• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.48-52
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• 1992

진동원을 가진 장비를 임의의 구조물에 설치할 경우 관심이 되는 문제는 구 조물의 임의의 위치에서의 진동 수준을 추정하는 일이다. 특히 정밀장비를 다루는 반도체 공장에서 크린룸이나, 정밀측정, 분석 실험실등 미진동을 제 어해야 하는 분야에서는 더욱 그 필요성이 대두되고 있다. 진동제어가 필요 한 공간에 대한 진동수준의 예측이 가능할 경우 진동윈이나 수진점(active and passive type)방진에서 최적화된 전달률(transmissibility)을 명확히 결정 할 수 있어 설계와 시행오차를 최소화 할 수 있다. 그러나 이러한 실제문제 를 다룰 경우 대부분 진동제어 구조물은 복잡하고 설치 운용되는 장비들은 대형, 복합장비가 사용되는 것이 일반적이고 수행기간도 여러가지 공정상 단 시간에 이루어져야 하는 현실적인 어려움이 있다. 진동제어가 필요한 구조물 에 대한 임의의 공간에서 진동수준을 신속하고 정확하게 예측하기 위해서는 최소한 두 가지 정보만이라도 명확히 해야 한다. 하나는 장비의 주파수별 정 확한 가진력의 산정이고 다른 하나는 장비가 설치되고 진동제어가 필요한 구조물에 대한 동적특성(dynamic property)이다. 가진력에 대한 정보는 일반 적으로 장비제작사가 제시하는 것이 원칙이나 그렇지 못할 경우 구조해석 기술자(structure engineer)가 해석적으로 추정하거나 또는 명확히 가진 특성 을 알지 못하는 복잡한 장비는 실험적으로 결정해야 한다. 구조물의 동적 특 성을 나타내는 모빌리티(mobility)를 구하는 방법은 해석적인 방법과 실험적 인 방법이 있으나 복합재료, 복잡한 구조형태나, 지지조건, 다양한 결합부의 동적 특성을 정의하여 해석적으로 정확히 해결하기에는 어려움이 있다. 이러 한 제한조건을 손쉽게 해결하는 방법은 실 구조물에 대한 동적실험(dynamic test)을 통하여 단기간에 동적특성을 결정하고 SDM(structure dynamic modification)이나 FRS(force response simulation)를 수행하여 임의의 좌표 공간에 대한 진동수준을 해석적으로 예측할 뿐만 아니라 구조물의 진동제어 를 위한 동적인자를 변경시킬 수 있는 정보를 제공하며 장비를 방진할 경우 신뢰성 있는 전달률을 결정할 수 있다. 실험적으로 철교, 교량이나 건물의 철골구조 및 2층 바닥 등 대,중형의 복잡한 구조물에 대항 동특성을 나타내 는 모빌리티를 결정할 경우 충격 가진 실험이 사용되는 실험장비 측면에서 나 실험을 수행하는 과정이 대체적으로 간편하다. 그러나 이 경우 대상 구조 물을 충분히 가진시킬수 있는 용량의 대형 충격기(large impact hammer)가 필요하게 된다. 이러한 동적실험은 약 길이 61m, 폭 16m의 4경간 교량에 대 하여 동적실험을 수행하여 가능성을 확인하였다. 여기서는 실험실 수준의 평 판모델을 제작하고 실제 현장에서 이루어질 수 있는 진동제어 구조물에 대 한 동적실험 및 FRS를 수행하는 과정과 동일하게 따름으로써 실제 발생할 수 있는 오차나 error를 실험실내의 차원에서 파악하여 진동원을 있는 구조 물에 대한 진동제어기술을 보유하고자 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.59-64
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• 1992

터빈 블레이드와 같이 회전하는 구조물의 파단은 공진 근처에서 진동이 발 생할 때에 이에 기인하는 피로에 의하여 발생한다. 그러므로 이와 같은 파단 을 피하기 위해서는 설계 단계에서 이론적인 계산에 의하여 구조물의 고유 진동수를 결정하는 것이 상당히 중요하다. 판이 회전을 받게 되면 원심력에 의하여 판의 강성이 증가하므로 고유진동수가 회전하지 않는 판의 고유진동 수보다는 상당히 증가하게 된다. 이에 대한 연구가 국내외에서 상당수 행하 여졌지만, 연구의 대부분이 회전의 영향을 고려하지 않은 정지판(stationary plate)에 대한 것이며 뢰전을 고려한 연구는 극히 제한되어 있다. 또한 회전 의 영향을 고려한 연구의 대부분이 해석 대상을 보로서 단순화 시켰고 해법 으로는 유한요소법과 Ritz법 등을 사용하였다. 이는 블레이드가 지니고 있는 기하학적인 형상과 진동 특성이 해석적인 방법으로 해결하는 데에는 상당한 어려움이 있기 때문이다. 실제적으로는 터빈 블레이드와 같은 회전체의 진동 특성이 설치각이나 비틀림각, 판의 형상비, 회전속도 등의 변화에 의하여 영 향을 받기 때문에 보와 같은 진동 거동을 보이기보다는 판이나 셀과 같은 진동 거동을 보이므로 보다 정확한 해석을 수행하기 위해서는 해석 대상을 판이나 셀로서 취급하는 것이 타당하다. 따라서 본 연구에서는 위와 같은 이 유 때문에 해석 대상을 등방성 사각판과 직교이방성 복합재료 사각판으로 선택하였으며, 구조물의 고유진동수에 영향을 미치는 다음과 같은 인자들을 해석에 고려하였다. 1. 회전속도 (rotational speed) 2. 설치각 (setting angle) 3. 허브의 반경 (hub radius) 4. 판의 형상비 (aspect ratio) 5. 적층순서 (stacking sequence)구조물에 대한 동적실험(dynamic test)을 통하여 단기간에 동적특성을 결정하고 SDM(structure dynamic modification)이나 FRS(force response simulation)를 수행하여 임의의 좌표 공간에 대한 진동수준을 해석적으로 예측할 뿐만 아니라 구조물의 진동제어 를 위한 동적인자를 변경시킬 수 있는 정보를 제공하며 장비를 방진할 경우 신뢰성 있는 전달률을 결정할 수 있다. 실험적으로 철교, 교량이나 건물의 철골구조 및 2층 바닥 등 대,중형의 복잡한 구조물에 대항 동특성을 나타내 는 모빌리티를 결정할 경우 충격 가진 실험이 사용되는 실험장비 측면에서 나 실험을 수행하는 과정이 대체적으로 간편하다. 그러나 이 경우 대상 구조 물을 충분히 가진시킬수 있는 용량의 대형 충격기(large impact hammer)가 필요하게 된다. 이러한 동적실험은 약 길이 61m, 폭 16m의 4경간 교량에 대 하여 동적실험을 수행하여 가능성을 확인하였다. 여기서는 실험실 수준의 평 판모델을 제작하고 실제 현장에서 이루어질 수 있는 진동제어 구조물에 대 한 동적실험 및 FRS를 수행하는 과정과 동일하게 따름으로써 실제 발생할 수 있는 오차나 error를 실험실내의 차원에서 파악하여 진동원을 있는 구조 물에 대한 진동제어기술을 보유하고자 한다. 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile whereas relaxivity at high field is not affected by τS. On the other hand, the change in τV does not affect low field profile but stron

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6977-6984
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• 2015

It is faced with the necessity of multi roll forming process of the ball slide rail which is made by adding the separate manufacturing processes, piercing, bending, trimming, to the roll forming process of a continuous plastic deformation, to improve the quality. However, the vibration and noise of the press machine in this process leads to the quality degradation of slide rail manufactured in this process. In this study, the roll was designed considering the optimal strain rates by the roll forming program with finite element method. And to estimate the static stability of the multi process the Von-Mises stress and deformation on the press was calculated with a structural analysis program. Also, to avoid driving systems in the resonance region their natural frequencies in the 1st and 2nd mode were calculated through the modal analysis. To verify its dynamic stability improvement the magnitudes of noise and vibration in the existing and studied system were compared using a microphone and accelerometers. And the widths and surface roughnesses of the rails which had been produced in the existing and studied process were measured. Therefore, it is known that multi roll forming process is stable in the analytical and experimental study.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.557-563
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• 2009

This study is on the properties of inorganic porous calcium silicate material made from silica powder through the autoclaving curing, the results of this study should be utilized fundamental data for the development of noise reduction porous solid material using siliceous byproduct generated by various manufacture process. For the manufacture of autoclave curing specimen, various calcareous materials used and siliceous materials used silica powder. In this study, properties in density and compressive strength according to the change of W/B and C/S ratio, microscopy for the shape of pore, SEM and XRD for the examination of hydrate after autoclave curing are carried out respectively. The test results shown that the more slurry density decrease, the more W/B increase at the fresh state, this tendency shown similar to in hardened state. Among the specimens of C/S ratio, the compressive strength of C/S ratio of 0.85 gave the highest the compressive strength. In the results of XRD, tobermorite generated by autoclaving curing was created all of specimens regardless of C/S ratio. To ascertain pore structure, we compared with existing porous calcium silicate product(ALC, organic sound absorbing porous material). The results of microscope observation, pore structure of specimen of this study was similar to that of existing inorganic sound absorbing foam concrete. therefore, we could conformed a possibility of sound absorbing porous solid material on the basis of the results.

• Science of Emotion and Sensibility
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• v.6 no.4
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• pp.41-49
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• 2003

To inspect how the different sensitivities in BAS(or BIS) modulate on the HRV pattern stimulated by positive or negative affective sound, we measured the electrocardiogram(ECG) of 25 students(male : 14), consisted of 4 groups depending on the BAS(or BIS) sensitivity, during listening meditation music or being exposed to noise. The power spectral density(PSD) of HRV was derived from the ECG, and the power of HRV was calculated for 3 major frequency ranges(low frequency[LF], medium frequency[MF], and high frequency[HF]). We found that the index of MF/(LF+HF), during listening music, was higher significantly in the individuals with a low BIS but high BAS than in the individuals with a low sensitivity in both BIS and BAS. Especially in the former group, there was a tendency that the index was higher during listening music than during being exposed to noise. For individuals with a high BIS, regardless of the BAS sensitivity, the difference of this index values was not significant. From these results we suggest that individuals with a low BIS but high BAS are more sensitive to positive affective stimuli than other groups, and the index of MF/(LF+HF) is applicable to evaluate positive and negative affects.

• Journal of KSNVE
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• v.6 no.1
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• pp.107-114
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• 1996

The damping characteristics of a cylindrical structure containing oil and bearing balls is investigated for external bending forces. The experimental data obtained through the use of bearing balls with viscous oil in a column is given and analyzed. The viscous action of the oil and inertia effects of the balls on the inside of column create a drag force. The drag force dampens the vibration of the column. This study aims to search for an optimum combination of oil and balls which would produce maximum damping. Machining oils of various viscosities along with ball bearings of various sizes place inside cantilevered aluminium tubes of various diameters to create a rig on which the damping properties of the oil and balls can be studied. The contileved tubes are studied in both horizontal and vertical positions in order to gauge the effect of gravity on the system. The actions of the ball in the column and damping characteristics are investigated according to the dimensionless terms. The Buckingham theorem is used to reduce the variables and to predict the damping of an oil ball column. Though the damping ratio remains fairly constant in the horizontal position of column, the damping ratio begins to increase as the ratio of the number of balls and column length rise above 0.28 in the vertical position of oil ball column. The ratio of the ball diameter to column diameter influences the damping ratio with an optimum diameter ratio. Slenderness ratio and gravity effects on the damping ratio ane investigated.

• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.5-12
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• 2015

Since blasting noise is impact noise, it will give a sudden shock to the human. In the case, such as the blast vibration, it has given aging buildings and livestock great damage to move the vibration along ground in nearby regions. In this study, the influence of the blasting generated during excavation was analyzed for effects on regional. A couple of field and laboratory surveys about geological were carried out to figure out the geological ratio in the study-performed area. Blast vibration noise was compared to the domestic and abroad case studies and each of the institutions permissible standards established the most appropriate criteria in site condition. The vibration velocity of blasting vibration exploits the values which were measured from test blasting on the ground in order to examine blasting effect. Considering the blasting point as the shortest distance from safety facilities (farms, private houses, etc.), the examination of the influence range, which was derived from the vibration velocity of blasting vibration, was performed to figure out how the point affected the safety facilities. Three-dimensional numerical analysis was performed a time history analysis in order to analyze the behavior of the structure for a dynamic blast load, which was determined in three directions of the blast vibration value. The results of three-dimensional numerical analysis and the blasting effect of blasting vibration estimation equation blasting vibration of impact circle with accompanying test blasting were compared. And the analysis confirmed similar results figures.

• 재활복지
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• v.20 no.4
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• pp.247-264
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• 2016

The Children's Home Inventory for Listening Difficulties (CHILD) questionnaire has been applied for assessing listening and communication difficulties in various home situations for children with hearing loss. The purpose of the study was to translate the CHILD questionnaire for parents into Korean and verify reliability and validity of Korean version of CHILD (CHILD-K). CHILD-K was completed by 55 parents of children (from ages 3~12 years) using cochlear implants (CI). Among the 55 children, 27 were in preschool and 28 in elementary. Internal consistency reliability of CHILD-K was verified by Chronbach's alpha. The mixed factorial ANOVA was conducted to compare the effects of the age group and situation factors (Quiet, Noise, Distance, Social, and Media factors) on the score of CHILD. The results indicated that CHILD-K showed excellent internal consistency reliability (${\alpha}=.96$). The CHILD scores among age groups were significantly different as the older age group resulted in higher scores in all situations except Distance. For both groups the mean scores for the Quiet situation were significantly higher than other situations, and the mean scores for the Social situation were significantly lower than other situations. Moreover, analysis showed that children with CI had difficulties in the Social situation combined with other situation factors. The results indicate that the Korean version of CHILD questionnaire is a reliable tool for the assessment of communication abilities in home situation in Korean-speaking children using CI.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.252-260
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• 2021

For frailty management, the importance of resistance exercise has been emphasized, and various devices have been developed. Recently, digital weight control technology that converts electromagnetic resistance to a digital weight is attracting attention, but there are no reports confirming the effectiveness and safety of the device for seniors in Korea. This study conducted a biomechanic-based ergonomic analysis of an elderly-friendly exercise device utilized in digital load control technology to suggest a direction for development. Twenty seniors (age: 62.40 ± 2.09 years) were included. The load of the device was classified into three levels, and the muscle activity and heart rate were assessed during three experimental motions. A questionnaire based on the International Organization for Standardization 9241-11 was adopted to evaluate the stability, operationality, efficiency, and satisfaction with the software and device. The program could be divided into three exercise intensities that can be utilized in the field depending on whether the exercise load, muscle activity, and heart rate were consistent. The monitor size needed to be enlarged to make the menu Korean, reduce the device size, and minimize noise. Considering these findings, the development of an advanced age-friendly exercise device by improving the size, display, and noise is suggested.

• Journal of Sasang Constitutional Medicine
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• v.10 no.1
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• pp.81-99
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• 1998

1. Background : Sasang Constitutional Medicine divides mankind into Taeyangin(太陽人), Taeumin(太陰人), Soyangin(少陽人) and Soeumin(少陰人) according to appearance, moral nature and characteristic of constitutional symptoms, and it is a medical science to study about different treatment for each constitution. In Sasang Constitutional Medicine, diagnosis of constitution was so important that we had the necessity of studying constitutional diagnostic method which had presented wholly and intuitively in Dongyi Soose Bowon(東醫壽世保元) with objective and analytic thinking. There were several attempts to classify Sasang Constitutional Types through morphological investigation of each parts of body. The one of them was to use measuring the body. In this study, we purposed to make clear whether the analysis of fingerprints and palm, one of the physical anthropologic methods would be helpful to classify Sasang Constitution. 2. Method : After practicing Questionnaire I and QSCC(Questionnaire of Sasang Constitution) II from 347 healthy Korean adults(242 males and 106 females), we analyzed fingerprints and palm prints of 208 people(142 males and 66 females) who were classified same constitution from two questionnaires. We analyzed the types of fingerprints according to the number of triradius and counted the number of dermal ridges from fingerprint center to triradius. We found triradius in the lower part of each finger and analyzed the courses of dermal ridges and counted the number of dermal ridges between each triradius. We mesured angle atd, and then researched relationship between fingerprints, palm prints and Sasang Constitution. 3. Result and Conclusion : The results of Sasang Constitution analysis of 208 Korean adults showed 76 Taeumin(36.5%), 81 Soeumin(39.0%) and 51 Soyangin(24.5%). The analytic results of fingerprints and palm prints are as follows : The types of fingerprints were helpful to sort Taeumin and the types of palm prints were helpful to sort Soyangin and Soeumin especially. In addition, the number of dermal ridges in fingerprints and palm prints were helpful to sort Soyangin. Fingerprints and palm prints have characteristic in each constitutions, so the investigation of fingerprints and palm prints seems to helpful to classify Sasang Constitution. We are planning to report fingerprints and palm prints of more subjects.