• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.359-362
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• 2012

We have employed Kelvin force microscopy (KFM) system to measure the potential change of a single SnO2 nanowire which had been synthesized on the Au thin film by a thermal process. By using the KFM probing technique, Rh coated conducting cantilever can approach a single SnO2 nanowire in nano scale and get the potential images with oscillating AC bias between Au electrode and cantilever. Also, during imaging the potential status, we controlled the concentration of oxygen in measuring chamber to change the ionosorption rate. From the results of such experiments, we verified that the surface potential as well as doping type of a single SnO2 nanowire could be changed by oxygen ionosorption.

• Journal of Chest Surgery
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• 제24권3호
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• pp.310-321
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• 1991

Between April 1986 and September 1990, 34 patients with a single or dominant right ventricle underwent modified Fontan procedure for definite palliation in Seoul National University Children`s Hospital. Their age at operation ranged from 8 months to 14 years [Mean 5.5 years]. The ventricular chamber was solitary and of indeterminate trabecular pattern in 6 patients. 28 patients had posteriorly located rudimentary chamber, all of which were trabecular pouches having no communication with outlet septum. The patterns of atrioventricular connection were common inlet[9], double inlet [11], left atrioventricular valve atresia [12] and right atrioventricular valve atresia with L-loop [2]. Pulmonary outflow tracts were atretic in 7 patients and stenotic in 26 patients. Major associated anomalies included anomalous systemic venous drainage [15], dextrocardia [12] and total anomalous pulmonary venous connection[3]. Shunt operations were previously performed in 13 patients and pulmonary artery banding and atrial septectomy in 1 patients. Surgery included intraatrial baffling in 26 patients, bidirectional cavopulmonary shunt in 13 patients, atrioventricular valve obliteration in 3 patients and atrioventricular valve replacement in 3 patients. Central venous pressure measured postoperatively at intensive care unit ranged from 18cm H2O to 28cm H2O [mean 23.2cm H2O]. Hospital mortality was 35.3% [12/34], all died out of low output syndrome. Suspected causes of low output syndrome include ventricular dysfunction [8], hypoplastic or tortuous pulmonary artery [2] and elevated pulmonary vascular resistance [2]. 19 patients had 31 major complications including low output syndrome [18], arrhythmia [4], acute renal failure [3] and respiratory failure [3]. Mortality rate was significantly higher in the groups receiving intraatrial baffling and AV valve replacement respectively [p<0.05]. 20 patients were followed up postoperatively with the mean follow-up period 15.0$\pm$11.6 months. There were no late death and follow-up catheterization was performed in 10 patients. Mean right atrial pressure was 15.4$\pm$6.8mmHg and ventricular contraction was reasonable in all but one case. Thus, Fontan principle can be applied successfully to all the patients with complex cardiac anomaly of single ventricle variety and better results can be anticipated with judicious selection of patient and improvement of postoperative care.

• 한국태양에너지학회 논문집
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• 제27권2호
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• pp.111-119
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• 2007

The annual mean temperature of South Korea has risen by $1.3^{\circ}C$ for last 100 years by urbanization and industrialization. Especially, the frequency of unusual hot weather in summer increases for a long time and the frequency of unusual cold weather in winter clearly decreases. In recently, The considerable portion of curtain wall system is appled to building skin in domestic. As related to this, the Korea Institute of Construction Technology devised the box typed double skin facade(It is occasionally called as FDFS : Functional Double Facade System) as an alternative that reflects the distinctive local climate and saves cooling energy. Two mock-ups($49m^*4.9m$) applied to single skin(curtain wall) and double skin each were monitored under the outdoor condition. Therefore, the characteristics of natural ventilation and cooling energy consumption of each window had been analyzed in real time. The results of this study are summarized as follow, Analysis of the experiment on an air conditioner: the indoor temperature of the chamber with FDFS is lower than that of the chamber with single skin facades by $3{\sim}6$ degrees(C). A temperature variation of about $1{\sim}2$ degrees between the 0.2m and 1.7m height of the mock-up occurs in FDFS, while that of about maximum 7 degrees occurs in single skin facade at noon with abundant intensity of solar accident. Also, 67 percent of energy consumption for air conditioning has been saved.

• 신재생에너지
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• 제19권4호
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• pp.20-26
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• 2023

Emitted CO₂ is an attractive material for microbial electrochemical CO₂ reduction. Microbial electrochemical CO₂ reduction (i.e., microbial electrosynthesis, MES) using biocatalysts has advantages compared to conventional CO₂ reduction using electrocatalysts. However, MES has several challenges, including electrode performance, biocatalysts, and reactor optimization. In this study, an MES system was investigated for optimizing reactor types, counter electrode materials, and CO₂-converting microorganisms to achieve effective CO₂ upcycling. In autotrophic cultivation (supplementation of CO₂ and H₂), CO₂ consumption of Rhodobacter sphaeroides was observed to be four times higher than that with heterotrophic cultivation (supplementation of succinic acid). The bacterial growth in an MES reactor with a single-chambered shape was two times higher than that with a double chamber (H-type MES reactor). Moreover, a single-chambered MES reactor equipped with titanium mesh as the counter electrode (anode) showed markedly increased current density in the graphite felt as a working electrode (cathode) compared to that with a graphite felt counter electrode (anode). These results demonstrate that the optimized conditions of a single chamber and titanium mesh for the counter electrode have a positive effect on microbial electrochemical CO₂ reduction.

• 한국농림기상학회지
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• 제22권2호
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• pp.79-91
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• 2020

온실가스 배출량의 정확한 평가는 모든 기후변화 대응 연구의 초석이며, 신뢰성이 높은 온실가스 배출량의 평가는 모든 기후변화 예측 및 모델링 연구의 실질적인 기초자료로서 활용된다. 온실가스 배출량 산정 기반 기술로서 온실가스 배출량 현장 모니터링 기술, 배출계수의 불확도 평가 기술, 온실가스 배출량 및 저감량 검증 기술 등이 필수적이다. 이런 기반 기술의 핵심에는 토양-식생-대기 간에 교환되는 온실가스 플럭스 산정을 위해 가장 보편적으로 많이 사용되는 폐쇄형 정적 챔버법의 모니터링 기술이 자리 잡고 있다. 본 연구에서는 농업분야 온실가스 단일 배출원으로 가장 큰 부분을 차지하는 벼논에서 발생하는 CH₄ 플럭스 측정용 폐쇄형 챔버법의 기술적 근간과, 수동형 챔버법에서 전 과정의 자동화 시스템으로 발전을 거듭하고 있는 자동화 챔버 모니터링 기술개발에 대한 국내·외 동향을 소개하였다. 이를 바탕으로 보편적으로 사용하고 있는 챔버법의 표준화된 방법의 고찰과 정확한 현장 자료를 얻기 위한 품질관리 방안이 마련될 수 있을 것이다. 또한 CH₄ 플럭스 측정방법의 신뢰성 높은 기술 발전 방향에 대해 조망하여 벼논 CH₄ 배출량 산정 결과들의 신뢰성 향상에 기여하게 될 것으로 전망한다.

• 대한한의학원전학회지
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• 제26권4호
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• pp.267-280
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• 2013

Objective : One of the unique syndromes in Asian traditional medicine named 'heat entering the blood chamber(熱入血室, HEBC)' first appeared in Shanghanlun(傷寒論) and Jinguiyaolue(金匱要略) written by Zhangzhongjing(張仲景) who is the most famous doctor in ancient China. Method : Through comparison between Huangdineijing(黃帝內經), Shanghanlun(傷寒論), Jinguiyaolue(金匱要略) and other medical texts, the correct meaning, causes and mechanisms of HEBC can be analysed and organized to suggest new view of HEBC in modern society. Result : This syndrome is usually occurred in women during catching cold and menstruation, accompanying alternation of chillness and fever, pseudo-malaria, delirium, raveled chest(結胸), uterine hemorrhage, etc. The main sign of this syndrome, delirium belongs to the category of liver disease and fever in Huangdineijing(黃帝內經) which is a document more early published than Shanghanlun. Although there are still many other comprehensions about what blood chamber is, it could be the same as uterus according to Huangdineijing, it is relevant to the control of menstruation and emotions, and the function of liver and thoroughfare vessel(衝脈). Conclusion : HEBC is a syndrome exclusive to women, caused by their unique physical and psychological characteristics. It's beginning can be found in Huangdineijing, and by Shanghanlun and Jinguiyaolue, its concept as a single disease pattern becomes established. In other words, HEBC is a complex disease related to menstruation and its related hormonal dysfunctions, closely related to PMS, menopausal syndrome of today. Physical symptoms accompanied by psychological anxiety and fear is characteristic of this condition. Therefore gynecological approaches as well as socio-cultural issues related to women in modern society must be adopted when dealing with HEBC.

• 동력기계공학회지
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• 제12권4호
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• pp.5-11
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• 2008

The RI gasoline engine haying a sub-chamber had a high cycle variation due to the difficulty of the residual gas scavenge in the sub-chamber. To solve this problem and improve the combustion performance of RI engine, we devised a method to inject directly CNG fuel into the sub-chamber. A DI diesel engine of single cylinder was converted into a RI-CNG engine and an electronic control unit for the engine was manufactured. In this study, the combustion characteristics of the RI-CNG engine were investigated with the injection timings and air excess ratios at the load conditions of 50% throttle open rate and 1700rpm. As the results from this study, the RI-CNG engine worked reliably under the condition of the ignitable lean limit of $\lambda=1.7$ by showing the $COV_{imep}$ below about 5%. And the highest thermal efficiency could be obtained in the injection timing that produced the high imep and the low $COV_{imep}$ at the same time. The CO emission concentration indicated very low values and the THC and $NO_x$ showed an opposite pattern. With a view to improving the thermal efficiency and reducing the harmful emissions, the proper control region of the ignition timing and the mixture ratio were nearly ATDC $20^{\circ}\sim50^{\circ}$ and $\lambda=1.4$ respectively.

• Asian Journal of Atmospheric Environment
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• 제8권4호
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• pp.175-183
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• 2014

To visually and chemically verify the rainout of soot particles, a model experiment was carried out with the cylindrical chamber (0.2 m (D) and 4 m (H)) installing a cloud drop generator, a hydrotherometer, a particle counter, a drop collector, a diffusing drier, and an artificial soot particle distributer. The processes of the model experiment were as follows; generating artificial cloud droplets (major drop size : $12-14{\mu}m$) until supersaturation reach at 0.52%-nebulizing of soot particles (JIS Z 8901) with an average size of $0.5{\mu}m$-counting cloud condensation nuclei (CCN) particles and droplets by OPC and the fixation method (Ma et al., 2011; Carter and Hasegawa, 1975), respectively - collecting of individual cloud drops - observation of individual cloud drops by SEM - chemical identifying of residual particle in each individual droplet by SEM-EDX. After 10 minutes of the completion of soot particle inject, the number concentrations of PM of all sizes (> $0.3{\mu}m$) dramatically decreased. The time required to return to the initial conditions, i.e., the time needed to CCN activation for the fed soot particles was about 40 minutes for the PM sized from $0.3-2.0{\mu}m$. The EDX spectra of residual particles left at the center of individual droplet after evaporation suggest that the soot particles seeded into our experimental chamber obviously acted as CCN. The coexistence of soot and mineral particle in single droplet was probably due to the coalescence of droplets (i.e., two droplets embodying different particles (in here, soot and background mineral particles) were coalesced) or the particle capture by a droplet in our CCN chamber.

• 한국추진공학회지
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• 제17권2호
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• pp.122-127
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• 2013

고성능 폐회로 액체로켓엔진 시스템에 적용되는 산화제 과잉 예연소기 내에서 발생하는 연소 압력 섭동 데이터에 대한 분석 결과를 수록하였다. 연소실험은 두 단계의 압력 값을 순차적으로 형성하였는데 상대적으로 저압 조건에서만 78 Hz의 특성 주파수를 갖는 자발적인 압력 섭동이 발생하였다. 이와 같은 연소 불안정은 bulk mode에 해당하는 것으로 판단된다. 압력 섭동의 세기는 rms 기준으로 연소실 정압 대비 13.3%에 해당하며, 설계압 구간(19.3 MPa)에서는 매우 안정적인 모습을 보였다. 이와 같은 bulk mode는 연소실 내부에서 특성 압력파의 위상차가 없이 전체 공간에서 압력이 증가와 감소를 반복하는 것으로 Helmholtz 공진기와 비슷한 특성을 보이는 것으로 판단된다.

• 한국터널지하공간학회 논문집
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• 제23권4호
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• pp.233-252
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• 2021

본논문은 쉴드 TBM 챔버(Chamber) 내 배토처리 효율성 향상을 위한 연구이다. 현재 국내에서는 TBM 공법을 이용한 시공사례가 증가하는 추세이다. TBM 공법 사용의 증가에 따른 디스크 커터(Disc Cutter), 커터 비트(Cutter bit) 및 세그먼트와 같은 TBM 공법의 연구 또한 증가하는 추세를 보인다. 하지만 챔버와 챔버 내 교반 성능에 대한 연구는 미비한 실정이다. 원활한 배토처리와 굴착토의 거동을 개선하기 위하여 챔버 내 효과적인 믹싱 바 배치에 따른 교반 효율 변화에 대한 연구를 수행하였다. 축소모형 실험은 식별의 용이성을 위하여 색이 다른 플라스틱 소재를 사용하여 지반을 조성하였다. 또한 믹싱 바 배치를 상이하게 하여 4가지 Case로 분류하였으며, 입도분포를 단입도와 다입도로 분류하여 총 8가지의 Case로 실험을 진행하였다. 모든 Case의 커터헤드의 회전속도는 5 RPM으로 동일하며, 실험시간 또한 동일한 조건인 1분 30초로 진행하였다. 교반 효율을 확인하기 위하여 각 Case별 상부, 중부(좌 or 우), 하부 위치의 시료를 채취하여 분석하였다. 축소모형실험 결과 실제 사용되는 Case 1과 Case 1-1보다 새로운 배치방법인 Case 4와 Case 4-1의 교반 효율이 증가하는 양상을 보인다. 그에 따라 챔버 내 믹싱 바 배치를 변경하여 교반 효율을 증가시킬 수 있을 것으로 보이며, 교반 효율증가에 따라 공기 절약에 효과적일 것으로 판단된다. 따라서 본 연구는 국내 쉴드 TBM 공법 활용에 있어 큰 지표로써 작용할 것으로 보인다.