• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.345-346
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• 2013

InGaN material is being studied increasingly as a prospective material for solar cells. One of the merits for solar cell applications is that the band gap energy can be engineered from 0.7 eV for InN to 3.4 eV for GaN by varying of indium composition, which covers almost of solar spectrum from UV to IR. It is essential for better cell efficiency to improve not only the crystalline quality of the epitaxial layers but also fabrication of the solar cells. Fabrication includes transparent top electrodes and surface texturing which will improve the carrier extraction. Surface texturing is one of the most employed methods to enhance the extraction efficiency in LED fabrication and can be formed on a p-GaN surface, on an N-face of GaN, and even on an indium tin oxide (ITO) layer. Surface texturing method has also been adopted in InGaN-based solar cells and proved to enhance the efficiency. Since the texturing by direct etching of p-GaN, however, was known to induce the damage and result in degraded electrical properties, texturing has been studied widely on ITO layers. However, it is important to optimize the ITO thickness in Solar Cells applications since the reflectance is fluctuated by ITO thickness variation resulting in reduced light extraction at target wavelength. ITO texturing made by wet etching or dry etching was also revealed to increased series resistance in ITO film. In this work, we report a new way of texturing by deposition of thickness-optimized ITO films on ITO nano dots, which can further reduce the reflectance as well as electrical degradation originated from the ITO etching process.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.288-295
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• 1999

Nineteen japonica and Tongil-type rices were selected from seventy nine Korean and Japanese rice cultivars grown in 1989 based on the water uptake behavior of milled rice under the room temperature and boiling conditions. The selected rice cultivars were investigated for water absorbability and some physicochemical characteristics of milled rice, proper water amount for cooking and sensory evaluation of cooked rice. The relationships among the tested grain properties were also examined. The highest varietal variation of water uptake rate was observed at twenty minutes after soaking in water. The maximum water uptake of milled rices at room temperature occurred mostly at about eighty minutes after soaking in water. Newly harvested rices showed a significantly lower water uptake rate of milled rice at 20 minutes after soaking, a relatively higher maximum water absorption ratio under the room temperature, and the less water uptake and volume expansion of boiled rice compared with the one-year old rice samples. The water uptake rate and the maximum water absorption ratio showed significantly negative correlations with the K/Mg ratio and alkali digestion value(ADV) of milled rice. The rice materials showing the higher amount of hot water absorption exhibited the larger volume expansion of cooked rice. The harder rices with lower moisture content revealed the higher rate of water uptake at twenty minutes after soaking and the higher ratio of maximum water uptake under the room temperature condition. These water uptake characteristics were not associated with the protein and amylose contents of milled rice ansd the palatability of cooked rice. The water/rice ratio(in w/w basis) for optimum cooking was averaged to 1.52 in dry milled rices (12% wet basis) with varietal range from 1.45 to 1.61 and the expansion ratio of milled rice after proper boiling was averaged to 2.63(in v/v basis). The water amount needed for optimum cooking was the lowest in Cheongcheongbyeo (Tongil-type rice) and the highest in Jinbubyeo, and the amount could be estimated with about 70% fittness by the multiple regression formula based on some water uptake characteristics, ADV and amylose content of milled rice as the independent variables. Nineteen rice cultivars were classified into seven groups based on scatter diagram projected by principal component analysis using eight properties related to water uptake and gelatinization of milled rice.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.62-62
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• 2012

지구온난화 및 환경오염의 영향으로 선진국을 중심으로한 환경규제가 심해지면서, 홈 텍스타일 분야에서는 세계 패션 트렌드 및 소비자 선호에 부응한 친환경 섬유소재 개발, 웰빙 시대에 적합한 기능성 및 고감성 제품개발을 통한 차별화가 요구되고 있다. 최근의 섬유산업의 동향도 인체에 무해한 천연적인 섬유소재에 많은 관심이 증대됨에 따라 개인의 건강 뿐만 아니라 환경을 생각하는 생활패턴인 친환경섬유의 개발이 새로운 트렌드로 떠오르고 있는 실정이다. 헴프는 일년생 식물로서 학명은 Cannabis sativa L.이다. 헴프섬유의 장점으로 내구성 및 내수성, 항균성 등이 우수한 것으로 보고되고 있으나 양질의 원료 확보, 세섬도 추출 기술 및 combing 기술 등의 부족으로 100% 헴프 세 번수 방적사의 제조가 어려워 주로 면섬유와의 혼합소재로 제조되어 왔다. 최근 들어, 친환경 소재로서 박테리아 성장 억제 기능을 가진 재생섬유인 Tencel 소재를 이용하여 stiff한 Hemp의 성질에 유연성을 추가하여 촉감을 개선함과 동시에, Tencel과 Hemp를 혼용함으로써 soft touch부터 harsh touch까지 혼용율에 의한 다양한 감성을 느끼게 함으로써 용도의 다양화 추구가 시도되어 왔다. Hemp의 거친 느낌을 완화시키고 Tencel의 박테리아 억제 기능과 Hemp의 항균기능, 방충, 탈취기능이 상호 보완되어 친환경적이고 위생적인 다용도 홈 인테리어 및 가구용 직물 등의 제품으로 Hemp/Tencel 복합사가 많이 사용되고 있다. 본 연구는 Hemp와 Tencel의 혼용율의 변화에 따른 복합사의 물리적 특성을 확인하기 위하여 천연복합 태번수 방적사 최적 사설계 이론을 적용하여 Hemp 섬유 혼용율에 따른 사의 물성분석을 함으로써 Hemp/Tencel 방적사 최적 공정 조건을 결정하기 위한 사설계 이론 결과와 실험결과를 비교 분석하고자 한다. 최적 천연 Hemp복합방적사 사설계의 이론화 및 사 물성 DB화 그리고 태번수 Hemp사의 물성분석 및 이들을 DB화 함으로써 가구용 직물로 많이 사용되는 친환경 Hemp 소재사의 방적성 향상을 꾀하고자 한다. 이를 위해서 제조한 방적사의 Dry heat shrinkage와 Wet heat shrinkage를 측정하여 확인하였고 인장시험기를 이용하여 Tenacity, Initial Modulus, breaking strain을 측정 분석하였다. 방적사의 표면 특성은 영상 현미경 시스템을 사용하여 ${\times}40$ 배율로 측정하여 확인하였다.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.89-102
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• 2010

Future uncertainty on water demand caused by future climate condition and water consumption leads a difficulty to determine the reservoir operation rule for supplying sufficient water to users. It is, thus, important to operate reservoirs not only for distributing enough water to users using the limited water resources but also for preventing floods and drought under the unknown future condition. In this study, the reservoir storage is determined in the first stage when future condition is unknown, and then, water distribution to users and river stream is optimized using the available water resources from the first stage decision using 2-stage stochastic linear programming (2-SLP). The objective function is to minimize the difference between target and actual water storage in reservoirs and the water shortage in users and river stream. Hedging rule defined by a precaution against severe drought by restricting outflow when reservoir storage decreases below a target, is also applied in the reservoir operation rule for improving the model applicability to the real system. The developed model is applied in a system with five reservoirs in the Han River basin, Korea to optimize the multi-reservoir system under various future water demand scenarios. Three multi-purposed dams - Chungju, Hoengseong, and Soyanggang - are considered in the model. Gwangdong and Hwacheon dams are also considered in the system due to the large capacity of the reservoirs, but they are primarily for water supply and power generation, respectively. As a result, the water demand of users and river stream are satisfied in most cases. The reservoirs are operated successfully to store enough water during the wet season for preparing the coming drought and also for reducing downstream flood risk. The developed model can provide an effective guideline of multi-reservoir operation rules in the basin.

• Journal of Conservation Science
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• v.32 no.2
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• pp.249-259
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• 2016

Effect of the flame retardants on Dancheong is studied in the present work. Two kinds of flame retardants were applied on Dancheong specimens and compared with control groups on which distilled water was applied instead of the flame retardants. The flame retardants enhanced the hygroscopic property of the surface of Dancheong. Furthermore, the added flame retardants reacted with oyster shell white($CaCO_3$) and lead red($Pb_3O_4$), producing new chemical compounds like Calcium phosphate tribasic and Lead Phosphates which make the painted layer of Dancheong dissolving and whitening over certain period of time. When applied in excessive amount and exposed in repetitive wet and dry condition, especially, they aggravate the surface problems significantly. These results will provide a good reference on the study of the discoloring/whitening effect of Dancheong layers at many traditional wooden building in Korea.

• Journal of Conservation Science
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• v.32 no.2
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• pp.203-213
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• 2016

Conservation treatment of modern cultural heritage rickshaw from National Museum of Korean Contemporary History were carried out. The Rickshaw is divided into three parts which are chair part, sun-block cover part, wheels part. Treatment was referred to analysis results of P-XRF, species identification, FT-IR and microscope observation on Rickshaw. Outer films of rickshaw were chipped off. Therefore, conservation and restoration treatment were carried out in the damaged area. Degradation in armrest, saddle and backside of chair may cause serious problem. Therefore, the reinforcement were carried out with similar materials. Dry and wet cleaning were performed in sun-block cover to remove white stain and corrosion contaminant. Furthermore, reinforcement and restoration were performed in damaged area. Rickshaw from National Museum of Korean Contemporary History was made with various materials. This research result expects to be a great example of conservation treatment for modern cultural heritage which is made of various materials and to be used as useful data for conservation and restoration in modern cultural heritage.

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.216-222
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• 1994

This study was conducted to obtain practical information on the efficient drying of animal manure under the sunny dry condition. The effects of the height of manure pile (5, 10, 15, and 20cm), stirring times (0, 1, 2, and 4 times/day), the addition of dried manure (30%, w/w), and the type of drying bed on the removal of water from fresh pig manure were investigated in a plastic house. Pig manure was dried very well by lowering the height of manure pile and the drying efficiency was the highest at 10cm height. Water evaporation rate was the greatest at the twice stirring per day treatment. The addition of dried manure as bulking material enhanced the water evaporation rate of wet pig manure. The amounts of water removed for 19 days under the condition of 10cm height of manure pile and twice-stirring in spring, summer, autumn and winter were 75.6, 73.3, 54.6 and $32.6kg/1.2m^2$, respectively.

• The Journal of Engineering Geology
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• v.20 no.4
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• pp.381-390
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• 2010

This study assessed the hydrogeological characteristics of a seepage area of white leachate. The geological characteristics of the leachate were determined by a surface survey, and an electrical resistivity survey and borehole image processing system (BIPS) were applied to estimate the distribution of discontinuities, to assess the geological structure of the seepage areas. Fluctuations in groundwater level within boreholes were measured during periods of precipitation in the dry and wet seasons. The results show that electrical resistivity is lower in the seepage section than in non-seepage sections. The distribution of fracture zones and limestone cavities was inferred from the logging data and BIPS data. Variations in groundwater level and groundwater recharge, related to rainfall events, show the direct effect of rainfall events during the rainy season. We obtained a strong relationship between seepage amount and rainfall (correlation coefficients of 0.83-0.97).

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.3
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• pp.189-201
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• 2013

To study characteristics of the water quality in the Hansan-Geoje bay, we analyzed the long term monitoring data collected at the two sites during the period of 1987~2010. The trophic state of the waters in Hansan-Geoje bay was the mesotrophic level by the classification of Wasmud et al.[2001]. The water nutrients increased steadily from a wet season (Aug.), it reached the maximum concentration peak in a dry season (Nov.), and then decreased steadily to the winter, it reached at the minimum value in May in the next year. The result of factor analysis divided the waters of Hansan-Geoje bay into the five factors (nutrient, season, inflow land water, pollution, internal production) and the factors represented the 76.82% on the status of the waters. According to time series analysis, temperature, DO and bottom DIP were increased, and pH and COD were decreased during the period of 1987~2010. In particular, the fluctuation trend of DIN has been turned from oversupply to shortage by the N/P ratio since before and after 1990's. The water quality of the Hansan-Geoje bay has been recovered except DIP since 1987, despite of its geographical characteristic which is a general semi-closesd bay and a massive aqua-culture ground. To preserve the waters in Hansan-Geoje bay, we need to know on the cause of the increase or accumulation of DIP, and we should continue to study on the interrelation between the aqua-culture and water environment.

• Ocean and Polar Research
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• v.35 no.1
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• pp.1-14
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• 2013

Shoreline data of the barrier islands in Nakdong River Estuary for the last three decades were assembled using six sets of aerial photographs and seven sets of satellite images. Canny Algorithm was applied to untreated data in order to obtain a wet-dry boundary as a proxy shoreline. Digital Shoreline Analysis System (DSAS 4.0) was used to estimate the rate of shoreline changes in terms of five statistical variables; SCE (Shoreline Change Envelope), NSM (Net Shoreline Movement), EPR(End Point Rate), LRR (Linear Regression Rate), and LMS (Least Median of Squares). The shoreline in Jinwoodo varied differently from one place to another during the last three decades; the west tail has advanced (i.e., seaward or southward), the west part has regressed, the south part has advanced, and the east part has regressed. After the 2000s, the rate of shoreline changes (-2.5~6.7 m/yr) increased and the east advanced. The shoreline in Shinjado shows a counterclockwise movement; the west part has advanced, but the east part has retreated. Since Shinjado was built in its present form, the west part became stable, but the east part has regressed faster. The rate of shoreline changes (-16.0~12.0 m/yr) in Shinjado is greater than that of Jinwoodo. The shoreline in Doyodeung has advanced at a rate of 31.5 m/yr. Since Doyodeung was built in its present form, the south part has regressed at the rate of -18.2 m/yr, but the east and west parts have advanced at the rate of 13.5~14.3 m/yr. Based on Digital Shoreline Analysis, shoreline changes in the barrier islands in the Nakdong River Estuary have varied both temporally and spatially, although the exact reason for the shoreline changes requires more investigation.