• 한국진공학회:학술대회논문집
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• 한국진공학회 2003년도 제25회 학술발표회 초록집
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• pp.214-214
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• 2003

• 한국진공학회:학술대회논문집
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• 한국진공학회 2003년도 제25회 학술발표회 초록집
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• pp.215-215
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• 2003

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2180-2182
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• 2000

Laser emission, a part of electromagnetic wave, has short propagation length in water, and the underwater applications of laser are limited. The acquisition of underwater imaging is possible only by using a blue-green laser since the blue-green range has relatively small absorption coefficient in water. We introduce the conditions of the laser required for underwater imaging and the attenuation characteristics of a blue-green laser used in water.

• 한국진공학회지
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• 제8권3A호
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• pp.181-186
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• 1999

The diffusion of oxygen atoms on tungsten (110) surface is studied by comparison of experiment results and recent calculations. It has been suggested that the thermodynamic factor which is inversely proportional to be compressibility has strong temperature dependence which may cause non-Arrhenius behavior of diffusion coefficient. Recent experiments, however, indicate effectively no temperature dependence of this factor and support the view that non-Arrhenius behavior originates from the dynamic factor rather than the thermodynamic factor. Discrepancies in coverage dependence of physical quantities between theory and experiment are discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2004년도 제26회 학술발표회 초록집
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• pp.138-138
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• 2004

• 한국진공학회:학술대회논문집
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• 한국진공학회 2004년도 제26회 학술발표회 초록집
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• pp.137-137
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• 2004

• Journal of the Korean Wood Science and Technology
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• 제35권4호
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• pp.1-8
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• 2007

목재의 방향별 내부수분이동계수와 표면방사계수를 측정하기 위하여 2.5 (방사방향) ${\times}$ 2.5 (접선방향) ${\times}$ 2.5cm (섬유방향)의 낙엽송 정육면체 시편을 제작하였다. 수분이동방향과 직교하는 단면을 제외한 나머지 4면을 파라핀테이프와 고무테이프를 이용하여 코팅한 후, 70, 50, $30^{\circ}C$의 3가지 온도조건과 30, 60%의 2가지 상대습도 조건에서 건조시키면서, 목재 내부와 표면에서의 수분이동을 평가하였다. 자유수 유동과 결합수 및 수증기의 확산에 의한 내부수분이동계수는 고온조건에서 크게 나타났으며, 섬유방향이 횡단방향에 비하여 6배, 횡단방향에서는 방사방향이 접선방향에 비하여 1.2배 정도 큰 값을 보였다. 표면방사계수는 온도가 상승하고, 표면함수율이 감소함에 따라 증가하였다. 본 연구 결과를 이용하여 비평형상태에서 낙엽송재 내 함수율 분포변화와 증발수분량을 예측할 수 있으리라 기대된다.

• 환경영향평가
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• 제32권4호
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• pp.203-213
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• 2023

우리나라 환경영향평가서의 대기모델 적용 실태를 조사하기 위하여 2021년부터 2022년까지 협의가 완료되어 환경영향평가정보지원시스템(EIASS)에 공개된 환경영향평가서를 분석한 결과 AERMOD가 89.0%로 가장 많이 사용되었다. AERMET과 AERMOD의 버전 불일치는 25.3%로 나타났으며, 산업단지 및 도시개발사업의 발생하는 오염물질 배출량 산정시 적용한 가동시간과 모델에 적용한 가동시간의 불일치는 50.6%로 나타났다. 군산지역의 단순 및 복잡지형에서 다양한 버전의 AERMET과 AERMOD 모델을 면오염원과 점오염원에 적용한 결과, AERMOD 버전 12(15181) 이후부터는 동일한 값을 나타내었다. 배출량은 24시간 가동을 기준으로 산정하고, 모델에는 주간 8시간 가동을 적용하는 가변 배출계수 옵션을 사용할 때, 예측농도는 단순 및 복잡지형에서 면오염원은 32.06~74.27%, 점오염원은 14.85~43.13% 축소되는 것으로 나타났다. 따라서 AERMOD 모델의 가변 배출계수 적용 오류를 방지하기 위해서는 환경영향평가서에 배출량 산정과정을 명확히 제시하고, 모델링 입력자료 구성에 대한 구체적인 설명이 요구되며, 환경영향평가 전문 검토기관에서는 보다 철저한 검토가 필요하다.

• 한국환경보건학회지
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• 제50권2호
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• pp.157-167
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• 2024

Background: Several previous studies have shown that commuting is a source of stress for undergraduate students. However, few studies have investigated the effect of commuting on academic stress among undergraduate students, and there has been little awareness of the environmental impact of commuting. Objectives: To evaluate the associations between commute type and/or time and academic stress among undergraduate students in South Korea, focusing on environmental sustainability. Methods: We conducted an online survey and obtained information on commute types, commute times, and academic stress from 510 undergraduate students aged ≥19 years. Academic stress was comprised of five sub-categories of stress, and total academic stress ranged from 5 to 25 points. Multiple linear regression analysis was used to analyze the associations between commute type and commute time and academic stress. Furthermore, the students were grouped into 21 categories based on their transportation mode for commuting. CO₂ emission factors per each commuting category were calculated using the transportation type's CO₂ emission data from previous studies. Spearman's correlation analysis was used to confirm the correlation between CO₂ emission factors and total academic stress. Results: Students using home-to-school transportation without transfers (vs. walking) showed a significantly higher total academic stress of 2.19 points (95% CI: 0.58, 3.80). In contrast, students using school-to-home transportation without transfers (vs. walking) showed a significantly lower total academic stress of 1.96 points (95% CI: -3.55, -0.38). Moreover, students using transportation with lower CO₂ emission factors had lower academic stress scores (home-to-school: correlation coefficient = 0.507, p<0.001; school-to-home: correlation coefficient = 0.491, p<0.001). Conclusions: Our findings suggest that both commute type and time are significantly associated with academic stress among South Korean undergraduate students. When students select environmentally-friendly transportation, they may not only improve their mental health but also improve climate resilience.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.232.2-232.2
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• 2015

Piezoelectric force microscopy (PFM) is a powerful method to characterize inversed piezoelectric effects directly using conductive atomic force microscopy (AFM) tips. Piezoelectric domains respond to an applied AC voltage with a characteristic strain via a contact between the tip and the surface of piezoelectric material. Electroactive piezoelectric polymers are widely investigated due to their advantages such as flexibility, light weight, and microactuation enabling various device features. Although piezoelectric polymers are promising materials for wide applications, they have the primary issue that the piezoelectric coefficient is much lower than that of piezoelectric ceramics. Researchers are studying widely to enhance the piezoelectric coefficient of the materials including nanoscale fabrication and copolymerization with some materials. In this report, nanoscale electroactive polymers are prepared by the electrospinning method that provides advantages of direct poling, scalability, and easy control. The main parameters of the electrospinning process such as distance, bias voltage, viscosity of the solution, and elasticity affects the piezoelectric coefficient and the nanoscale structures which are related to the phase of piezoelectric polymers. The characterization of such electroactive polymers are conducted using piezoelectric force microscopy (PFM). Their morphologies are characterized by field emission-scanning electron microscope (FE-SEM) and the crystallinity of the polymer is determined by X-ray diffractometer.