• 센서학회지
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• 제31권2호
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• pp.102-106
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• 2022

Currently, the demand for real-time monitoring of water quality has increased dramatically. Total organic carbon (TOC) analysis is a suitable method for real-time analysis compared with conventional biochemical oxygen demand (BOD) and chemical oxygen demand (COD) methods in terms of analysis time. However, this method is expensive because of the complicated internal processes involved. The photocatalytic titanium dioxide (TiO2)-based TOC method is simpler as it omits more than three preprocessing steps. This is because it reacts only with organic carbon (OC) without extra processes. We optimized the rate between the TiO2 photocatalyst and binder solution and the TiO2 concentration. The efficiency was investigated under 365 nm UV exposure onto a TiO2 coated substrate. The optimized conditions were sufficient to apply a real-time monitoring system for water quality with a short reaction time (within 10 min). We expect that it can be applied in a wide range of water quality monitoring industries.

• Corrosion Science and Technology
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• 제12권2호
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• pp.102-112
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• 2013

A very high-temperature gas reactor (VHTR) is one of the next generation nuclear reactors owing to its safety, high energy efficiency, and proliferation-resistance. Heat is transferred from the primary helium loop to the secondary helium loop through an intermediate heat exchanger (IHX). Under VHTR environment Alloy 617 is being considered a candidate Ni-based superalloy for the IHX of a VHTR, owing to its good creep resistance, phase stability and corrosion resistance at high temperature. In this study, high-temperature corrosion tests were carried out at 850 - $950^{\circ}C$ in air and impure helium environments. Alloy 617 specimens showed a parabolic oxidation behavior for all temperatures and environments. The activation energy for oxidation was 154 kJ/mol in helium environment, and 261 kJ/mol in an air environment. The scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDS) results revealed that there were a Cr-rich surface oxide layer, Al-rich internal oxides and depletion of grain boundary carbide after corrosion test. The thickness and depths of degraded layers also showed a parabolic relationship with the time. A corrosion rate of $950^{\circ}C$ in impure helium was higher than that in an air environment, caused by difference in the outer oxide morphology.

• 한국기후변화학회지
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• 제4권3호
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• pp.269-278
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• 2013

$SF_6$ 가스는 $CO_2$에 비해 배출량은 적지만 GWP는 $CO_2$ 가스의 22,800배1)로 높으며, 최근 $non-CO_2$에 의한 온실가스 규제가 강화됨으로에 따라 온실가스 감축을 고려한 친환경 $SF_6$ 처리 기술 개발이 대두되고 있다. 본 연구에서는 전력설비 내에서 절연체로 사용되는 $SF_6$ 가스의 배출양상에 따른 배출 특성을 분석하고, 그에 따른 $SF_6$ 가스 저감기술을 살펴보았다. 주요 기술로는 사용 중의 유지보수와 폐기단계에 적용될 수 있는 가스의 회수율($85{\rightarrow}99%$)을 재고시키는 기술과 $SF_6$ 가스 제거를 위한 촉매 제조에 관한 기술 및 차단기 내부 점검 시 별도 $SF_6$ 가스 회수 없이 충전된 상태에서 내시경으로 차단기 내부를 점검하여 $SF_6$ 가스를 저감하는 기술이 있으며, 이러한 기술을 통해 대기 중 $SF_6$ 가스 저감이 이루어질 것으로 판단된다.

• 설비공학논문집
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• 제29권11호
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• pp.570-579
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• 2017

In this study, we examined the multi-stage piston-type air compressors typically used in a railroad vehicle, and the heat transfer efficiency was analyzed according to the design conditions of the heat exchanger (a compressor component module for cooling the compressed high temperature air). For the fin-tube heat exchanger used in the most air compressors, numerical analysis was performed to analyze heat transfer by defining the various rectangle tube sizes and the number of fin-per-unit area as design variables under the same flow rate of compressed air. Also, this analysis compared the temperature of the compressed air. Regarding environmental conditions for analysis, the flow rate of the external cooling air was measured and the mean value of the values was applied. And a "turbulence model" was considered in both the external flow of the cooling air and the internal flow inside the tube. From the results of analysis, it was found that the change of the aspect ratio value of the tube greatly influences the heat transfer efficiency of the compressed air, and influences if the fin density is relatively small. As a result, the optimum design specifications of the heat exchanger for air compressors were confirmed based on the analysis of the heat transfer efficiency, according to the design conditions of fin and tube by the operating temperature range of the compressed air.

• 지질공학
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• 제18권3호
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• pp.277-285
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• 2008

쏘일네일링은 최근 들어 그 적용성이 확대되고 있으나 아직까지 공인된 설계방법이 없다. 또한 쏘일네일링은 설계변수가 많고 설계변수 상호간의 민감도에 대한 연구가 되지 않은 상황에서 명확한 근거 없이 사용되고 있다. 특히, 본 연구의 주요 과제인 네일의 설치각도에 대한 민감성은 다루어지지 않고 있다. 따라서 본 연구는 이론적 계산식을 바탕으로 파괴면에 대한 네일의 각도와 벽체의 높이, 단위중량, 점착력, 내부 마찰각, 네일에 작용하는 인장력 등을 고려하여 안전율을 분석하였다. 그 결과, 배면지반이 수평이고 수직벽체인 경우 네일의 설치 각도는 하향보다 상향이 모두 안전율이 증가하는 것을 확인할 수 있었다.

• Tuberculosis and Respiratory Diseases
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• 제54권2호
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• pp.219-229
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• 2003

배경 및 목적 : 농흉과 합병된 부폐렴성 흉막 삼출의 치료에서 가장 중요한 것은 적절한 항생제 투여와 빠른 배액이다. 흉관 삽관은 소방이 형성되는 경우나 접근이 어려운 경우 성공률이 낮으며, 혈흉, 장기손상, 횡격막 파열, Hornor 증후군 등의 합병증이 보고되는 침습적 술기로, 최근에는 영상 유도에 의한 pigtail 도관 배액술(pigtail catheter drainage, PCD)이 시행되고 있다. 이에 저자 등은 농흉 및 합병된 부폐렴성 흉막 삼출 환자에서 PCD의 유용성을 알아보고자 후향적 연구를 시행하였다. 대상 및 방법 : 1998년 1월부터 1999년 6월까지 가천 의대 길병원에서 농흉 및 합병된 부폐렴성 흉막삼출로 진단되어 PCD시술을 받은 45명을 대상으로, 진단 당시 증상, 음주 및 흡연력, 혈액 검사 소견, 흉수 검사 소견, 방사선 소견(도관 삽관시, 도관 제거시, 도관 제거 한달 후), 삽관 후 24시간 배액량, 삽관 기간, 삽관 후 입원 기간, 외과적 처치여부 등을 조사하여 다음과 같은 결과를 얻었다. 결 과 : 대상환자의 남녀비는 42 : 3, 연령은 중앙값 52세(21~74)이었다. 농흉 환자는 23명, 합병된 부폐렴성 흉막 삼출 환자는 22명이었고, 이 중 PCD만을 시행받았던 4명(3명 : 부폐렴성 흉막삼출, 1명 : 농흉)의 환자가 추적관찰에서 탈락되었다. 이들을 제외한 나머지 환자들 중 36명(80%)에서 PCD 또는 PCD와 유로키나제 사용으로 배액이 가능하였으며, 농흉 환자 23명 중 5명(27.1%)만이 외과적 수술을 시행받았고(흉막 박피술 1명, 개방성 흉강 배액술 3명), 이 중 1명이 사망하였다. PCD만 시행 받은 환자군과 PCD와 유로키나제를 사용한 환자군에서 삽관 기간, 삽관 후 재원 기간 및 24시간 평균 배액량은 유의한 차이가 없었다. PCD만 시행 받은 환자군과 수술적 처치를 받은 군 간에 24시간 평균 배액량의 유의한 차이는 없었으며, 삽관 기간($9.4{\pm}5.25$일 vs. $19.2{\pm}9.42$일, p<0.05), 삽관 후 재원 기간($15.9{\pm}10.45$일 vs. $38.60{\pm}11.5$일, p<0.01)이 수술적 처치를 받은 군에서 더 긴 것으로 나타났다. 또한 PCD와 유로키나제를 사용한 군과 수술적 처치를 받은 군 사이에서도 24시간 평균 배액량의 차이는 없었고 삽관 기간($11.1{\pm}7.35$일 vs. $19.2{\pm}9.42$일, p<0.05)과 삽관 후 재원 기간($17.5{\pm}9.17$일 vs. $38.6{\pm}11.46$일, p<0.01)에 유의한 차이가 있었다. PCD 단독 또는 PCD와 유로키나제를 병행하여 사용한 40명의 환자 중 추적관찰시 탈락된 4명을 제외하고 16명(44.4%)에서 도관 제거시 75% 이상 흉수가 감소하였으며, 17명(47.2%)에서는 50~75%, 1명에서는 25~50% 감소하였고, 2명에서는 25% 미만으로 감소하였다. 도관 제거 한 달 후에는 1명을 제외한 35명(97.2%)이 50% 이상의 호전을 보였다. 추적 관찰 기간 중 pigtail 도관 삽관시 특기할 만한 합병증은 없었다. 결 론 : PCD는 농흉 및 합병된 부폐렴성 흉막 삼출 환자에서 심각한 합병증 없이 효과적으로 조기에 배액할 수 있는 유용한 시술로 사료된다.

• 대한의생명과학회지
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• 제12권1호
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• pp.9-16
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• 2006

We investigated the effects of 835-MHz electromagnetic field (EMF), one of the most popular communication frequency band in Korean code-division multiple-access (CDMA) mobile phone system, on cellular signal transduction. For this, we examined the change of intracellular calcium $([Ca^{2+}]_i)$, reactive oxygen species (ROS) and F-actin polymerization after exposure to 835-MHz EMF followed by the treatment of agonists in Rat-2 fibroblast cells. Culture cells were pretreated with serum-tree medium and concomitantly exposed to 835-MHz at specific absorption rate (SAR) of 4.0 W/kg for 24 hr in a specialized designed apparatus based on Transverse Electro Magnetics (TEM) wave theory. Intracellular $Ca^{2+}$ responses to lysophosphatidic acid (LPA) and epidermal growth factor (EGF) in Rat-2 fibroblast after exposure to 835-MHz EMF were shown to be similar pattern as observed in normal cultured cells. However, the LPA-induced calcium spiking was slightly delayed to 7 sec and sustained thereafter to a little higher ground level under 835-MHz EMF radiation compared to unexposed cells. ROS production level by LPA in the exposed cells was not different from that in control. Furthermore, LPA induced the production of stress fibers with no significant difference in the exposed and unexposed cells. These results suggest that mobile phone radiation (835-MHz, SAR 4.0 W/kg) may not be directly related to signal transduction in Rat-2 fibroblasts except the slight effect of calcium spiking in LPA-induced cells but remain to be further elucidated for possible indirect intervention.

• 한국환경보건학회지
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• 제47권6호
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• pp.540-547
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• 2021

Background: Indoor air pollutants are caused by a number of factors, such as coming in from the outside or being generated by internal activities. Typical indoor air pollutants include nitrogen dioxide and carbon monoxide from household items such as heating appliances and volatile organic compounds from building materials. In addition there is carbon dioxide from human breathing and bacteria from speaking, coughing, and sneezing. Objectives: According to recent research results, most indoor air pollution is known to be greatly affected by internal factors such as burning (biomass for cooking) and various pollutants. These pollutants can have a fatal effect on the human body due to a lack of ventilation facilities. Methods: We fabricated a polydopamine (PDA) layer with Ti substrates as a coating on supported glass fiber fabric to enhance its photo-activity. The PDA layer with TiO₂ was covalently attached to glass fiber fabric using the drop-casting method. The roughness and functional groups of the surface of the Ti substrate/PDA coated glass fiber fabric were verified through infrared imaging microscopy and field emission scanning electron microscopy (FE-SEM). The obtained hybrid Ti substrate/PDA coated glass fiber fabric was investigated for photocatalytic activity by the removal of ammonia and an epidermal Staphylococcus aureus reduction test with lamp (250 nm, 405 nm wavelength) at 24℃. Results: Antibacterial properties were found to reduce epidermal staphylococcus aureus in the Ti substrate/PDA coated glass fiber fabric under 405 nm after three hours. In addition, the Ti substrate/PDA coated glass fiber fabric of VOC reduction rate for ammonia was 50% under 405 nm after 30 min. Conclusions: An electron-hole pair due to photoexcitation is generated in the PDA layer and transferred to the conduction band of TiO₂. This generates a superoxide radical that degrades ammonia and removes epidermal Staphylococcus aureus.

• 한국산림과학회지
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• 제101권3호
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• pp.426-433
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• 2012

본 연구는 곰취 임간재배 개선방안을 모색하고 필요한 정책수립 및 컨설팅을 위한 기초자료 마련을 위해 수행되었다. 이를 위해 인제군 산림복합경영자 중 곰취를 재배하는 8개 임가를 대상으로 심층면접 설문을 실시하여 조성단계에서 수확작업에 이르는 각 단계별 노동투입량 등 총비용과 조수입, 순수익을 계산하여 경영실태를 분석하였다. 수익성은 수익비용비율, 순현재가치법, 내부수익률법을 이용하여 분석하였다. 분석결과 할인율 3%를 적용할 경우 IRR 48.6%, B/C ratio 1.5, NPV 41,419천원/ha으로 수익성이 높은 것으로 나타났다. 사례 임가별로 IRR 147.9%~3.5%의 심한 편차를 보였는데, 이는 곰취 임간재배가 현재 초기단계로 아직 표준재배법이 정립되지 않아 재배자마다 재배기술의 차이가 있기 때문인 것으로 사료된다. 재배의 각 단계별로 보다 체계적인 작업법을 정립하고, 이에 필요한 정책적 지원이 따른다면 곰취 임간재배는 국내 임가의 소득창출은 물론이고 안전한 먹거리 공급과 도 시민의 휴양 체험지 제공에도 큰 역할을 할 것으로 기대된다.

• 대한한의학회지
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• 제44권1호
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• pp.65-75
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• 2023

Objectives: Objectives: In this study, we define a medical service type that combines Western medicine, Korean medicine, and complementary and alternative medicine (CAM) as an integrated medical service. This study, as part of tertiary hospital-based integrated medical service model and clinical field application, aims to collect status and opinions on integrated medical service for medical staff in the field. Methods: This is a survey study, and was conducted on doctors from Kyung Hee University Hospital and Korean medicine doctors from Kyung Hee University Korean Medicine Hospital. Respondents were recruited on a first-come, first-served basis until the number of respondents reached 120. The investigation was conducted for a total of 16 days from October 4, 2021 to October 19, 2021 by e-mail. Results: Recognition of integrated medical services was confirmed to be 45.8%, and 49.2% responded positively to the necessity of it. As a group of diseases that require the establishment of integrated medical services in the future, 'disorders of musculoskeletal systems and connective tissues' was the highest. The most expected advantages of providing integrated medical services were 'increased satisfaction of patients and guardians' and 'increased treatment effects.' Conclusions: In this study, we investigated the perception of doctors and Korean medicine doctors on integrated medical services that combine Western medicine, Korean medicine, and CAM. It has been confirmed that medical staff generally have a positive perception of integrated medical services, and if the scientific basis for the effect of integrated medical services is supported, the rate of positive perception is expected to increase.