• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1294-1303
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• 1988

Electron and hole traps in semi-insulating GaAs with activation energies ({\Delta}E_r) ranging from 0.16 $\pm$ 0.01 to 0.98 $\pm$ 0.01 eV, have been detected and characterized by photo-induced current transient measurements. SI undoped GaAs has fewer deep levels than SI GaAs: Cr. The thermal capture cross section and density of the traps have been estimated and some of the centers have been related to native defects. In particular, the activation energy of the compensating Cr, and "0" levels in semi-insulating GaAs were accurately measured. The transient measurements were complemented by Hall measurements at T > 300K and photocurrent spectra measurements. The transition energies for the deep compensating levels obtained by the analyses of data from these measurements, when compared with those from the transient measurements, indicate negligible lattice-coupling of these centers. Analysis of the transport data also indicates that neutral impurity scattering plays a significant role in semi-insulating materials at high temperatures.

• The Journal of the Acoustical Society of Korea
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• v.30 no.6
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• pp.303-307
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• 2011

This paper describes an audio watermarking using Quantization Index Modulation (QIM) on significant peaks in frequency domain. The audio signal is broken up into L samples length frames with non-overlapping and rectangular window. The zero-crossing rate of each frame is calculated for decision whether it is proper to be watermarked or not. If the frame is legitimate, frequency magnitude response is computed by discrete Fourier transform. For the QIM, we set the quantization step size based on maximum value of frequency magnitude response and select n significant peaks with w samples around them in frequency domain, totally $n{\times}(w+1)$ samples. Finally, watermark embedding is performed. Decoder extract watermarks based on Euclidean distance, that is a blind detection. The proposed method is robust against many attacks of watermark benchmark.

• The Journal of the Korea Contents Association
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• v.10 no.2
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• pp.193-201
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• 2010

Being an element of plastic arts and a language of plastic forms, the color white has significant potential for improving the quality of physical environment. Colors are dealt with scientifically in chromatics, and also often become an interesting topic when analyzing a society and its history and culture. Thus, an in-depth study of the symbolism of color white and, of white pigment are required because the color has not only an important chromatic value and this should be understood a great deal, but also been the important symbol of a culture in a particular period. This paper examined the significance of the color white identified in Asian and Western cultures based on scientific and psychological understanding of the color. This also analyzed a few major white pigments, then demonstrated different methods of using the pigments and various techniques of expression used by Asian and Western painters. In addition, the paper attempted to raise awareness of the color white as chromatic color over non-color by examining the contrasting viewpoints on the color, and the changes in the viewpoints over time and place.

• The korean journal of orthodontics
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• v.12 no.2
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• pp.139-144
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• 1982

As adhesive systems were improved, a great variety of bracket bases were available. The purpose of this study was to evaluate the adhesive porperties of 3 types of direct-bonding brackets by testing the tensile stremgth. 60 noncarious premolars extracted for orthodontic treatment were used. The tensile strength was tested by Tensilon/UTM-1-10000C after 24 hours from bonding. Following results were obtained; There was no difference between the tensile strength of foil-mesh base bracket and photoetched base bracket statisstically. However, the accurate test result of plastic bracket could not be obtained due to the distortion of bracket wing during testing. Of the failure in fail-mesh base bracket and photo-etched base bracket, the combination type of failure, where part of the adhesive remained on the tooth and part on the bracket was the most common type (50%, 50%), The second type of failure occured at the bracket-adhesive interface (30%, 35%) and the last type of failure occured at the adhesive-tooth interface (20%, 15%).

• Composites Research
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• v.17 no.5
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• pp.39-46
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• 2004

In this study, the strength of spatially reinforced composites (SRC) are predicted by using stiffness reduction for each structural element composed of a rod stiffness in each direction and a matrix stiffness proportional to its rod volume fraction. Maximum failure strain criteria is applied to rod failure, and modified Tsai-Wu failure criteria to matrix failure. The material properties composed of the tensile failure strain of a rod, the compressive failure strain of 3D SRC, the tensile and compressive strength of the 3D SRC in the $45^{\cir}$ rotated direction from a rod and the shear strength of the 3D SRC are measured to predict the SRC strength. The strength distributions of the 3D/4D SRC in rod and off-rod direction have the largest and the smallest values, respectively. A variable load step is selected to increase an efficiency of strength distribution calculation. Uniform load step is applied when a load history is needed. The results of compressive strength from analysis and experiment show the 18 % difference though the initial slop is coincident with each other.

• 한국해양학회지
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• v.15 no.2
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• pp.123-128
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• 1980

Variabilities of tidal range at Inchon were described based on observed values. Relationships between tidal ranges and harmonic costants of tide were also examined. Fortnightly variation is predominant and its range is 571.3cm. Mean of maximum spring range(ΔH/sun max/) is 887.2cm and that of minimum neap range(ΔH/sun min/) is 315.9cm. Mean tidal range(ΔH) is 634.3cm. Diurnal inequality is shown about 141cm on an average and monthly inequality is also shown about 100cm. Yearly inquality appears with a range of about 35cm, maxima in March and September, and minima in June and December. There may exist 18 1 years periodicity with a range of about 45cm. There are some relationships between ridal ranges and amplitudes of M$\_$2/ and S$\_$2/, such as ΔH=2.172 H$\_$m/, ΔH$\_$max/=3.043 H$\_$m/, ΔH$\_$min/=1.071 H$\_$m/, ΔH$\_$max/=2.198 (H$\_$m/ + H$\_$s/), and ΔH$\_$min/=1.740 (H$\_$m/ - H$\_$s/).

• The Korean Journal of Mycology
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• v.25 no.3 s.82
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• pp.161-166
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• 1997

Occurrence of Hypoxylon truncatum, known as a symbiont of white jelly mushroom, was first noted and described in Korea. Two stromatal forms reported in North American collections of H. truncatum sensu Miller were also observed in Korean collections. Based on evidences from other studies, polymorphic patterns seen in six enzyme digestions of nuclear Internal Transcribed Spacer (ITS) regions of Korean isolates indicated that the two stromatal forms were genetically distinct. Because there was a clear association of stromatal morphology with genetic differences, the different stromatal forms might be different species. In addition, clear species concept on the species H. truncatum would provide aids in selecting proper strain for cultivation of white jelly mushrooms.

• Fire Science and Engineering
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• v.14 no.1
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• pp.8-12
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• 2000

We had investigated thermal and ignition behaviors of textiles. Decomposition of textiles with temperature was investigated using a DSC and the weight loss according to temperature using a TGA in order to find the thermal hazard of textiles, and the ignition behaviors of textiles according to species and permeation amount of oil. In addition, ignition behaviors of those permeated into oils indicating different iodine value and of those with arid without air in reaction vessel of measuring equipment were studied with constant temperature method among ignition temperature measuring methods. As results, the range of decomposition temperature of synthetic fiber was slightly broad compared with that of natural fiber, pure cotton. Besides, the initiation temperature of heat generation of both samples riced in the case of no air injection in the reaction vessel. On the other hand, in the case of air injection that was lowered according to the increase in permeative amount of oils and fats and decreased quickly as sample was permeated into drying oil.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.102-102
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• 1999

6Mo급 슈퍼 스테인리스강의 내식성은 여러 환경에서 여러 가지의 부식 시험 방법을 통해서 확띤되어 왔다. 이 합금이 보이는 탁월한 내식성 때문에 해수 설비 계통,정유 설비,원자력 발전소의 열교환기 등의 중요 재료로서 그 사용 용도가 급격히 증가하고 있다. 그런데 방사선의 영향을 받게 되는 설비에 금속 재료가 사용되는 경우,특히 경수로의 노내 구조물, 액체 금속로의 열교환기, 핵융합로의 제1벽 재료 등 에서는 합금 원소가 방사성 환경에 의하여 제거되는 현상이 나타난다. 따라서 본 연구에서는 이러한 상황을 미리 재료 제조 차원에서 모사하여 탄소량과 질소량의 함량 을 달리 한 6Mo급 슈퍼 스테인리스강을 제조하여 미세 조직, 기계적 성질 및 부식 특성의 변화에 대하여 연구하였다. 진공 고주파 유도 용해로를 이용하여 탄소량과 질소량이 각기 변화된 슈퍼 스테인리스강을 용해 한 뒤 아르곤 가스 분위기에서 $1180^{\circ}C$로 soaking하고 열간 압연을 행하였다. 열간 압연으로 표변에 생성된 산화 스케일을 불산과 질산의 혼합 용액으로 제거한 뒤 냉간 압연을 행하였다. 이 냉연 판재에 대하여 $1150^{\circ}C$로 소둔하여 각 실험에 사용하였다. 광학 현미경을 이용하여 미세 조직의 변화를 관찰하였으며, 상온과 고온($520^{\circ}C$)에서 인장 시험을 행하였으며, 경도 측정을 행하였다. 또한 양극 분극 시험과 비등 질산 침지 시험 및 비등 40% NaOH 용액에서의 일정 연신율 시험을 행하 였다. 탄소 함량이 증가할수록 항복 강도 및 인장 강도는 증가하고 있으며 연신율은 감 소하는 일반적인 경향을 보였으며 비등 질산 시험에서는 탄소량에 관계없이 매우 우수한 내식성을 쁘였다. 또한 비등 상태의 40% NaOH 용액에서의 응력 부식 균열 시험 결과, 탄소량이 증가할수록 부식 저항성이 증가하고 있는 것으로 평가되었다. 한 편 질소량이 증까할수록 결정립이 미세화되었으며 경도값이 상승하였다. 이들 합금 에 대한 양극 분극 시험 결과, 질소량의 변화가 탄소량의 변화보다 내식성에 큰 영향 을 미치고 있음을 알 수 있었다.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.285-288
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• 2008

This study aims to rout optimized design flood discharge through prediction of the frequency-based precipitation from the frequency analysis with density of rainfall gage networks in urban watershed. Frequency analysis was examined for the measured rainfall depth with low density of a point and high density of the sub-basin divided into 13 points in watershed. The used rainfall data in order to analyze consists of two groups based on measured rainfall depth for a day duration with 39years of a point and 6years of 13 points by an extending as annual exceedance series, respectively. Selected rainfall data in this analysis show that low-network has maximum rainfall depth with duration 1hr-79.1mm and 24hrs-329.1mm, and high-networks have ones with duration of 1hr-93.0 mm and 24 hrs-245.0 mm, respectively. As the result, probability of the best in this study determined the Gumbel method from the goodness of fit test and the method of prime 6 probability distributions.