• Journal of the Korean Wood Science and Technology
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• 제24권4호
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• pp.56-63
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• 1996

This study was to manufacture thinned wood of Larix leptolepis Gordon into Oriented Strand Board(OSB) with Urea-Formaldehyde Resin. The OSB was made of four kinds of strand in slenderness ratio 150 ; thickness $0.3{\pm}0.05mm$, $0.4{\pm}0.05mm$, $0.5{\pm}0.05mm$ and $0.6{\pm}0.05mm$, respectively length 45mm, 60mm, 75mm and 90mm. Target densities were 0.65gr/$cm^3$, 0.75gr/$cm^3$ and 0.85gr/$cm^3$. The stepwise 9 minutes-multi-pressing schedule in the maximum pressure 40kgf/$cm^2$, the minimum pressure 10kgf/$cm^2$ was applied for $400mm{\times}390mm{\times}12mm$ board at the temperature of $150^{\circ}C$ in a hot press. In MOR The OSB of thin strand thickness $0.3{\pm}0.05mm$(length 45mm) and density 0.85gr/$cm^3$ was the highest. The strand thickness had more effect on MOR than the strand length. In strand thickness $0.4{\pm}0.05mm$(length 60mm) and density 0.85gr/$cm^3$ was the highest MOE. The strand thickness and length had adverse effects on MOE each other. At internal bonding. The OSB of strand thickness $0.3{\pm}0.05mm$(length 45mm) and board density 0.75gr/$cm^3$ showed the highest value. OSB had higher IB value with thinner strand thickness. The thinner strand thickness showed the lower thickness swelling in turn $0.3{\pm}0.05mm$(length 45mm), $0.4{\pm}0.05mm$(length 60mm), $0.5{\pm}0.05mm$(length 75mm). $0.6{\pm}0.05mm$(length 90mm). Target densities 0.75gr/$cm^3$ 0.65gr/$cm^3$, 0.85gr/$cm^3$ showed in turn lower value. Finally, The OSB made of thinned wood of Larix leptolepis Gordon showed good results in laboratory experiment.

• 대한가정학회지
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• 제27권2호
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• pp.21-30
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• 1989

The U.S. response to increased international competition was examined in the present study in order to have more comprehensive understanding of the U.S. textile and clothing market. The method employed to conduct the study was the analysis of the written materials, interview with professionals, and the survey of the actual situations of the U.S. textile and apparel industries. The results are summarized as follows; 1. Official U.S. textile and apparel trade policy has been quite has been quite protective since 1950's. The protective trend has been embodied in Japan Cotton Textile Export Control (reciprocal trade agreement signed by the U.S. and Japan in 1957), Short Term Arrangement Regarding International Trade in Cotton Textiles, Long Term Cotton Textile Arrangement (1962∼1973), and Multi-fiber Arrangement (1974∼). Other governmental programs designed to improve the competitiveness of the U.S. textile and apparel industries include Long-term Textile and Apparel Products Export-expansion Program, and 807 Trade to take labor cost advantage. 2. Along with the quite protective governmental trade policy, the corporate responses have been made such as new sourcing mixes, investment in technology, specialization in the textile and apparel industries, and recent strategies pursued by retailer's. The apparel industry was subject to pressure from imports that increased at moderate levels, and the U.S. textile and apparel industries have made extensive efforts to adjust to the increasing competition from abroad. The textile and apparel industries have taken steps to increase labor productivity through automation, to speed management to create and introduce new products and new methods, and have lowered indirect overhead costs. Several industrywide promotion campaigns have attempted to establish a greater public awareness of international competition and to develop a preference for apparel produced in the United States. 3. Regarding these response of the U.S. and other situations of world textile and apparel trade market, much of the sense of crisis that pervades Korean textile and apparel industries has to do with the problem of adjusting government and corporate policy. Textile and apparel industry of Korea faces on going pressure to reduce costs, improve quality, increase service, develop new markets, diversify, and differentiate itself from its foreign competitors. The strategies that have been adopted in the past have generally worked in the past, but the time has come to adopt strategies that reflect present conditions. If this is not done, then we stand to lose large segments of these industries, which once lost will not easily be regenerated.

• 한국지반환경공학회 논문집
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• 제19권10호
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• pp.21-26
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• 2018

흙-습윤 특성곡선은 불포화토에서 물의 흐름, 다상유체에서의 상대투수계수, 그리고 흙의 강성 및 부피 변화를 이해하는데 필수적이다. 바이오폴리머는 미생물에 완전 분해가 가능한 자연에 무해한 친환경 물질이다. 따라서, 치토산, 폴리에틸렌 옥사이드, 잔탄검, 알지네이트염 및 폴리아크릴산 등과 같은 바이오폴리머가 지반복원, 지반성능향상 및 오일생산증진을 위해 연구되어왔다. 폴리아크릴산(polyacrylic acid)은 바이오폴리머의 일종으로, 유체의 흐름 특성 향상을 통하여 오일생산증진 및 지반복원 등의 분야에서 우수한 성능을 보여왔다. 따라서, 본 연구에서는 폴리아크릴산(polyacrylic acid)을 포함한 모래의 흙-습윤 특성곡선의 이해하기 위해서 실내시험을 수행하고, 이론적 모델의 매개변수 변화를 연구하였다. 그 결과, 폴리아크릴산(polyacrylic acid)의 농도가 증가함에 따라, 포화된 모래에 주입되는 공기의 주입 모세관압력이 증가함을 보이고, 높은 모세관압력에서의 잔류 함수비 역시 증가하고 있음을 보였다. 또한, 이론식 모델의 매개변수를 구하였으며, 이를 활용한 흙-습윤 특성곡선이 실내 실험 결과와 잘 일치하고 있음을 보였다. 따라서, 이론적 모델의 매개변수를 알고 있으면, 본 연구에서 활용된 폴리아크릴산(polyacrylic acid)이외의 바이오폴리머를 포함한 모래 지반의 흙-습윤 특성곡선이 예측이 가능함을 설명하였다.

• Investigative Magnetic Resonance Imaging
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• 제19권3호
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• pp.178-185
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• 2015

Purpose: To compare the frequency of posterior globe flattening between two-dimensional T2-weighted imaging (2D T2WI) and three-dimensional (3D T2WI). Materials and Methods: Sixty-nine patients (31 female; mean age, 44.4 years) who had undergone both 5-mm axial T2WI and sagittal 3D 1-mm isovoxel T2WI of the whole brain for evaluation of various diseases (headache [n = 30], large hemorrhage [n = 19], large tumor or leptomeningeal tumor spread [n = 15], large infarct [n = 3], and bacterial meningitis [n = 2]) were used in this study. Two radiologists independently reviewed both sets of images at separate sessions. Axial T2WI and multi-planar imaging of 3D T2WI were visually assessed for the presence of globe flattening. The optic nerve sheath diameter (ONSD) was measured at a location 4 mm posterior to each globe on oblique coronal imaging reformatted from 3D T2WI. Results: There were significantly more globes showing posterior flattening on 3D T2WI (105/138 [76.1%]) than on 2D T2WI (27/138 [19.6%], P = 0.001). Inter-observer agreement was excellent for both 2D T2WI and 3D T2WI (Cohen's kappa = 0.928 and 0.962, respectively). Intra-class correlation coefficient for the ONSD was almost perfect (Cohen's kappa = 0.839). The globes with posterior flattening had significantly larger ONSD than those without on both 2D and 3D T2WI (P < 0.001; $6.14mm{\pm}0.44$ vs. $5.74mm{\pm}0.44$ on 2D T2WI; $5.90mm{\pm}0.47$ vs. $5.56mm{\pm}0.34$ on 3D T2WI). Optic nerve protrusion was significantly more frequent on reformatted 1-mm 3D T2WI than on 5-mm 2D T2WI (8 out of 138 globes on 3D T2WI versus one on 2D T2WI; P = 0.018). Conclusion: Posterior globe flattening is more frequently observed on 3D T2WI than on 2D T2WI in patients suspected of having increased intracranial pressure. The globes with posterior flattening have significantly larger ONSD than those without.

• 한국수자원학회논문집
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• 제48권3호
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• pp.149-158
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• 2015

비상방류시설은 안전한 댐 운영 및 유지관리를 위해서 절대적으로 필요한 시설임에도 불구하고 국내 댐의 경우 이를 고려한 설계가 이루어지지 않아 각 댐의 비상방류 대응 적정성을 판단하기 곤란한 상황이다. 특히 국내 댐의 경우 비상방류시설규모를 산정하는 기준이 일정치 않을 뿐만 아니라 대부분의 용수댐은 별도의 방류시설 조차도 없는 실정이다. 따라서 본 연구에서는 기존댐 방류시설 현황 분석, 국내외 비상방류시설 설계기준 등의 검토와 함께 국내 댐설계기준을 적용한 가상 댐체와 수어댐을 대상으로 수위에 따른 방류능 분석을 수행하였다. 또한 SEEP 프로그램 등을 활용, 수위저하 속도에 따른 제체의 사면 안정성을 검토함으로써 비상방류 시설의 적정규모 산정기준을 제시하고자 하였다. 이를 위하여 수리학적 해석을 통해 저류수심에 따른 제체에 작용하는 힘을 분석하였으며 수위저하 속도 변화에 따른 제체의 안정성을 검토하여 허용수위저하 속도 범위를 제시하였다. 수위 25% 저감은 하중을 50%까지 감소시켜 초기수위 저감이 중요한 것을 알 수 있었다. 가상 댐체는 물론 수어댐에 수위저하 속도 1 m/일을 적용하더라도 제체의 안전성은 보장됨을 확인하였다. 다만, 방류능과 방류 소요일수는 수위별 저류용량 등 저류지 특성과 밀접한 관계가 있어 초기대응을 위해서는 7~10일 이내에 저류수심의 25%를 먼저 방류시키고 나머지 방류량은 1~2개월 이내에 방류할 것을 제안하였다.

• 한국재료학회지
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• 제5권7호
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• pp.835-841
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• 1995

Si$_3$N$_4$가 추진기관 연소조건 하에서 흑연의 산화와 마모를 효과적으로 방지하는 다층 코팅재료로 쓰일 수 있도록 하기 위하여 저압화학기상증착법(LPCVD)으로 Si$_3$N$_4$를 코팅할 때의 증착특성에 대해 연구하였다. 흑연 위에 pack cementation방법으로 SiC를 코팅하고 그 위에 저압화학기상증착법으로 Si$_3$N$_4$를 코팅 하였으며, 증착온도와 반응기체입력비를 변화시키면서 이에 따른 증착속도와 표면형상의 변화를 관찰하였다. 증착속도는 증착온도가 높아짐에 따라 처음에는 증가하다가 최대값을 나타낸 후 감소하는 경향을 나타냈으며, 그레인의 크기는 증착온도가 높아짐에 따라 작아지는 경향을 보였다. 한편, 반응기체의 입력비가 20$\leq$NH$_3$/SiH$_4$$\leq$40인 조건에서는 증착속도의 변화나 표면형상의 변화를 관찰할 수 없었다. 증착온도 800~130$0^{\circ}C$ 범위에서 증착된 Si$_3$N$_4$가 비정질상인 것을 XRD로 확인할 수 있었으며 130$0^{\circ}C$, 질소 분위기에서 2시간 동안 열처리하여 결정상인 Si$_3$N$_4$를 인을 수 있었다.

• Korean Chemical Engineering Research
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• 제52권1호
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• pp.81-87
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• 2014

고체가 연속적으로 주입되고 배출되는 상온 상압 2단 기포 유동층(내경 0.1 m, 높이1.2 m)의 흐름특성을 조사하고, 운전유속범위를 고찰하였다. 고체는 상부 기포 유동층으로 주입되고, 넘쳐서 기계적 혹은 비기계적 밸브가 없이 단순히 농후상 고체 층으로 이루어진 고체 수송관(standpipe, 내경 0.025 m)를 통하여 하부 기포 유동층의 층으로 주입되며, 하부 유동층을 넘쳐서 고체가 배출되었다. 기체는 하부 유동층을 유동화하고 배출된 후 다시 상부 유동층을 유동화하였다. 기체로는 공기를 사용하였고, 고체로는 입도가 큰 입자(< $1000{\mu}m$, 겉보기 밀도 $3090kg/m^3$)와 입도가 작은 입자(< $100{\mu}m$, 겉보기 밀도 $4400kg/m^3$)를 혼합한 입자를 사용하였으며, 혼합비를 변수로 하였다. 하부 유동층 기체가 고체수송관의 고체흐름을 비우고, 우회하는 조건일 때 하부 유동층 유동화 속도를 붕괴속도로 정의하였다. 본 공정의 운전이 가능한 최대기체유속으로 붕괴속도가 사용될 수 있었다. 붕괴속도는 작은 입자 혼합비가 증가함에 따라 증가하여, 30%에서 가장 큰 값을 나타낸 후, 감소하였다. 붕괴속도의 경향은 고체수송관 상단과 하단 사이의 압력차 경향과 유사하였다. 붕괴속도는 벌크밀도(bulk density)와 정체층 공극률의 함수로 나타내졌으며, 벌크밀도가 증가하면 증가하고, 정체층 공극률이 증가하면 감소하였다.

• 건축역사연구
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• 제1권1호
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• pp.88-105
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• 1992

This dissertation aims to investigate the structure of Palsangjeon, a five story wooden pagoda in Pubjoo Temple which is the only wooden pagoda existing in Korea, by a comparative study of the Palsangjeon with Japanese counterparts. By doing so, the writer of the present investigation attempts to find out its structural originality. The main finding of this study are as follows. The upper part of Palsangjeon is constructed with square log frameworks called GuiTl and Sacheon-Ju around the central column. The four walls along Sacheon-Ju from the 1st level to the 3rd well resists the outside horizontal piressure. And Gui-Tl structure on the 5th level copes much better with shear force. So this frame consisting of Sacheon-Ju and log frameworks might be viewed an semi-core system, This core is supported once again by the frame of Go-Ju. That is to say. Go-Ju supports frame of Sacheon-Ju. And the frame of Pyeong-Ju on the 4th and the 5th levels also supports it. The frame of Go-Ju is supported by the frame of Pyeong-Ju on the 1st and the 2nd levels. So this structure is designed to resist the wind and also keep the balance by properly distributing vertical pressure. The plan and the elevational structure of Palsangjeon keep the balance by the perfect symmetric structure. And the frame of Sacheon-Ju forming semi-core system can resist both the lateral load and the vertical pressure for the balance of its structure. The five story pagoda in Horyuji used to stand on a central which is desigend to support the main body of the pagoda from the first level. The principles of balance is used between the Ha-Aag and short to react the rafter. Sacheon-Ju and edge column is against the lateral load. The structural jointing system is stable thanks to the log framewroks formed on every level. The five story pagoda in Horyuji poseses the structual system originated from the ancient wooden pagoda. The pagoda is found to express simple, sincere and straight forward form. On the other hand, it could be seen as a stucture resisting the earthquake and the lateral load, Palsangjeon is an excellent building which religions function is well harmonized with its structure and appearance. It not only functions extremely well as a regions place like other pagodas, but also excellently shows how multi-story wooden building should be structured.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1115-1123
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• 2008

When constructing projects such as road embankments, bridge approaches, dikes or buildings on soft, compressible soils, significant settlements may occur due to the consolidation of these soils under the superimposed loads. The compressibility of the soil skeleton of a soft clay is influenced by such factors as structure and fabric, stress path, temperature and loading rate. Although it is possible to determine appropriate relations and the corresponding material parameters in the laboratory, it is well known that sample disturbance due to stress release, temperature change and moisture content change can have a profound effect on the compressibility of a clay. The early research of Tezaghi and Casagrande has had a lasting influence on our interpretation of consolidation data. The 24 hour, incremental load, oedometer test has become, more or less, the standard procedure for determining the one-dimensional, stress-strain behavior of clays. An important notion relates to the interpretation of the data is the ore-consolidation pressure ${\sigma}_p$, which is located approximately at the break in the slope on the curve. From a practical point of view, this pressure is usually viewed as corresponding to the maximum past effective stress supported by the soil. Researchers have shown, however, that the value of ${\sigma}_p$ depends on the test procedure. furthermore, owing to sampling disturbance, the results of the laboratory consolidation test must be corrected to better capture the in-situ compressibility characteristics. The corrections apply, strictly speaking, to soils where the relation between strain and effective stress is time independent. An important assumption in Terzaghi's one-dimensional theory of consolidation is that the soil skeleton behaves elastically. On the other hand, Buisman recognized that creep deformations in settlement analysis can be important. this has led to extensions to Terzaghi's theory by various investigators, including the applicant and coworkers. The main object of this study is to suggestion the modified compression index value to predict settlements by back calculating the $C_c$ from different numerical models, which are giving best prediction settlements for multi layers including very thick soft clay.

• 한국가스학회지
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• 제20권6호
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• pp.65-72
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• 2016

천연가스용으로 개조된 가스엔진에서 방출되는 폐열을 활용하기 위한 유기 랭킨사이클 (Organic Rankine Cycle: ORC) 발전시스템을 설계 및 제작하였다. 이 연구에서는 개조된 가스엔진의 폐열을 실험적으로 분석한 데이터를 바탕으로 구성한 ORC 시스템의 컴포넌트를 설계하고 제작하였다. ORC 시스템에는 2개의 판형 열교환기와 5kW급 팽창기, 다단 펌프가 사용되었으며, 전기 히터를 이용하여 ORC 시스템의 열역학적 성능을 분석하였다. 또한, 실제로 가스엔진과 연동하여 작동 특성을 파악하기 위한 실험을 수행하였다. ORC 시스템에 열량을 공급해주는 2대의 가스엔진을 사용하였다. 열원모사실험 결과, 열원온도 $110^{\circ}C$에서 축동력 5.22kW가 발생, 압력비 7.41, 열효율 9.09%가 계산되어졌으며, 엔진연동실험에서는 고온수 온도 $86^{\circ}C$에서 축동력 2kW가 발생, 이 때의 압력비는 3.75, 열효율 6.45%가 계산되었다.