperthermal Neutral Beam) generation. The present source is different from the vertical SLAN(SLot ANtenna) sources [1] in two aspects. One is that the slots are inclined, and the other is that the magnetic field is configured to a cusp type. These modifications are intended to make the source plasma operated in sub-milli-torr pressure regime and as thin as possible, both of which is to get higher HNB flux by decreasing the re-ionization rate of the reflected atoms from the neutralizer [2]. The plasma is generated in a quartz tube of internal diameter 170 mm enclosed in a aluminum application chamber of larger diameter 250 mm. The microwave power is fed to the plasma chamber by 8 inclined slots cut into the application chamber wall. The slots are coupled the chamber to a WR280 waveguide wound around it to form a ring resonator. In order to make two slots $\lambda_g/2$ apart in phase, the adjacent slots are rotated in opposite directions. The rotation angle of the slots are set to $60^{\circ}$ from the chamber axis. Between the quartz chamber and the aluminum cylindrical chamber 8 NdFeB magnets are equally spaced and fixed to form the cusp magnetic field confinement and ECR (Electron Cyclotron Resonance) field. In this presentation, the magnetic and electromagnetic simulations, and the measured plasma parameters are given for both the inclined and the vertical slot-excited plasma sources. We also discuss how the sources can be tailored to suit better-performing HNB sources.

• 한국지반공학회논문집
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• 제24권5호
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• pp.79-87
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• 2008

최근에 벤더 엘리먼트를 이용한 현장탄성파 프로브(probe, MudFork로 명명됨)가 개발되어 정밀하고 수월하게 연약지반의 전단파 속도를 측정할 수 있게 되었다. 이 탄성파시험의 용도를 확장하고자 강성도 측정과 함께 전단강도와 밀도를 추정할 수 있는 상관관계를 시도하였다. 인천의 한 연약지반 현장에서 콘시험과 MudFork를 사용하여 현장탄성파시험을 수행하고, 시료를 채취하여 실내에서 삼축압축시험과 병행하여 공시체의 전단파 속도를 측정하였다. 이 결과로부터 연약지반의 전단강도와 전 단파속도의 상관관계와, 밀도와 전 단파속도의 상관관계를 정립하였다.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.71-79
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• 2023

Air ingress incidents are major safety accidents in very-high-temperature reactors (VHTRs). Air containing a high volume fraction of oxygen may cause severe oxidation of core components at the VHTR, especially for the significantly thin alloy tube wall in the intermediate heat exchanger (IHE). The research objects of this study are Inconel 617 and Incoloy 800H, two candidate alloys for IHE in VHTR. The air ingress accident scenario is simulated with high-temperature air flow at 950 ℃. A continuous oxide scale was formed on the surfaces of both the alloys after the experiment. Because the oxide scale of Inconel 617 has a loose structure, whereas that of Incoloy 800H is denser, Inconel 617 exhibited significantly more severe internal oxidation than Incoloy 800H. Further, Inconel 617 showed a significant decrease in ultimate tensile strength and plasticity after aging for 200 h, whereas Incoloy 800H maintained its tensile properties satisfactorily. Through control experiment under vacuum, we preliminarily concluded that serious internal oxidation is the primary reason for the decline in the tensile properties of Inconel 617.