• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.872-879
• /
• 2010

High rock-fill embankment is relatively flexible, which makes crest of embankment subject to excessive amplification in displacement due to earthquake loading. To overcome problems related with site response in high embankment, it is essential to evaluate shear-wave velocity profile of the embankment with improved accuracy and reliability. In this aspect, an experimental research was performed to answer how to perform surface-wave tests and to analyze measurements at an embankment site with a sloping ground surface. Unlike flat ground surface, sloping ground may hamper and slow down propagation of surface waves due to multiple reflections and refractions in embankment. To figure out this reasoning for the effect of multiple reflections and refractions due to sloping surface, surface wave tests were performed at a reservoir embankment of Chung-Song in North KyeongSang Province. Parameters involved in surface wave tests at non-flat surface, including source directionality, geometry-related constraint and frequency components in source function, were investigated using field measurements.

• 의학교육논단
• /
• 제22권3호
• /
• pp.153-162
• /
• 2020

The aim of modern medicine is to prolong life by fighting death. Doctors have traditionally believed that this was an ethical good deed. The negative connotation surrounding death has led to the avoidance of terminally ill patients. But in a modern society where death is medicalized, doctors have to see dying patients every day and are in a state of guilt from implementing meaningless life-sustaining treatments. Therefore, medical schools should allow medical students to embrace a new perspective through death education. Yonsei University Medical College has implemented death education since 2017 as an optional class for first and second year medical students. Students watch videos related to death once a week for 6 weeks and submit their reflections by e-mail. The professor reads the students' reflections and gives them weekly feedback. Through this coursework, students realize that death is not a medical event, but rather a part of life and completion. The ultimate purpose of death education is to transform blind life-absolutist identity into narrative identity.

• 한국결정학회지
• /
• 제11권2호
• /
• pp.84-88
• /
• 2000

The crystal of cholesteryl crotylcarbonate was investigated by X-ray diffraction method. Crystallographic data for the title compound: P21, a=13.510(2)Å, b=11.843(2)Å, c=19.882(2)Å, β=106.88(1)°, Z=4. Reflections were collected with an Enraf-Nonius CAD-4 diffractometer equipped with a graphite monochromator. The structure was solved by direct methods and refined by least-squares analyses. The final R value was 0.125 for 2607 reflections. The cholesterol fragment of the title compound were in good agreement with those for related cholesterol derivatives. The molecules were stacked in clearly separated layers. At the center of the layers, there were cholesteryl-cholesteryl interactions between the symmetry-related B molecules and the cholesteryl-C(17) side chain of A molecules. There were also interactions between the C(17) side chain of B molecules and the crotylcarbonate chain in the interface region between layers. The crystal structure of the title compound turned out to be isostructural with those of cholesteryl ethylcarbonate and cholesteryl propylcarbonate.

• 소음진동
• /
• 제4권2호
• /
• pp.187-198
• /
• 1994

This study is to describe the effects of the duct termination conditions conditions upon the active noise attenuation system. The adaptive filtering algorithm using FIR filter is implemented for duct noise attenuation. To avoid the instability caused by the acoustic feedback, two methods are considered. One is to use a compensating FIR filter. The other is to utilize uni-directional detecting microphone and uni-directional control speaker. Experimental results show that the reflections of sound from duct terminations greatly reduce the performance of ANC system. The directionality of detecting microphone and control speaker is a major factor to decide ANC performance. When there are some reflections from both duct terminations, the noise attenuation using finite FIR filter is not enough to model the duct plant. Especially, the reflection from the upstream termination reduces the noise attenuation in the frequencies related to the distance between control speaker and upstream termination. The performance of the noise attenuation is found to be largely enhanced by using uni-directional coupler, both on detecting microphone and control speaker, even if the duct system has an arbitrary termination conditions.

• Journal of Electrical Engineering and Technology
• /
• 제6권5호
• /
• pp.693-696
• /
• 2011

In this work, an exponentially tapered microstrip antenna was implemented using a resistive loading technique in order to suppress the internal reflections. The inductive loading was realized by introducing slits on the antenna to improve radiation efficiency. Compared with a resistive-loaded antenna, the proposed antenna had an average improvement of about 6.2% in radiation efficiency within the range of 2-10.5 GHz. In addition, the highest peak of the radiated short pulse from the proposed antenna became 45% greater than that of an antenna with resistive loading only.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
• /
• pp.830-835
• /
• 2003

This paper describes a sonic polygonal multiple reflection range sensor (SPMRS), which uses multiple reflection properties usually ignored in ultrasonic sensors as disturbances or noises. Targets such as a plane, corner, edge, or cylinder in indoor environments can easily be detected by the multiple reflection patterns obtained with a SPMRS system. Target classification and feature data extraction, such as distance and azimuth to the target, are computed simultaneously by considering the geometrical relationships between the detected targets, and finally the environment model is generated by refining the detected targets. In addition, the narrow field of view of a sonar range sensor is increased and the scanning time is reduced by active motion of the SPMRS stepping servomechanism.

• 한국수학교육학회지시리즈A:수학교육
• /
• 제49권4호
• /
• pp.411-421
• /
• 2010

Teacher reflection as a form of professional development has been an enduring interest in education that can be traced back to Dewey. Information about how teachers interpret and analyze their students' learning would help us understand difficulties in teaching and learning. Moreover, it can be useful for teacher education by improving teaching methods. The purpose of this research was to understand how mathematics teachers reflected on their students' understanding. For the purpose of this study, I investigated four U.S.A. mathematics teachers in a middle school. In particular, I discussed Assess instances among the teachers' reflections on their students' thinking and changes of the reflections as time went by. The results showed two different types of Assess instances and shifts by time.

• 한국소음진동공학회논문집
• /
• 제12권7호
• /
• pp.520-526
• /
• 2002

Identification of noose sources, their locations and strengths, has been taken great attention. The methods that can identify noise sources normally assume that noise sources are located in a free field. However, the sound in a reverberant field consists of that coming directly from the source plus sound reflected or scattered by the walls or objects in the field. In contrast to the exterior sound field. reflections are added to sound field. Therefore, we haute to consider the reverberation effect on the source identification method. The main objective of this paper is to identify noise source in the reverberant field. At fist, we try to identify noise sources in a rigid wall emc;psire using the beamforming method. In many cases of practical interest, the wall has admittance so that random reflections occur in an enclosure. In this paper, we assumed the complex reverberant field in the enclosure to be the sum of plane caves with random Incidence and magnitude. Then we try to explain effects of reverberant field at interior source identification.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제7권6호
• /
• pp.951-963
• /
• 2015

The water wave characteristics of Bragg reflections from a train of fixed floating pontoon breakwaters was studied numerically. A numerical model of boundary discretization type was developed to calculate the wave field. The model was verified by comparing to analytical data in literature and good agreements were achieved. Series of parametric studies were conducted systematically to investigate the dependence of the reflected coefficients by the Bragg scattering on the design variables, including the spacing between the breakwaters, the total number of installed breakwaters, the draft and width do the breakwater, and wave length. Certain wave characteristics of the Bragg reflections were observed and discussed in details which might be of help for practical engineering applications in shoreline protection from incident waves.

• 반도체디스플레이기술학회지
• /
• 제18권4호
• /
• pp.154-159
• /
• 2019

Undesirable negative image is occurred in photographs taken across partial reflections such as glass window and electronic display. Efficient removing reflections given a single image are in the spotlight in recent researches. This paper discusses and evaluates two published image reflection removal algorithms, and compares the performance of time and quality of those methods with a common dataset. As benchmarking test cases are presented, we propose to modify one of the methods to reduce the run-time with small effects on the similar image quality.