• 한국항만학회지
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• 제12권2호
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• pp.269-280
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• 1998

A Wave-induced current model is developed in our study and this model is composed with wave transform model and current model. Two types of wave model are used in our study one is Copeland(1985) type which is applied in the offshore region and the other is Watanabe and Maruyama(1984) type which is applied in the surf zone. The depth-integrated and time-averaged governing equation of an unsteady nonlinear form is used in the wave induced current model. Lateral mixing radiation stresses surface and bottom stresses are considered in our current model. Copeland’s(1976) is used as a surface friction formula. Numerical solutions are obtained by Leendertse scheme and compared with Noda’s(1974) experimental results for the uniform slope coastal region test and Nishimura & Naruyama’s (1985) experimental results and numerical simulation results for the detached breakwater. The results from our wave model and wave model and wave-induced current model show good agreements with the others and also show nonlinear effects around the detached breakwater. The model in this study can be applied in the surf zone considering the friction stresses.

• 동의생리병리학회지
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• 제28권6호
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• pp.674-682
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• 2014

The purpose of this study was to identify the effect of applying oriental music therapy and reliability of electroencephalogram(EEG) equipment. The study was approved by the critical trial judge committee from ${\bigcirc}{\bigcirc}$(IRB No. 2013-07) university. In order to measure test-retest reliability for 15 subjects, EEG for same participants were measured using same method mentioned above after 2 hours from the first measurement. Same provider implemented to each person at same time. Firstly, EEG was measured for 5 minutes after the subject with attached electrodes sat on chair comfortably for 10 minutes. Then, the subject was given mental stress using the four fundamental arithmetic operations for 5 minutes, and measured EEG for another 5 minutes. After that the subject sat on the chair comfortably listening oriental medicine music therapy for 5 minutes, and EEG was measured for 5 minutes again. There was no side effect regarding music therapy reported. Raw data, which was measured in each step, were converted through FFT(fast fourier transform) and analyzed after divided into certain frequency including ${\alpha}$ wave, ${\beta}$ wave, ${\theta}$ wave, immersion wave, stabilization wave, sef100 wave, and sef95 wave. Data were analyzed using wilcoxon signed rank test, Intraclass correlation coefficient(ICC), repeated measures ANOVA with the SPSS program. In test-retes method, there were significantly differences in ${\alpha}$ wave, ${\beta}$ wave, immersion wave, stability wave, ${\theta}$ wave, sef100 wave, sef95 wave. ICC has shown a high degree of reliability that it was ${\alpha}$ wave .877, ${\beta}$ wave .855, ${\gamma}$ wave .895, immersion wave .897, stability wave .816, ${\theta}$ wave .904, sef100 wave .910, sef95 wave .776. Also, there was a statistically significant difference in ${\alpha}$ wave after applying oriental music therapy. Based on these results, it is considered that average of the channel EEG and application of oriental music therapy would be practiced by increase of sample size using this machine.

• 가정과삶의질연구
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• 제26권4호
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• pp.13-25
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• 2008

This study of a music therapy program for the 18 subjects residing in Jeollanam-do province was conducted two times per week during 4 months totalling 17 times in order to evaluate the reduction of the characteristics of patients suffering from stress disorder patients such as depression, and anxiety, Though the experiment for non-symmetric level the concentration and appearance of Alpha wave were determine to be stable but the findings from non-symmetric level according to the left-right brain activity were not significant for T-test, though its effective intermission of music therapy due to variation of the mean values was demonstrated, and the variation of the Alpha wave appearance rate was also significant for the statistics of the T-test for the effectiveness of the music therapy. And for the reduction of depression, emotion, and state-trait anxiety between groups divided into the control group and the experiment, pre-measurement and post-measurement comparisons through psychological tess, validated the effectiveness of music therapy for Posttraumatic stress disorder patients. First of all, this study was conducted in the situation of scarce study cases and program developments for the efficacy of music therapy for the patients suffering from Posttraumatic stress disorders without precedent studies of scientific identification through brain wave measurement. Because this study is insightful in the context of validating the efficacy of musical treatment, we expect that these kinds of studises will be continued.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.743-748
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• 1998

As nation's infrastructure is getting old, nondestructive evaluation of existing structures and construction quality control are getting important. In this thesis, flaw detection techniques of concrete members with asphalt using impact echo test were introduced. This techniques are based on stress wave propagation. In this field impact echo test, As load is gradually increased, frequency is increased. From this change of frequency through impact echo test, we can detect that the crack of bridge ascends and what the depth of crack is.

• Steel and Composite Structures
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• 제48권1호
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• pp.27-41
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• 2023

Under the long-term effect of corrosive environment, many cold-formed steel (CFS) structures have serious corrosion problems. Corrosion leads to the change of surface morphology and the loss of section thickness, which results in the change of instability mode and failure mechanism of CFS structure. This paper mainly investigates the elastic local buckling behavior of corroded CFS columns. The surface morphology scanning test was carried out for eight CFS columns accelerated corrosion by the outdoor periodic spray test. The thin shell finite element (FE) eigen-buckling analysis was also carried out to reveal the influence of corrosion surface characteristics, corrosion depth, corrosion location and corrosion area on the elastic local buckling behaviour of the plates with four simply supported edges. The accuracy of the proposed formulas for calculating the elastic local buckling stress of the corroded plates and columns was assessed through extensive parameter studies. The results indicated that for the plates considering corrosion surface characteristics, the maximum deformation area of local buckling was located at the plates with the minimum average section area. For the plates with localized corrosion, the main buckling shape of the plates changed from one half-wave to two half-wave with the increase in corrosion area length. The elastic local buckling stress decreased gradually with the increase in corrosion area width and length. In addition, the elastic local buckling stress decreased slowly when corrosion area thickness was relatively large, and then tends to accelerate with the reduction in corrosion area thickness. The distance from the corrosion area to the transverse and longitudinal centerline of the plate had little effect on the elastic local buckling stress. Finally, the calculation formula of the elastic local buckling stress of the corroded plates and CFS columns was proposed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.675-678
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• 2004

The importance of predicting concrete compressive strength of in concrete structures is gradually increasing in construction industry. The estimation of concrete compressive strength of is a critical factor of the construction schedule and quality control. This study was performed to examine the relationship between concrete compressive strength and stress wave velocity which was determined by the impact echo method and SASW method.

• 한국화예디자인학연구
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• 제43호
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• pp.57-79
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• 2020

본 연구는 원예치료 기반 직업재활 프로그램이 정신장애인의 정서 및 뇌파에 미치는 영향을 알아보고자 실시하였다. 연구는 경상북도 G시 보건소의 직업재활반 정신장애인 회원 3명을 대상으로 진행하였다. 연구 결과 대상자 모두 정적 정서는 증가, 부적 정서는 감소되었다. 뇌파 검사 결과 대상자 A는 세타파가 사전 17.27%, 사후 21.39%, 알파파가 사전 39.66%, 사후 49.02%, SMR파가 사전 13.53%, 사후 18.49%, 중간베타파가 사전 39.72%, 사후 41.53%로 증가, 베타파가 사전 27.53%, 사후 17.54%, 고베타파가 사전 46.75%, 사후 39.98%로 감소하였다. 대상자 B는 알파파가 29.70%, 사후 31.82%, 중간베타파가 사전 44.24%, 사후 65.76%로 증가, 고베타파가 사전 29.04%, 사후 9.09%로 감소하였다. 대상자 C는 알파파가 26.30%, 사후 49.42%, SMR파가 사전 19.86%, 사후 20.59%로 증가, 베타파가 사전 29.85%, 사후 16.13%로 감소하였다. 아이디어, 창조적 사고가 발생하는 세타파와 안정 상태, 집중, 학습에 몰두할 때 나타나는 알파파, SMR파, 중간베타파는 증가, 스트레스, 긴장, 불안 시 발생하는 베타파, 고베타파는 감소하였다. 수익금 분석 결과 대상자 A는 101,700원, 대상자 B는 81,000원, 대상자 C는 56,200원의 수익을 얻었다.

• Geomechanics and Engineering
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• 제30권5호
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• pp.449-460
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• 2022

Safe underground construction in a rock mass requires adequate ground investigation and effective determination of rock conditions. The estimation of rock mass behavior is difficult, because rock masses are innately anisotropic and heterogeneous at different scales and are affected by various environmental factors. Quantitative rock mass classification systems, such as the Q-system and rock mass rating, are widely used for characterization and engineering design. The measurement of rock classification parameters is subjective and can vary among observers, resulting in questionable accuracy. Geophysical investigation methods, such as seismic surveys, have also been used for ground characterization. Torsional shear wave propagation characteristics in cylindrical rods are equal to that in an infinite media. A probabilistic quantitative relationship between the Q-value and shear wave velocity is thus investigated considering long-wavelength wave propagation in equivalent continuum jointed rock masses. Individual Q-system parameters are correlated with stress-dependent shear wave velocities in jointed rocks using experimental and numerical methods. The relationship between the Q-value and the shear wave velocity is normalized using a defined reference condition. This relationship is further improved using probabilistic analysis to remove unrealistic data and to suggest a range of Q-values for a given wave velocity. The proposed probabilistic Q-value estimation is then compared with field measurements and cross-hole seismic test data to verify its applicability.

• 비파괴검사학회지
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• 제9권1호
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• pp.48-55
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• 1989

It is desirable to develop the effective NDT techniques to evaluate the strength of composite structures. In this study several of acoustic NDT techniques were applied to investigate useful parameters for evaluating the filament wound GFRP structures and following results were obtained. 1. Propagation velocity of stress wave to axial direction in the filament wound GFRP pipe depends on the effective modulus along the propagation direction and source location was parcticable from the a measured velocities. 2. By the application of acoustic emission techniques to GFRP pipe during hydraulic test, it was proven to be possible to detect the damage initiating pressure which could be evaluated nondestructively through the measuring of stress wave energy factor(SWEF). 3. The final failure pressure of GFRP was greatly influenced in the presence of pass through defects, and void-like defects were more dangerous than the laminar type defects.

• International Journal of Safety
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• 제1권1호
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• pp.7-12
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• 2002

This paper demonstrates the impact stresses and wave propagation characteristics of glass/epoxy laminates subjected to the low-velocity impact by a steel ball theoretically and experimentally. A plate finite element model in conjunction with experimental contact laws is used for the theoretical investigation. The specimens for statical indentation and impact test are composed of $[0/45/0/-45/0]_28 and [90/45/90/-45/90]_28$ stacking sequences and have clamped-simply supported boundary conditions. Finally, these two results are compared and then the impulsive stress and wave propagation characteristics of this laminated composite are studied.