• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.2
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• pp.55-60
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• 2012

In many cases, geothemal wells will not be opened up a geothermal reservoir under such conditions that an extraction of geothermal energy is economically viable without any further measures. Geothermal wells often have to be stimulated, in order to increase productivity. For the non-volcanic area, such as Korea, the hydraulic stimulation is necessary to complete geothermal power plant. The analysis of induced seismic event showed that the thermal resource might have a much wider extent and a much higher generation potential than previously assumed. In order to record compressional and shear waves emitted during fracture stimulation, three-component geophones are placed in a seismometer. The recorded data from one seismometer is the convolution of the source magnitude, the transmission media, and the sensitivity of the instrument.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.7
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• pp.629-636
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• 2011

In this study, survey experiment and EEG test was carried out to know the effect of visual images on EEG for evaluating words of soundscape sound source with 18 subjects. Analysis on the EEG were executed to know the difference according to with and without visual images. Followings are results of this study. 1) There is no big difference with visual images in soundscape sound evaluating adjectives such as "Full", "Clear", "Enjoyable" whereas there is a big difference in soundscape sound evaluating adjectives such as "Pleasant", "Comfortable", "Gentle", "Sonorous". 2) There is a tendency that soundscape sound source which is consist of single sound source shows + 1 above increase in survey test when visual image is suggested whereas soundscape sound source which is consist of one more sound source shows - 1 below decrease in survey test. 3) Statistical analysis was used to know considerable probability. ${\alpha}$-wave has a considerable probability and Maximum level difference occurring brain spots were number 1 and 2.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.715-721
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• 2018

This study examined energy saving and elevating the worker's neuro energy (comfort, concentration, physical, and psychological stability) by compensating for the unpleasant tactile sensation to stimulate auditory and olfactory senses and reduce energy consumption. The experiment was conducted in an environment test room under the test conditions of temperature $25[^{\circ}C]$, relative humidity 50[RH%], illumination 1,000[lux] and air current speed 0.02[m/sec] by stimulating the auditory senses with a 1/f change in rhythm and the olfactory senses with an aroma scent. The experiment utilized the method of EEG, which evaluates human body's psychological status via tactile means, and the method of the vibra image, which evaluates the learning abilities, HRV and human body's psychological status via non-tactile means. The subjects were selected as eight university students (four males and four females) in their 20s, the type that have high relative ${\alpha}$(8~13[Hz]) activation in occipital lobe, which brings the highest level of mind stability and concentration, who had no difficulty in physical activities. The subjects' posture and physical activity was fixed to 1met - when the subjects are seated and relaxing in a comfortable environment - and their clothes condition was standardized as 0.7clo. As a result, the sentimental and psychological stability and concentration were the highest in the multisensory stimulation of jasmine scent and change rhythm of an a=1.106 sound source. In addition, under this condition, the relative $M{\alpha}$ and relative $M{\beta}$ increased by 70.49[%] and 89.72[%], respectively; the HRT decreased by 39.09[%]; and the fatigue and tension/anxiety decreased by 36.85[%] and 15.54[%], respectively.

• The Journal of Engineering Geology
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• v.31 no.1
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• pp.67-81
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• 2021

Grouting is used for reinforcement and waterproofing of soft ground to increase its bearing capacity, reduce the impacts of rising or lowering groundwater levels, and reduce subsidence due to vibration and general causes. This study investigated the enhancement of grout strength and hardening time by the addition of reinforcing fibers, and the development of non-cement grouting materials from blast furnace slag. An experiment was performed to measure the increase in grout strength resulting from the addition of 0.5% increments of aramid and carbon reinforcing fibers. The results show that the uniaxial compressive strength of grout increases with increasing content of reinforcing fiber. Comparison of three admixtures of finely powdered blast furnace slag and 10%, 20%, and 30% calcium hydroxide stimulating agent showed that the uniaxial compressive strength of the mixture increases with increasing content of alkaline stimulant; however, the strength was lower than for 100% pure cement. The reaction of calcium hydroxide with blast furnace slag powder, which increases the strength of the grout, is more effective if injected as a solution rather than a powder.

• The Journal of the Acoustical Society of Korea
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• v.14 no.3
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• pp.5-13
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• 1995

This paper shows newly developed equations of cylindrical shell motion, which solutions are obtained as a set of linear equation. Each linear equation is derived along each axis of cylindrical coordinates. The admittance and the free wavenumber are obtained under assumption of point excition on a cylindrical shell. Their results are shown in figures. In this results, this paper shows a possibility that a vibration and a noise generated in a cylindrical shell can be formulated as a mathematical model.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.129-131
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• 2007

BLDC 모터의 진동 및 소음의 원인인 영구자석과 슬롯 개구부 형상에 의한 코깅토크를 저감시키기 위하여, RSM(Response Surface Method)과 FEM(Finite Element Method)를 이용하여 영구자석의 형상을 최적화 하였다. 최적화 과정은 총 2단계에 걸쳐 진행되었다. 1단계에서는 영구자석의 자극간격을 구하고, 2단계에서 자석의 형상을 변화시저 최적화한 결과, 최적화 전 후의 코깅도가, 최대 0.051[N.m]에서 0.029[N.m]로 약 50% 감소하였다.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.11
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• pp.943-949
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• 2005

For the psychophysical experiment of tactile perception of shapes, experimental system consists of vibrator, tactile stimulation array, measurement and control system is designed and prepared. The psychophysical experiment for the tactile perception of shape is carried out by the estimation of the subject group. Through the experiment the threshold of tactile perception to multi-stimuli with some line shape is obtained. Also the appropriate tactile stimulus intensity and frequency of the tactile stimulation array to recognize arbitrary shapes effectively are derived and discussed.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.172.1-172.1
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• 2012

위성은 발사 후 임무수행을 위하여 필수적인 자세정보를 획득해야 한다. 별 추적기는 궤도상에서 별의 위치를 파악하여 상대적인 위성의 위치를 확인하는 데에 사용하는 감지기이다. 별 추적기는 태양, 지구, 달 등의 광원으로부터 오는 빛을 차단해 주는 시야각제한기(baffle), 광학계소자(CCD) 및 렌즈, 열제어소자(cooler) 그리고 전원 및 전자박스 등으로 구성된다. 위성은 발사 전 조립시험 기간 동안 전자파, 진동, 열/진공 등의 환경시험 통하여 수차례의 성능 유무를 확인한다. 이 환경시험 전과 후에는 위성의 모든 전장품의 기능시험을 수행하여, 각 전장품의 환경영향 유무를 판별한다. 특히 벌 추적기 관련시험으로, 광학계 성능 검증을 위한 광학적 자극시험과 전자박스의 구동확인을 위한 전자박스 점검시험이 있다. 본 논문에서는 지상에서 수행한 별 추적기의 기능시험 결과를 분석하여 건정성 동향을 분석하였다.

• Progress in Medical Physics
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• v.3 no.1
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• pp.9-18
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• 1992

In this study, beta-eucryptite is fabricated and the thermal parameters of this material have been investigated. The thermoluminescence from 4MeV X-ray irradiated beta-eucryptite have been measured over the temperature range of 300K-600K. Thermoluminescence curve from X-ray irradiated beta-eucryptite shows five peaks located at 342K, 392K, 438K, 474K, and 527K. $\tau$, $\delta$ and $\omega$ of peak at 527K are 35K, 39K and 74K, respectively and this peak is found to be 2nd order kinetics. The activation energy of peak shape method is calculated to be 1.03eV and the frequency factor for 527K curve is calculated to be 3.9x10$\^$8/sec$\^$-1/. Based on the various heating rates methods, the activation energy of the peak is computed to be 1.02${\pm}$0.05eV that is similar to 1.19${\pm}$0.03eV of initial rise method. The linearity of thermoluminescence intensity and radiation flux is valid up to 50Gy and beyond higher dose the supralinearity and saturation come out.

• Progress in Medical Physics
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• v.16 no.4
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• pp.202-206
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• 2005

Three-dimensional thermoluminescence (TL) spectra from $MgAl_2O_4$ irradiated with UV light were measured over 300${\~}$600 K and 300${\~}$800 nm. The peak positions of TL glow curves were shifted to lower temperature with increasing the exposure time of UV light. The 476 K TL glow curve is due to the second kinetics and its activation energy and escape frequency factor are calculated to be 0.85 eV and $1.92{\times}10^6 sec^{-1}$, respectively The TL spectra were split into 530 nm and 700 nm emission bands which were associated with $V^{2+}$ and $Cr^{2+}$, respectively. The linearity range of 700 nm omission band is smaller than that of 530 nm emission band, but the saturation time of 700 nm emission band is longer than that of 530 nm omission band.