• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.473-480
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• 2014

Upon setting up a dedicated plastic greenhouse for tomato cultivation developed by the Rural Development Administration on the Gyehwa reclaimed land, this study was aimed at analyzing the problems can be occurred in the installation of plastic greenhouse on reclaimed lands as well as finding out solutions for improvement. A relatively cheaper wooden pile was used in the installation in order to supplement the soft ground conditions. Based on the results of ground investigation of the installation site, both the allowable bearing capacity and pulling resistance of the wooden pile with a diameter of 150 mm and a length of 10 m were computed and came out to be 30.645 kN. It was determined that the values were enough to withstand the maximum compressive force (17.206 kN) and the pullout force (20.435 kN) that are generally applied to the greenhouse footing. There are three problems aroused in the process of greenhouse installation, and the corresponding countermeasures are as follow. First, due to the slightly bent shape of the wooden pile, there were phenomenon such as deviation, torsion, and fracture when driving the pile. This could be prevented by the use of the backhoe (0.2) rotating tongs, which are holding the pile, to drive the pile while pushing to the direction of the driving and fixing it until 5 m below ground and applying a soft vibrating pressure until the first 2 m. Second, there exists a concrete independent footing between the column of the greenhouse and the wooden pile driven to the underground water level. Since it is difficult to accurately drive the pile on this independent footing, the problem of footing baseplate used to fix the column being off the independent footing was occurred. In order to handle with this matter, the diameter of the independent footing was changed from 200 mm to 300 mm. Last, after films were covered in the condition that the reinforcing frame and bracing are not installed, there was a phenomenon of columns being pushed away by the strong wind to the maximum of $11m{\cdot}s^{-1}$. It is encouraged to avoid constructions in winter, and the film covering jobs always to be done after the frame construction is completely over. The height of the independent footing was measured for 9 months after the completion of the greenhouse installation, and it was found to be within the margin of error meaning that there was no subsidence. The extent to the framework distortion and the value of inclinometers as well showed not much alteration. In other words, the wooden pile was designed to have a sufficient bearing capacity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4441-4449
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• 2015

The purpose of this study is to find out how children's musical is done in the early childhood education field. To find out the realities of children's musical watching, seek problems and way to improve, educationally new alternative, we selected subjects of study as follows. First, how children's musical of the early childhood education center is done? Second, how the education related children's musical of the early childhood education center is done? Third, what is the problem and way to improve of watching children's musical? To find out these, the result of the teachers(159 people) who are working the kidergarten and the early childhood education center is as follows. First, Children were very interested in watching musical and could get new, various experience and culture. Second, when watching musical, kindergarten and the early education center did pre-exploration everytime except same place. second, Of post-education activity, drawing activity related with musical content, story-making activity, developing to child's act are educationally effective. Third, whey watching musical, there is much pressure about danger and safety. So it is hard to control when children is moving. This significant result shows the importance of educational effects of the musical watching and the proposed expansion of the opportunity to experience a musical watching of the various educational approaches.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.214.1-214.1
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• 2015

Thin-film transistors (TFTs)의 채널층으로 널리 쓰이는 indium-gallium-zinc oxide (IGZO)는 높은 전자 이동도(약 10 cm2/Vs)를 나타내며 유기 발광 다이오드디스플레이(OLED)와 대면적 액정 디스플레이(LCD)에 필수적으로 사용되고 있다. 하지만, 이러한 재료는 우수한 TFT의 채널층의 특성을 가지는 반면, ZnO 기반 재료이기 때문에 소자 구동에서의 안정성은 가장 큰 문제로 남아있다. 따라서 최근, IGZO layer의 특성을 향상시키기 위한 연구가 다양한 방법으로 시도되고 있다. IGZO의 조성비를 조절하여 전기적 특성을 최적화거나 IGZO layer의 조성 중 Ga을 다른 금속 메탈로 대체하는 연구도 이루어지고 있다. 그러나 IGZO에 미량의 도펀트를 첨가하여 박막 특성 변화를 관찰한 연구는 거의 진행되지 않고 있다. 산화물 TFTs의 전기적 특성과 안정성은 산소 함량에 영향을 많이 받는 것으로 알려져 있으며, 더욱이 TFT 채널층으로 쓰이는 IGZO 박막의 고유한 산소 공공은 디바이스 작동 중 열적으로 활성화 되어 이온화 상태가 될 때 소자의 안정성을 저하시키는 것이 문제점으로 지적되고 있다. 그러므로 본 연구에서는 낮은 전기 음성도(1.22)와 표준전극전위(-2.372 V)를 가지며 산소와의 높은 본드 엔탈피 값(719.6 kJ/mol)을 가짐으로써 산소 공공생성을 억제할 것으로 기대되는 yttrium을 IGZO의 도펀트로 도입하였다. 따라서 본 연구에서는 Y-IGZO의 박막 특성 변화를 관찰하고자 한다. 본 연구에서는 magnetron co-sputtering법으로 IGZO 타깃(DC)과 Y2O3 타깃(RF)를 이용하여 기판 가열 없이 동시 방전을 이용해 non-alkali glass 기판 위에 증착 하였다. IGZO 타깃은 DC power 110 W으로 고정하였으며 Y2O3 타깃에는 RF Power를 50 W에서 110 W까지 증가시키면서 Y 도핑량을 조절하였다. Working pressure는 고 순도 Ar을 20 sccm 주입하여 0.7 Pa로 고정하였다. 모든 실험은 $50{\times}50mm$ 기판 위에 총 두께 $50nm{\pm}2$ 박막을 증착 하였으며, 그 함량에 따른 전기적 특성 및 광학적 특성을 살펴보았다. 또한, IGZO 박막 제조 시 박막의 안정화를 위해 열처리과정은 필수적이다. 하지만 본 연구에서는 열처리를 진행하지 않고 Y-IGZO의 안정성 개선 여부를 보기 위하여 20일 동안 상온에서 방치하여 그 전기적 특성변화를 관찰하였다. 나아가 Y-IGZO 채널 층을 갖는 TFT 소자를 제조하여 소자 구동 특성을 관찰 하였다. Y2O3 타깃에 가해지는 RF Power가 70 W 일 때 Y-IGZO박막은 IGZO박막과 비교하여 상대적으로 캐리어 밀도는 낮은 반면 이동도는 높은 최적 특성을 얻을 수 있었다. 상온방치 결과 Y-IGZO박막은 IGZO박막에 비해 전기적 특성 변화 폭이 적었으며 이것은 Y 도펀트에 의한 안정성 개선의 결과로 예상된다. 투과도는 Y 도핑에 의하여 약 1.6 % 정도 상승하였으며 밴드 갭 내에서 결함 준위로 작용하는 산소공공의 억제로 인한 결과로 판단된다.

• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.172-175
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• 2001

Nanophase catalyst layer for direct methanol fuel cell has been fabricated by magnetron sputtering method. Catalyst metal targets and carbon were sputtered simultaneously on the Nafion membrane surface at abnormally higher gas (Ar/He mixture) pressure than that of normal thin film processing. They could be coated as a novel structure of catalyst layer containing porous PtRu or Pt and carbon particles both in nanometer range. Membrane electrode assembly made with this layer led to a reduction of the catalyst loading. At the catalyst loading of 1.5mg $PtRu/cm^2$ for anode and 1mg $Pt/cm^2$ for cathode, it could provide $45 mW/cm^2$ in the operation at 2 M methanol, 1 Bar Air at 80"C. It is more than $30\%$ increase of the power density performance at the same level of catalyst loading by conventional method. This was realized due to the ultra fine particle sizes and a large fraction of the atoms lie on the grain boundaries of nanophase catalyst layer and they played an important role of fast catalyst reaction kinetics and more efficient fuel path. Commercialization of direct methanol fuel cell for portable electronic devices is anticipated by the further development of such design.

• The Journal of Korean Academy of Prosthodontics
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• v.17 no.1
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• pp.23-34
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• 1979

In this study, the adhesive strength of three commercial polycarboxylate cements to ten types of dental casting alloys, such as gold, palladium, silver, indium, copper, nickel, chromium, and human enamel and dentine were measured and compared with that of a conventional zinc phosphate cement. The $8.0mm{\times}3.0mm$ cylindrical alloy specimens were made by casting. The enamel specimens were prepared from the labial surface of human upper incisor, and the dentine specimens were prepared from the occulusal surface of the human molar respectively. Sound extracted human teeth, which had been kept in a fresh condition since, extraction, were mounted in a wax box with a cold-curing acrylic resin to expose the flattened area. The mounted teeth were then placed in a Specimen Cutter (Technicut) and were cut down under a water spray, and then the flat area on the all specimens were ground by hand with 400 and 600 grit wet silicone carbide paper. Two such specimens were then cemented together face-to-face with freshly mixed cement, and moderate finger pressure was applied to squeeze the cement to a thin and uniform film. All cemented specimens were then kept in a thermostatic humidor cabinet regulated at $23{\pm}2^{\circ}C.$ and more than 95 per cent relative humidity and tested after 24 hours and 1 week. Link chain was attached to each alloy specimen to reduce the rigidity of the jig assembly, and then all the specimens were mounted in the grips of the Instron Universal Testing Machine, and a tensile load was delivered to the adhering surface at a cross head speed of 0.20 mm/min. The loads to which the specimens were subjected were recorded on a chart moving at 0.50 mm/min. The adhesive strength was determined by measuring the load when the specimen separated from the cement block and by dividing the load by the area. The test was performed in a room at $23{\pm}2^{\circ}C.$ and $50{\pm}10$ per cent relative humidity. A minimum of five specimens were tested each material and those which deviated more than 15 per cent from the mean were discarded and new specimens prepared. From the experiments, the following results were obtained. 1) It was found that the adhesive strength of the polycarboxylate cement to all alloys tested was considerably greater than that of the zinc phosphate cement. 2) The adhesive strength of the polycarboxylate cements was superior to the non precious alloys, such as the copper, indium, nickel and chromium alloys, but it was inferior to the precious gold, silver and palladium alloys. 3) Surface treatment of the alloy was found to be an important factor in achieving adhesion. It appears that a polycarboxylate cement will adhere better to a smooth surface than to a rough one. This contrasts with zinc phosphate cements, where a rough helps mechanical interlocking. 4) The adhesion of the polycarboxylate cement with enamel was found superior to its adhesion with dentine.

• Fire Science and Engineering
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• v.16 no.1
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• pp.1-7
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• 2002

Halogen-based fire suppressing agents have environmental problems because they cause the stratospheric ozone depletion and globe warming. Hence, fire suppression system using fine water mist became the center of interest as a substitution of halon. As a study about this, it is in progress to make the optimum droplet size by using water mist nozzles and to improve the extinguishing performance of water mist by using additives. Before this study, the extinguishing time of ethanol and n-heptane pool fire was measured with changing of water mist droplet size, flow density, discharge pressure, and fire size. In this study, on adding the additives to improve physical and chemical extinguishing performance of water mist, the extinguishing performance would evaluate and the optimum condition would find out. As a result, in case of ethanol pan 1 pool fire, the extinguishing time of the water mist by adding of 2.5 wt% NaCl and 0.3% AFFF got shorter 27% and 60% than the pure water mist. Adding of AFFF was to decrease the flame temperature by forming thin film on the fuel surface and to decrease the evaporation of n-heptane fuel. In case of NaCl, alkali salt crystals showed on the flame surface.

• Archives of Plastic Surgery
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• v.37 no.3
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• pp.227-232
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• 2010

Purpose: Continuous irrigation method is an important step in managing wound infection. V.A.C. devices have been used in intractable wounds for reducing discharge, improving local blood flow, and promoting healthy granulation tissue. We expect synergistic effects of reduced infection and more satisfactory, accelerated wound healing when using both methods simultaneously. This study evaluated continuous irrigation combined with V.A.C. appliance for treatment of infected chronic wounds. Methods: We reviewed data from 17 patients with infected intractable chronic wounds. V.A.C. device (Group A) was used in 9 patients, and V.A.C. with antibiotics irrigation (Group B) was used in 8 patients. We placed Mepitel$^{(R)}$ on the surface of wound and placed an irrigation and aspiration tube on each side. A sponge was placed on the Mepitel$^{(R)}$ and covered with film dressing. The wound was irrigated continuously with mixed antibiotics solution at the speed of 200 cc/hr and aspirated through the wall suction at the pressure of -125 mmHg. V.A.C. applied time, wound culture and wound size were compared between the two groups. Results: No complication were seen in two groups. Compared with Group A, in the Group B, V.A.C. applied time was shortened from 32.7 days to 25.6 days and showed efficacy in the reduction rate of wound size. No statistical differences were shown in bacterial reversion. Conclusion: V.A.C. appliance with continuous irrigation is an effective new method of managing infected chronic wounds and useful to reduce treatment duration and decrease wound size. Moreover it could be applied more widely to infected wound.

• Korean Journal of Materials Research
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• v.10 no.9
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• pp.601-606
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• 2000

Nickel mono-silicide(NiSi) shows no increase of resistivity as the line width decreases below 0.15$\mu\textrm{m}$. Furthermore, thin silicide can be made easily and restrain the redistribution of dopants, because NiSi in created through the reaction of one nickel atom and one silicon atom. Therefore, we investigated the deposition condition of Ni films, heat treatment condition and basic properties of NiSi films which are expected to be employed for sub-0.15$\mu\textrm{m}$ class devices. The nickel silicide film was deposited on the Si wafer by using a dc-magnetron sputter, then annealed at the temperature range of $150~1000^{\circ}C$. Surface roughness of each specimen was measured by using a SPM (scanning probe microscope). Microstructure and qualitative composition analysis were executed by a TEM-EDS(transmission electron microscope-energy dispersive x-ray spectroscope). Electrical properties of the materials at each annealing temperature were measured by a four-point probe. As the results of our study, we may conclude that; 1. SPM can be employed as a non-destructive process to monitor NiSi/NiSi$_2$ transformation. 2. For annealing temperature over $800^{\circ}C$, oxygen pressure $Po_2$ should be kept below $1.5{\times}10^{-11}torr$ to avoid oxidation of residual Ni. 3. NiSi to $NiSi_2$ transformation temperature in our study was $700^{\circ}C$ from the four-point probe measurement.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.38.2-38.2
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• 2011

폴리머 박막은 그 고유한 특성으로 인해 여러 산업적으로 널리 사용되고 있는 재료이다 예로 의약품이나 식품 포장지의 배리어, 전자부품의 절연체, 반도체 공정에서의 사용, 혹은 부식방지를 위해 사용 되어지기도 한다. 이 폴리머 박막을 증착 하기 위한 방법으로 이전부터 CVD (Chemical Vapor Deposition) 방법이 많이 사용되었고 지금까지도 가장 많이 사용되는 방법이다. CVD를 사용하여 $SiO_2$-like 필름의 증착은 전구체(precursor)로 Silane ($SiH_4$)을 사용하였으며, 플라즈마 발생 소스(source)로 열 혹은 전기장 등을 사용 하며 공정 시 압력 또한 대부분 저압 하에서 실시 하였다. 이와 같은 이전 CVD 방법의 문제는 사용되는 Silane 자체가 인체에 해로울 정도로 독성이 있으며 폭발성도 같이 가지고 있어 작업환경의 위험성이 높으며 열을 사용한 CVD의 경우 높은 공정 온도로 인해 증착 할 수 있는 대상이 제한 되어 지며 높은 열의 발생을 위해 많은 에너지의 소비가 필요하다. 저압 플라즈마를 사용한 CVD 는 공정상 높은 열의 발생이 일어나지 않아 기판 운용상 문제가 되지 않지만 저압 환경에서 해당 공정이 이루어기 때문에 인해 필수적으로 고가의 진공 챔버가 필수적이며 저압을 유지할 고가의 진공 펌프나 추가 장비들이 필요하게 된다, 또한 챔버 내에서 이루어지는 공정으로 인해 공정의 연속성이 떨어져 시잔비용 또한 많이 잡아 먹는다. 이러한 열 혹은 저압 플라즈마등을 사용한 공정의 단점을 해결하기 위해 여러 연구자들이 다양한 방법을 통해 연구를 하였다. 대기압 유전체 배리어 방전(AP-DBD: Atmospheric Pressure-Dielectric Barrier Discharge)을 사용한 폴리머 박막의 증착은 이전 전통적인 방법에 비해 낮은 장비 가격과 낮은 공정 온도 그리고 연속적인 공정 등의 장점이 있는 폴리머 박막 증착 방법 이다. 대기압 유전체 배리어 방전 공정 변수로 공급 전압 및 주파수 그리고 공급 전압의 영향, 전구체를 유전체 배리어 방전 전극으로 이동 시키기 위해 사용된 캐리어 가스의 종류 및 유량, 화학양론적 계수를 맞추기 위해 같이 포함되는 산소 가스의 유량, DBD 전극의 형태에 따른 증착 박막의 균일성 등 이 존재하며 이런 많은 변수 들에 대한 연구가 진행 되었지만 아직 이 대기압 DBD를 이용한 폴리머 박막의 증착에 대한 명확한 이해는 아직 완전 하다 할 수 없다. 본 연구에서는 이러한 대기압 DBD를 이용하여 폴리머 박막의 증착시 영향을 미치는 많은 공정 변수 등이 박막생성에 미치는 영향과 증착된 박막의 성질에 대한 연구를 진행 하였다.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.85-91
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• 2005

$SnO_2$ films were prepared at room temperature under a $(CH_3)_4Sn-H_2-O_2$ atmosphere in order to obtain transparent conductive polymer by using ECR-MOCVD (Electron Cyclotron resonance -Metal Organic Chemical Vapor Deposition) system. The electrical properties of the films were investigated as function of process parameters such as deposition time, microwave power, magnetic current power, magnet/showering/substrate distance and working pressure. An increase in microwave power and magnetic current power brought on $SnO_2$ film formation with low electric resistivity. On the other hand, the effects of process parameters described above on optical properties were insignificant in the range of our experimental scope. The transmittance and reflectance of the films prepared by the ECR-MOCVD exhibited their average values of 93-98% at wave length range of 380-780 nm and 0.1-0.5%, respectively. The grain size of the $SnO_2$ films that are also insensitive with the process parameters were in the range of 20-50 nm. On the basis of experimental data obtained in the present study, electrical resistivity of $7.5{\times}10^{-3}ohm{\cdot}cm$, transmittance of 93%, and reflectance of 0.2% can be taken as optimum values.