• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.460-463
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• 2003

We report the microwave reflection coefficient $S_{11}$ of copper(II)-phthalocyanine(CuPc) using a near-field microwave microscope(NSMM) in order to understand the intrinsic electromagnetic properties of organic materials. For a NSMM system, a high-quility microstip resonator coupled with a dielectric resonator was used. The reflection coefficient $S_{11}$ was changed by the preparation conditions of CuPc thin films. We compared the reflection coefficient with crystal phase, surface morphology, UV absorption spectra and x-ray diffraction results.

• Environmental Engineering Research
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• 제20권4호
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• pp.383-391
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• 2015

Transparent type noise barrier is a desirable facility since it provides a secure view to drivers and passengers. However, reflection from this type of barrier could annoy dwellers on the sides of the road. To reduce reflection noise by transparent type barrier, modification can be made to the shapes on the front side and hence get effects by distortion of sound transmission. To achieve this, we have conducted simulation by which the effects of patterned screens of noise barrier on high-ways were investigated. The reduction effects of reflected sounds were evaluated for swelling, swelling with curved, rectangular and V-shaped screen type barriers, compared to the planar panel. The emitting noise was generated by 6-lane road and the patterned noise barriers had shown the reduction effects, especially in swelling and swelling with curved type for middle height dwellers, and the V-shaped screen type for higher elevation dweller. The swelling-type showed a decrease of 0.7~1.2 dB, performing the best diminution effect among the tested noise barriers.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.799-806
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• 2004

Recently, as the forerunner in establishing the Northeast Asia's logistics base, a lot of marine engineering works such as new ports and container terminals, extension of old ports, new bridges, land reclamation etc. have been progressed. Parallel to it, there is also an increasing demand for improving the safety of construction. In this situation, high resolution seismic reflection profiling can be well used, attempting to classify rocks and sediments under water, if possible, to delineate the distribution of grain sizes in sediments not only for calculating the cost of removing sediments from harbour's channels, but also for estimating the bearing capacities for bridge or port construction. However, the results from the corresponding reflection survey that has been in operation in our country can not be effectively used for engineering purposes mostly due to the insufficient resolution. Thus. in this paper, two innovative strategies are introduced to enhance resolution. The one deals with a newly designed exploration barge that will help reduce several kinds of noises encountered electrically or operationally. The other is associated with an establishment of optimum measuring system comprising e.g. a specially devised hydrophone with a combination of 7 piezoelectric elements. Field experiments performed at Busan harbour are illustrated. The quality of acquired data was thereby fundamentally improved in comparison with that obtained at the same time in a conventional way.

• 대한전자공학회논문지SD
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• 제40권8호
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• pp.572-579
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• 2003

vertical-cavity surface-emitting laser(VCSEL) 웨이퍼에서 측정한 반사 스펙트럼을 전달 매트릭스 방법으로 계산한 반사스펙트럼과 비교함으로써 비파괴적인 방법으로 구조적인 두께 오차가 발생한 층을 찾아 내고 오차의 크기를 추정하는 방법론을 제시하였다. DBR 층의 오차를 종합하여 나타낸 n-DBR 층의 두께 오차, 즉 유효 오차를 도입하면, 반사 스펙트럼의 모양은 유효 오차에만 의존한다는 사실에 이 방법의 근거를 두고 있다. 활성층 영역의 두께 오차는 Fabry-Perot 발진파장에만 영향을 주며, 랜덤 두께 오차의 표준 편차 값이 0.005 이하일 때에 측정과 계산된 반사 스펙트럼의 비교는 신뢰성을 갖는다. 이 방법론은 VCSEL 웨이퍼 제작시 측정되는 반사 스펙트럼을 이용하므로 비파괴적이며, 0.5 nm의 두께 오차를 찾아 낼 수 있을 정도로 정밀도가 높다.

• 한국과학교육학회지
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• 제32권9호
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• pp.1405-1416
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• 2012

This study aims to analyze how pre-service science teachers' reflective thinking is presented during the microteaching process. The subjects of this study were 13 students who attended a lecture course on science teaching methods offered by the Department of Science Education of the College of Education at a national university. The simulated lessons that were performed during the microteaching process went through peer assessment and self-assessment. Then, the next set of lessons was conducted based on the assessment results. After the first set of simulated lessons, the pre-service teachers' reflection at the routine and technical levels was most remarkable in the focus dimension. In the inquiry and change dimensions, technical reflection stood out. Dialogic or transformative reflection was rarely presented. In addition, most of the pre-service teachers displayed mingling patterns of reflection levels in all of the three dimensions. The results of this study, in particular, prove that microteaching has a high level of applicability in terms of reflective thinking and instructional technology. Accordingly, there is a need for subsequent studies to create a new model that can encourage pre-service teachers' reflective thinking by structuralizing peer and self-assessment during the process of microteaching.

• 한국안전학회지
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• 제18권4호
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• pp.51-56
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• 2003

The goal of this study is to show the way to decrease the noise from air nozzles. The variables of this test are the shapes of air nozzles, air flow rate and the distance between a reflection plate and a nozzle tip. This experiment is aimed to find the most appropriate condition to minimize the noise. These are the results. If diameter ratio is more than 12:8, noise level increases by over 10 dB(A) regradless of the distance between a reflection plate and a nozzle and the existence of a reflection plate. And when $L_2$ of a nozzle is 5mm long, noise level rise relatively highly. So, it is strongly recommended that $L_2$ should be manufactured more than 10mm. The reason for a high intensity noise is that when diameter ratio is more than 12:8, the diameter of a nozzle tip($D_2$) turns small drastically, which increases the air velocity. It is assumed that when the vortes is great around the spots where a nozzle hole is suddenly smaller, great turbulent flow increases much noise.

• 한국전기전자재료학회논문지
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• 제17권6호
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• pp.641-646
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• 2004

We report the changes of the microwave reflection coefficients S$_{11}$ of copper(II)-phthalocyanine (CuPc) thin films by using a near-field microwave microscope(NSMM) in order to understand the phase transition of CuPc. For a NSMM system, a high-quality microstrip resonator coupled with a dielectric resonator was used. CuPc thin films were prepared on the pre-heated glass substrates using a thermal evaporation method. The reflection coefficients S$_{11}$ of CuPc thin films were changed by the dependence on the substrate pre-heating temperatures. By comparing reflection coefficient S$_{11}$ and crystal structures, we found the phase transition of CuPc thin films from $\alpha$-phase to $\beta$-phase at the substrate heating temperature 200 $^{\circ}C$./TEX>.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4022-4029
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• 2022

We investigated the possibility of using graphene for control of hydrogen isotopes by exploring adsorption, reflection, and penetration of hydrogen isotopes on graphene using molecular dynamics. Reflection is the dominant interaction when hydrogen isotopes have low incident energy. Adsorption rates increase with increasing incident energy until 5 eV is reached. After 5 eV, adsorption rates decrease as incident energy increases. At incident energies greater than 5 eV, adsorption rates increase with the number of graphene layers. At low incident energies (<1 eV), no isotopic effects on interactions are observed since the predominant interaction is derived from the force of π electrons. Between 1 eV and 50 eV, heavier isotopes exhibit higher adsorption rates and lower reflection rates than lighter isotopes, due to the greater momentum of heavier isotopes. Adsorption rates are consistently higher when the incident angle of the impacting atoms is smaller between 0.5 eV and 5 eV. At higher energies (>5 eV), larger incident angles lead to higher reflection and lower penetration rates. At high incident energies (>5 eV), crumpled graphene has higher adsorption and lower penetration rates than wrinkled or unwrinkled graphene. The results obtained in this research study will be used to develop novel nanomaterials that can be employed for tritium control.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.405-416
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• 2005

The rubblization technique is breaking the aged concrete pavement slab into rubblized concrete aggregate, and use it as an base material at its original position, then builds overlay above the rubblized base. This method has been successively used in USA due to the advantage of good contructibility, cost-effectiveness as well as the capability of preventing of reflection cracks. However, constructibility and economic performance of rubblization on typical Korean concrete pavements needed to be investigate since to typical Korean concrete pavements have thick slab, as well include lean concrete subbase course. This stud explored optimum breaking depth and suggested minimum 10cm based on reflection crack simulation test. Also proper head shape and impact energy were investigated based on small breaking field tests. It was found that $127kg/cm^2$ of stress with 52.3% of head contact area are breaking requirement. Also, Multi-head type breaker suitable for Korean condition was designed and developed. This multi-head type breaker was designed to rubblize old concrete to the suggested optimum rubblized-depth and rubblized-concrete-aggregate size to prevent reflection crack and maintain high bearing capacity. This machine was used for the test of rubblization of old concrete pavement on a non-use old concrete and a in-serviced road. In these two tests, engineering properties of rubblized base and constructability and cost were investigated. In both tests, the old concrete rubblized to targeted size and depth, and high-level bearing capacity was achieved. Also, superior constructability and lower cost compared with traditional reconstruction was examined.

• 지구물리와물리탐사
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• 제6권1호
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• pp.28-34
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• 2003

지반침하는 지난 3년간의 본 연구실의 중요한 연구 주제로 본 연구에서는 채굴적 붕괴로 육안상 지표침하는 뚜렷이 관측되지 않으나 그 하부 지반은 이미 교란되었다고 판단되는 영역을 천부 탄성파 반사법을 이용하여 고찰함으로써 향후 예상 침하영역을 정량적으로 도출하였다. 지반교란에 의한 탄성파 신호의 왜곡 및 감쇠를 최소화하고자 좁은 송수신 간격(0.3m) 및 가능한 짧은 오프셋(<30m)의 0.15m의 CMP간격을 가지는 측선배열로써 고주파수 천부 탄성파 자료를 획득하였다. 짧은 측선길이(43m)를 감안하여 고정된 지오폰에 대하여 송신원을 이동하는 배열법을 선택하였다. 침하에 의해 지반교란이 심한 조사지역의 탄성파 자료의 특성과 획득자료 대부분이 짧은거리 오프셋 탄성파 자료임을 고려하여 신중한 뮤팅과 잔여정보정 처리과정을 거쳐 탄성파 중합단면을 작성하였다. 지표 침하양상과 대비하여 중합단면을 해석, 정량적인 예상 침하영역을 분리하였다.