• 한국산학기술학회논문지
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• 제16권10호
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• pp.6445-6452
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• 2015

건물용 공기조화기의 냉수 코일은 작동조건에 따라 건표면, 습표면 또는 부분적인 습표면이 형성된다. 따라서 냉수코일을 적절히 설계하기 위해서는 건표면과 습표면, 그리고 부분적 습표면에 대한 열전달 해석이 필요하다. 본 연구에서는 미소체적에 대한 해석을 통하여 냉수코일의 성능을 계산하는 미소체적 모델을 제시하였다. 해석 모델의 예측치를 냉수코일 실험결과와 비교한 결과 미소 체적 모델은 공기측 전열량을 10.1% 이내에서 예측하고 공기측 압력손실을 11.1%, 현열비도 5.7%내로 예측하였다. 해석 모델을 활용하여 물측 회로의 변화가 냉수코일의 성능에 미치는 영향을 검토하였다.

• International Journal of Industrial Entomology and Biomaterials
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• 제45권2호
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• pp.70-77
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• 2022

Wet-spun regenerated silk fibroin (RSF) fibers have been extensively studied owing to their 1) useful properties as biomaterials, including good blood compatibility and cyto-compatibility; 2) the various methods available to control the structural characteristics and morphology of the fiber, and 3) the possibility of fabricating blended fibers and new material-embedded fibers. In this study, silk nanofibrils prepared using a new method were embedded in RSF to fabricate wet-spun silk nanofibril/RSF composite fibers. Up to 2% addition of silk nanofibril, the silk nanofibril/RSF dope solution showed slight shear thinning, and the G' and G" of the dope solution were similar. However, above 3% silk nanofibril content, the viscosity of the dope solution significantly increased. In addition, shear thinning was remarkably evident, and the G' of the dope solution was much higher than the G", indicating a very elastic state. As the silk nanofibril content was increased, the wet-spun silk nanofibril/RSF composite fiber became uneven, with a rough surface, and more beaded fibers were produced. Scanning electron microscopy observations revealed that the beaded fibers were attributed to the inhomogeneous dispersion and presence of agglomerates of the silk nanofibrils. As the silk nanofibril content and RSF concentration increased, the maximum draw ratio decreased, indicating the deterioration of the wet spinnability and post-drawing performance of silk nanofibril/RSF.

• 한국수자원학회논문집
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• 제42권5호
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• pp.415-424
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• 2009

대수층 바닥이 해수면보다 낮은 해안 지역에서는 관정에서의 적정양수량이 해수침투 여부에 의하여 결정될 수 있다. 이러한 지역에서 관정의 적정 양수량을 초과하는 수요를 만족시키기 위하여 과잉양수를 시행해야하면 우기의 잉여 지표수를 대수층에 주입함으로서 과잉 양수정을 연중 보호할 수 있다. 본 연구에서는 최소의 주입으로 과잉 양수정을 보호할 수 있는 주입정의 위치와 우기의 주입량을 계산하는 전산모델을 개발하였다. 경계면모델과 최적화방법을 조합하여 개발된 수치모델에서 목적함수는 주입량의 최소화이며 제약조건으로 해수침투와 지하수 고갈을 고려하였다. 상태변수는 과잉양수량, 설계연한, 우기 기간, 그리고 양수정에서의 해수비율이다. 지하수 개발이 어려운 수리지질 특성을 가진 소규모 가상 도서에 대하여 본 기술의 적용성과 지하수 추가 개발의 가능성을 평가하였다. 적용결과 다양한 조건에서도 적정개발량을 초과하는 지하수 관정을 보호할 수 있는 주입정의 가동이 가능한 것으로 나타났다.

• 한국결정성장학회지
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• 제32권1호
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• pp.40-44
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• 2022

35 % 농도의 염산 용액을 이용하여 α-Ga₂O₃ epitaxy 박막의 습식 식각을 수행하였다. 35 % 염산 용액의 온도가 증가함에 따라 α-Ga₂O₃ epitaxy 박막의 식각 속도가 증가하였고, 본 연구에서 시도한 가장 높은 온도인 75℃에서 119.6 nm/min의 식각 속도를 나타내었다. 식각 반응의 활성화 에너지는 0.776 eV로 계산되었고, HCl 용액에서의 습식 식각은 reaction-limited 반응 기구에 의해 지배됨을 확인하였다. 각 온도에서 식각된 표면들의 AFM 분석결과 식각 용액의 온도가 증가함에 따라 식각된 표면의 표면조도가 증가함을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.235-236
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• 2008

Wet etched ZnO:Al films for thin film solar cells were prepared by Facing Target sputtering(FTS) method. Wet etching has been used to produce a rough TCO surface that enables light trapping in the absorber. The ZnO:Al films for thin film solar cells were etched by HCl 0.5%. The etching performance of ZnO:Al films can be tuned by changing etching time. The etched ZnO:Al films compared to a smooth ZnO:Al thin film structure. From the results, the lowest resistivity of deposited films was $5.67\times10^{-4}$ [$\Omega$-cm] and the transmittance of all ZnO:Al thin films were over 80% in visible range.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.237-240
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• 2001

In this paper, we have presented processing technique about wet etching for silicon membrane construction formation. In order to make selective etching of backside silicon wafer, we used Si$_3$N$_4$ layer by PECVD(Plasma Enhanced Chemical Vapor Deposition). We have measured the surface thickness in backside silicon wafer after anisortropic wet etching with KOH:distilled water solutions. Through this experiment, we acquired the etching rate for 1.29${\mu}{\textrm}{m}$/min. The average rough of Si-membrane frontside and backside was 0.26${\mu}{\textrm}{m}$, 0.90${\mu}{\textrm}{m}$, respectively.

• Journal of Welding and Joining
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• 제2권2호
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• pp.62-69
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• 1984

In this study, cold crack susceptibility of high strength steel (ABS EH32 Steel) welded zone with shielded metal are welding was investigated by tensile restraint cracking test method. Effects of diffusible hydrogen content on root cracking, lower critical stress, crack initiation and fracture mode, hardness value distribution of welded zone and fractograph were mainly investigated. Following conclusions are made: 1. In the view of the lower critical stress level, wet electrode, containing much diffusible hydrogen content shows lower value than dried electrode. 2. Hardness value(Hv 5kg) in Heat Affected Zone of wet electrode is higher than that of dried electrode caused by hydrogen embrittlement. 3. In the case of wet electrode, root crack is initiated and propagated in Heat Affected Zone and then propagated to weld metal, but using of dried electrode, root crack is initiated in Heat Affected Zone and propagated to weld metal without propagating in HAZ. 4. For wet electrode, quasi-cleavage fracture mode is majorly observed on the fracture surface of HAZ and partially of weld metal due to hydrogen embrittlement.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.387.2-387.2
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• 2016

Glass texturing is a sufficient method for changing the surface morphology to enhance the light trapping. In this study, glass texturing was applied to the perovskite solar cell for improving the current density. Glass substrates (back-side glass of FTO coated glass substrate) were textured by randomly structure assisted wet etching process using diluted HF solution at a constant concentration of etchants (HF:H2O=1:1). Then, the light trapping properties of suitable films were controlled over a wide range by varying the etching time (1, 2, 3, 4 and 5 min.). The surface texturing changed the reflected light in an angle that it can be reflected by substrate glass surface. As a result, Current density and cell efficiency were affected by light trapping layer using glass texturing method in perovskite solar cells.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.984-993
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• 1993

land application of sewage sludge requires careful monitoring because of its potential for contamination of surface water and groundwater. A rainfall simulator was used to investigated the effects of freshly applied sludge on runoff of sediment and nutrients from agricultural crop lands. Rain was applied to 16 experimental field plots. A three run sequence was used to simulate different initial moisture conditions. Runoff, sediment and nutrient losses were monitored at the base of each plot during the simulated rainfall events. Sludge was surface applied and incorporated at conventionally -tilled plots and surface applied at no-till plots, at rates of 0, 75, 150 kg-N/ha. No-till practices greatly reduced runoff, sediment , and nutrient losses form the sludge treated plots, relative to the conventional tillage practices. Incorporation of the sludge was effective in reducing nutrient yields at the conventionally-tilled plots. This effect was more pronounced during the third rain torm, with wet initial conditions. Peak loadings of nutrients appeared during the rainstorm with wet initial conditions.

• 음성과학
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• 제13권1호
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• pp.85-94
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• 2006

The aim of this study was to examine the characteristics in duration and amplitude of the submental muscle activities during dry and wet swallowing. We examined the middle suprahyoid muscle activities in 32 normal adult women during three swallowing conditions, that is, dry as well as 5 mL & 10 mL water swallowings, using a surface EMG. From the results, there were significant differences in duration: the longest in dry swallowing and shortest in 5 mL water swallowing. However, the mean amplitude per msec increased as the duration decreased. This may imply motor equivalence in swallowing stating that duration and amplitude are complementary in order to achieve a given swallowing goal.