• 대한토목학회논문집
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• 제13권1호
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• pp.141-149
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• 1993

순수한 위성모델의 조화상수와 지상중력을 조합하여 남한지역에서의 측지기준계 1980(GRS80) 중력지오이드가 산정되었다. Stokes적분의 영역으로는 측점증력을 사용한 $20^{\prime}{\times}20^{\prime}$의 인접범위와 $10^{\prime}{\times}10^{\prime}$ 평균중력을 사용한 $2^{\circ}{\times}2^{\circ}$의 중간범위, 그리고 GEM9 조화상수를 GRS80 기준계로 변환하여 구한 $1^{\circ}{\times}1^{\circ}$평균중력을 외곽범위에 적용하였다. 경계영역을 ${\psi}_0=30^{\circ}$로 한 Stokes 적분의 결과에서는 OSU89B 모델과 약 2~3m 의 차이가 있으며 이는 $1{\times}10^{-6}$ 인 프리에어 지오이드로서 만족됨을 보여주고 있다.

• 한국자동차공학회논문집
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• 제17권5호
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• pp.39-45
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• 2009

An experimental research with 2.0 liter 4-cylinder turbocharged diesel engine was carried out to investigate the combustion and emission characteristics for various alternative fuels. The conventional diesel fuel, neat GTL, blends of 80% of GTL and 20% of biodiesel derived from waste cooking oil are utilized without any modification of engine hardware and ECU data. For GTL and blends of GTL/biodiesel fuel, the ignition delay decreased at the same operating conditions, and overall combustion duration increased slightly. Also, the peak cylinder pressure increased for blends of GTL/biodiesel compared to diesel and GTL fuel. THC and CO emissions with blends of GTL/biodiesel compared to other fuels decreased for the low and middle load conditions. But NOx emission increased due to oxygen content in biodiesel. The number concentrations of PM are higher for blends of GTL/biodiesel than other test fuels in the nucleation mode, while it had an opposite tendency in the accumulation mode, which implies more reduction of PM for blends of GTL/biodiesel on the base of mass concentration.

• Mass Spectrometry Letters
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• 제7권2호
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• pp.50-54
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• 2016

Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is currently used in our laboratory for isotopic and quantitative analyses of nuclear materials at ultra-trace levels in environmental swipe samples, which is a very useful for monitoring undeclared nuclear activities. In this study, to improve measurement precisions of uranium isotopes at ultratrace levels, we adopted a desolvating nebulizer system (Aridus-II, CETAC., USA), which can improve signal sensitivity and reduce formation of uranium hydride. A peristaltic pump was combined with Aridus-II in the sample introduction system of MC-ICP-MS to reduce long-term signal fluctuations by maintaining a constant flow rate of the sample solution. The signal sensitivity in the presence of Aridus-II was improved more than 10-fold and the formation ratio of UH/U decreased by 16- to 17- fold compared to a normal spray chamber. Long-term signal fluctuations were significantly reduced by using the peristaltic pump. Detailed optimizations and evaluations with uranium standards are also discussed in this paper.

• 지역사회간호학회지
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• 제24권2호
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• pp.123-134
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• 2013

Purpose: The prescription drug list for primary treatment by community health practitioners has been maintained for 30 years without any modification. Thus, this study will suggest an improvement scheme of prescription drug list for primary health care posts through an analysis of drug use in those posts. Methods: A questionnaire survey was implemented with community health practitioners from April to June in 2012. A total of 1,249 copies were analyzed. As for the databases of drug use in the integrated information, a total of 154,229 diagnoses selected in the method of stratified cluster sampling from 39 primary health care posts' data were analyzed. We consulted some experts about the prescription medication list, and referred to the medication information on-line home page for up-to-date drug information. Results: This study ultimately suggests 77 prescription drug items for primary health care posts by eliminating 35 items and replacing 1 item from the original list, and adding 4 items to it. Conclusion: This study will provide basic data for revising the prescription drug list in primary health care posts by periodically reflecting adverse effects in the existing drugs, demographic and environmental changes, and development of new drugs.

• 조명전기설비학회논문지
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• 제23권1호
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• pp.18-26
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• 2009

최근, 에너지 절감 및 환경보전의 한 방법으로서 LED광원을 이용한 고효율 조명기기의 요구가 증가하고 있다. 그러나 LED광원을 이용한 조명기기는 실내공간의 용도 및 사용자에 대한 고려를 배제한 채, 색상 및 패턴이 결정되어 시각적 불쾌감을 초래하고 있다. 이에 본 연구는 LED광원을 이용한 국부조명의 CCT의 변화가 작업자의 시작업 성능에 미치는 영향을 분석하여 실내공간의 용도 및 사용자를 고려한 조명 설계에 기초자료를 제시하고자 한다. 본 연구를 위해 2 종류의 LED광원과 1종류의 형광광원을 선정하였으며, 대학생 30명을 대상으로 오류수정작업과 읽기작업에 대한 정확도 및 소요시간을 평가하였다. 시작업 성능평가 결과, LED광원에서 오류수정 작업의 정확도는 형광광원에 비해 최대 2.5[%]가 증가되었으며, 소요시간은 최대 17.1[%]가 감소되었다. 또한 읽기작업 결과 소요시간은 LED광원에서 20.6[%]가 감소하였다.

• Wind and Structures
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• 제26권6호
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• pp.397-413
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• 2018

Excitation mechanism of interference effect between two tall buildings is investigated with wind tunnel experiments. Synchronized building surface pressure and flow field measurements by particle image velocimetry (PIV) are conducted to explore the relationship between the disturbed wind flow field and the consequent wind load modification for twin buildings in tandem. This reveals evident excitation mechanisms for the fluctuating across-wind loads on the buildings. For small distance (X/D < 3) between two buildings, the disturbed flow pattern of impaired vortex shedding is observed and the fluctuating across-wind load on the downstream building decreases. For larger distance ($X/D{\geq}3$), strong correlation between the across-wind load of the downstream building and the oscillation of the wake of the upstream building is found. By further analysis with conditional sampling and phase-averaged techniques, the coherent flow structures in the building gap are clearly observed and the wake oscillation of the upstream building is confirmed to be the reason of the magnified across-wind force on the downstream building. For efficient PIV measurement, the experiments use a square-section high-rise building model with geometry scale smaller than the usual value. Interference factors for all three components of wind loads on the building models being surrounded by another identical building with various configurations are measured and compared with those from previous studies made at large geometry scale. The results support that for interference effect between buildings with sharp corners, the length scale effect plays a minor role provided that the minimum Reynolds number requirement is met.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2005년도 추계학술대회지
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• pp.35-39
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• 2005

울산항은 제1항로와 제2항로, 제1항로와 제3항로의 분기점에서 해상교통흐름이 교차하고 있고, 1항로접근수역 및 관절곶 해역에서 교통흐름이 교차하고 집중하고 있다. 또한 현재 49선석에서 2011년 29개 선석의 추가개발로 수역시설에 대한 조정 등이 필요할 것으로 판단된다. 본 연구에서는 울산항 인근해역에 대한 자연환경, 해양사고, 해상교통량 및 해상교통흐름 관측, 어업현황 등을 조사 분석하고, 전문가 및 이용자에 대한 설문조사를 실시하여 개선안을 도출하고자 한다.

• Journal of the Korean Wood Science and Technology
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• 제41권3호
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• pp.187-200
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• 2013

본 연구에서는 목재보존제의 최근 국제적 동향 중, 비 구리계 약제를 중심으로 조사되었다. 최근의 목재보존제 연구 분야에서 다루어지는 비 구리계 약제로는 환경친화적 수용성약제 성분의 대표적인 붕소계 화합물이 가장 많았고, 자연에서 얻어지는 천연물질을 이용한 약제, 화학처리목재, pyrethroid계 방충제 등이 포함되었다. 인축 및 환경에 대한 사용안전성이 고려된 약제들이 주 연구대상이 되는 경향이 있었다. 붕소의 경우에는 옥외 사용 시 물에 대한 용탈성을 개선하기 위하여 다양한 고분자 등의 물질을 도입하여 정착성을 높이고자 하는 연구들이 주요 이슈였다. 또한 의학 분야에서 많이 다루어지던 천연물질이 목재보존제로써 사용하고자 하는 시도와 치수안정성을 목적으로 개발되었던 아세틸화 목재와 같은 화학수식목재에 대한 옥외 사용 시도가 눈에 띄게 증가된 경향을 나타내었다.

• Journal of Forest and Environmental Science
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• 제36권3호
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• pp.219-224
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• 2020

Urea formaldehyde resins are widely used in the manufacturing of wood composite and their usage is always combined with release of formaldehyde characterized to be hazardous to health during and after the manufacturing of the products. This study investigates the effectiveness of wood-based adhesive from oil of pyrolysed Triplochiton scleroxylon sawdust for the production of composite board. The wood-derived Pyrolytic Oil (PyO) was blended with Urea Formaldehyde (UF) resin to formed Pyrolytic Oil-Urea Formaldehyde (PyOUF). The obtained PyOUF called Wood-Based Adhesives at four blends and control (UF) viz; 1:1, 1:2, 1:3, 2:1, 1:3 were further employed to prepare the composite board and test for their bonding strength by physical (water absorption-WA and thickness swelling-Th.S) and mechanical properties (modulus of elasticity-MOE, modulus of rupture-MOR, and impact bending-IB). Data obtained was analysed using analysis of variance at α 0.05. The result of analysis of variance conducted on physical properties show significant difference (p≤0.05) between the WA values obtained when testing the different blending proportion of PyOUF and likewise between 2 and 24 h of immersion. PyOUF had significant effect (p≤0.05) on Th. S for 24 h but no significant different (p>0.05) for the 2 h period of soaking. The analysis of variance on mechanical properties of the composite board (MOE, MOR, and IB) show significance differences (p≤0.05) between the strength values obtained when testing the different ratios of PyO with UF. PyO content influenced the properties of the boards and it is evident that PyO can be used in the manufacture of composite board.

• Journal of Forest and Environmental Science
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• 제36권3호
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• pp.225-232
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• 2020

Chemical modification of wood is an effective method to enhance the biological durability of wood with no toxic effect on the environment. In this study, wood of Triplochiton scleroxylon was modified using acetylation techniques. A total of one hundred wood blocks, (each 20×20×60 mm) obtained from a 22-year old T. scleroxylon tree were conditioned and acetylated at 120℃ in a bioreactor containing acetic anhydride for 60, 120, 180, 240 and 300 minutes. The percentage weight gain of acetylated wood was determined. The untreated (control) and treated blocks were exposed to Pleurotus ostreatus (white rot fungus) and Fibroporia vaillanti (brown rot fungus) after which moisture content (MC) and weight loss (WL) was monitored for 16 weeks. Data were analysed using descriptive and inferential statistics at p<0.05 level of significance. The percentage weight gain of acetylated wood samples increased with time from 10.4% (60 minutes) to 22.7% (300 minutes). MC of untreated blocks inoculated with Pleurotus ostreatus was significantly higher than those of Fibroporia vaillantii after 16 weeks exposure. There was no significant difference in the MC of the of the acetylated samples for the two fungi after 300 minutes reaction time. The WL of untreated blocks inoculated with Fibroporia vaillantii was higher than those of Pleurotus ostreatus, however, the two fungi showed no significant difference in the WL for the acetylated samples after 16 weeks exposure. Acetylation prevents moisture absorption and inhibition of fungi growth in acetylated wood compared to untreated wood, thereby enhancing the durability of Triplochiton scleroxylon.