• 대한근관절건강학회:학술대회논문집
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• 2002.11a
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• pp.238-246
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• 2002

최근 경제의 발전과 의학의 발달로 인하여 인간의 수명은 점차 연장됨에 따라, 노인인구도 급격히 증가하고 있다. 40세 이상 여성 인구도 8.998천명으로 전체 여성의 38%를 차지하며 이는 매년 증가할 것이다. 그리하여 전체 인구에 대한 폐경 여성의 점유율도 급격히 증가하고 있다. 폐경 이후 $5{\sim}10$년 동안 매년 $2{\sim}4%$씩 골농도가 감소하고 있기 때문에 폐경기 여성을 위협하는 주요 질환 중 하나가 골다공증이다. 하지만 골다공증은 뚜렷한 자각증상이 없어 골 기형 및 골절이 발생하기 전에는 조기발견이 어렵다. 골다공증은 모든 중년 여성의 건강문제이므로 지역사회에서 골절 발생 위험율을 줄일 수 있도록 골다공증 예방을 위한 건강관리가 필요하다. 본 연구의 목적은 지역사회에서 적용할 수 있는 골다공증 예방 프로그램을 개발하여 그 효과를 검정한 후 지역사회 중년 여성 건강증진 프로그램으로 활용코저 함에 있다. 골다공증 예방 프로그램은 운동과 교육으로 구성하였으며, 12주 동안 점핑 동작 위주의 에어로빅과 스텝퍼 운동과 근력강화운동(최대 심박수의 $70%{\sim}80%$, $70{\sim}80$분, 3회/주)을 병행하여 실시하였고, 교육은 운동과 칼슘 섭취의 중요성을 건강 신념 이론에 근거하여 자기 효능감을 증대시키는 교육을 하여 지속적인 운동 실천과 칼슘식이 섭취를 하도록 하였다. 대상자는 서울시 일개 보건소에서 골감소증으로 진단받은 폐경 여성으로 실험군 19명과 대조군 19명이었다. 골다공증 예방 프로그램의 효과는 골밀도, DPD ratio, osteocalcin, 일일 평균 칼슘섭취량, 일일 열량 소모량, 배근력, 최대 산소 섭취량, 제지방량과 건강신념 변수로 측정하였다. 수집된 자료는 PC SPSS 8.0 프로그램을 이용하여 대상자의 일반적 특성은 실수와 백분율로 실험군과 대조군의 동질성 검사는 t-test, $x^2-test$ 및 Fisher exact test를 이용하였고, 두 집단 간 결과변수들의 중재 전후의 차이는 t-test로 분석하였다. 연구 결과는 다음과 같다. 1) $L_{2-4}$ 골밀도는 실험군이 대조군에 비하여 유의하게 높았다. 2) DPD ratio와 osteocalcin은 두 집단간 유의한 차이가 없었다. 3) 배근력은 실험군에서 대조군보다 유의하게 증가하였으나, 제지방량과 최대 산소 섭취량은 유의한 차이가 없었다.

• The Korean Journal of Applied Statistics
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• v.26 no.6
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• pp.1033-1041
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• 2013

In this paper, we investigate several variance estimators for pps systematic sampling. Unfortunately, there is no unbiased variance estimators for a systematic sample because systematic sampling can be regarded as a random selection of one cluster. This study provides guidance on which variance estimator may be more appropriate than others in several circumstances. We judge the efficiency of variance estimators for systematic sampling based on of their relative biases and relative mean square error. Also, we investigate variance estimation problems for two-stage systematic sampling applied for the Food Raw Material Consumption Survey and the Establishment Labor Force Survey simulation study, in order to consider the popular two-stage pps systematic sample design for establishment and household survey in Korea.

• 대한공업교육학회지
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• v.31 no.1
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• pp.185-199
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• 2006

In this paper, to detect lateral direction sound pressure fiber optic sensor using Fabry-Perot interferometeric sensor array was fabricated and experimented. This parallel sensor array composed of one light source and the light split into each sensor using directional coupler and to see the output signal the array system do not need any digital signal processor. As a lateral direction sound source arbitrary sound frequency of 100Hz, 200Hz, and 655Hz using by nondirectional speaker were applied to the array sensor which installed on $60cm{\times}60cm{\times}60cm$ latticed structure. The detected signals from the two sensors were analyzed in the time and frequency domains. It was confirmed that the suggested sensor array detected applied sound source well but there were a little amplitude differences in between the sensors. Because the sensor supported simply at both ends theoretical analysis was performed and its solution was suggested. To compare the theoretical and experimental results arbitrary sound frequency of 2kHz was applied to the sensor array. It shows that experimental results was good agreement with theoretical results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.2
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• pp.142-152
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• 1992

This paper presentes a new method to measure high electric field (or high voltage) by using crystalline SiO2 which has very high half wave voltage. There are many difficulties in measuring high electric field using other crystals which have generally low half wave voltage.By applying Stokes parameter and Mueller matrix. We derive optical modulation equation in the sensor which is composed of a polarizer, and Mueller matrix, we derive optical modulation equation in the sensor which is composed of a polarizer, a Pokels material, and an analyzer, We theoretically analyzed electro-optic effect, and calculated the phase retardation and half wave volt age of the birefringent material. The designed optical valtage sensor has very excellent linearity up to 20KV without divided volt-age. The maximum error was measured within 3%. Before annealing of Sio2 crystal, the maximum variation of the output voltage is 7.5% with varying temperature from \ulcorner20˚c to 60˚c. But, after annealing of SiO2 crystal, the output voltage variation is improved within 1%error.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.101-109
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• 2017

This study aims to quantitatively analyze impacts of the team-based learning (TBL) method on learning of architectural engineering students. A TBL-based education program, consisted of preparation, readiness assurance, and application phases, was proposed by considering characteristics of architectural engineering education in South Korea and was applied in building construction classes. In order to measure learning effects and satisfaction levels of the proposed TBL-based education program, a set of questionnaires was conducted with students who took the building construction classes. As the results, learning effects and satisfaction levels of the TBL-based approach were higher than those of traditional approaches. Individual and team readiness assurance tests in the readiness assurance phase were the most effective and satisfactory items, while assessment in the application phase was the least effective and satisfactory item.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.965-973
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• 1992

Boilers, which are considered to be one of the basic equipment in industry, consume large potion of nation's petroleum and their demand is growing everyday. In recent, the technology improvement in production of high efficiency boilers and their effective utilization is needed for design of boiler which steam condition is the large capacity of high temperature and high pressure. It is necessary that boiler control system be studied for high efficiency, high reliability and smooth operation. The control of drum pressure and water level particularly becomes an important task for greater accuracy with the avail ability of boiler operation. To achieve this aim, dynamic analysis of a boiler is accomplished by choosing a boiler as a model. Transfer function thus obtained is made a comparison of measurement with reckoning to technical design data. The results of comparison makes it possible to verify thermodynamical analysis on the dynamic behavior of the overall system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.2
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• pp.249-258
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• 1998

In land mobile communication, very extensive studies on pilot symbol assisted modulation (PSAM) have been made on fading compensation. This paper analyzes the effect of power amplifier nonlinearity on PSA-QAM with maximal ratio combining space diversity. In practical PSAM, information on fading is obtained through interpolation of the pilot symbols. We employed the interpolation filter which could minimize the average power of error and analyzed effects on the system performance of the number of filter taps, period of the pilot symbol frame, and the Doppler frequency. Nonlinear power amplifiers of class AB, B, and C were incorporated in the system models and their AM/AM and AM/PM characteristics were taken into account in the performance analysis. We showed the performance variations according to the types of the nonlinear power amplifiers in the AWGN and Rayleigh fading channels using nonlinear compensation technique, Cartesian Feedback Loop (CFB).

• Journal of Navigation and Port Research
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• v.38 no.5
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• pp.503-509
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• 2014

In this study, a new concept perforated breakwater is proposed, which is having resonant channels. In the channel, perforated plate is installed for dissipating wave energy induced by flow separations. The breakwater has two advantages compared with conventional perforated breakwater having wave chamber with slotted walls. One is easy to control the target wave condition for dissipating wave energy, and the other is having the high structural safety because the structural members are not exposed to impact waves, directly. To evaluate wave reflection characteristics of the proposed breakwater, numerical experiment was carried out by using Galerkin's finite element model based on the linear potential theory. The results indicated that considerable energy dissipation occurs near the resonant period of channel, and wave reflection characteristics are affected by channel shape, location and opening ratio.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7831-7837
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• 2015

In order to understand how various support programs affect the development of traditional performing arts, I used descriptive statistics and multivariate statistics analysis on 267 surveys. I estimated relationship between item-whole by calculating mean and standard deviation. This will help us comprehend effects of the variables. Cronbach alpha coefficient, a measure of internal consistency, exceeded 0.7, indicating that reliability is satisfactory. I have established one main hypothesis and four sub-hypothesis to identify the relationship between support programs and the performing arts more clearly. The result supports that the support programs do have effects on the performing arts. However, there are not enough researches done on this subject, and additional researches are needed in order to systemize relevant theories and the development of performing arts industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5412-5419
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• 2011

The need is growing for high-speed spindle because various equipment are becoming more precise, miniaturization and high speed with the development of industries. Air-lubricated dynamic bearings are widely used in the optical lithographic manufacturing of wafers to realize nearly zero friction for the motion of the stage. Air-lubricated dynamic bearing can be used in high-speed, high-precision spindle system and hard disk drive(HDD) because of its advantages such as low frictional loss, low heat generation, averaging effect leading better running accuracy. In the paper, numerical analysis is undertaken to calculate the performance of air-lubricated dynamic bearing with herringbone groove. The static performances of herringbone groove bearings which can be used to support the thrust load are calculated. Electrochemical micro machining($EC{\mu}M$) which is non-contact ultra precision machining method has been developed to fabricate the air-lubricated dynamic bearing and optimum parameters which are inter electrode gap size, concentration of electrolyte, machining time are simulated using numerical analysis program.