• Journal of Nutrition and Health
• /
• 제24권1호
• /
• pp.30-39
• /
• 1991

This study was designed to investigate the effects of dietary calcium. serum estrogen level and physical activity on the bone status of 116 healthy elderly women living in urban area. Current calcium intake was assessed by convenient method(refered to as Ca intake) and calcium containing food frequency method(refered to as Ca index) Daily activity record was used for the estimation of physical activity level, and serum estrogen level was measured from fasting blood of subjects. The rate of bone resorption was evaluated by the determination of hydroxyproline(Hpr) in fasting urine with correction for creatinine excretion. The results of this study are summarized as follows : 1) Average daily Ca intake of subjects was 621.4$\pm$155.8mg, which is above the Korean recommended dietary allowances. However 44.8% of the subjects consumed Ca below RDA level. Ca index score was significantly correlated with the bone status(P<0.05), Ca intake did not show significant correlation with the bone status although a positive trend of influence was evident. 2) Average serum estrogen level of subjects was 18.7$\pm$9.8pg Contrary to our anticipation. estrogen level did not show any significant relation to age and bone status. 3) Daily physical activity was classified into four categories by activity intensity : sedentary. moderate, active and severe. The average physical activity of subjects belong to moderate level. and the bone status was significantly related to the physical activity(P<0.01) 4) Among other influential factors such as age, pocket-money. family type. drinking, smoking and BMI, there was a significant difference between bone status and BMI(P<0.05). 5) Multiple regression analysis of variables showed that physical activity has greater effect than other variables when the entire subjects were taken into account. However. eliminating the subjects whose bone status rated as excellent(Hpr/cr<0.009), Ca index showed higher correlation than physical activity. These results have demonstrated that dietary calcium intake is the primary important factor for keeping good bone health and that bone status of subjects with a sufficient calcium intake is affected by various factors such as physical activity, age, smoking. BMI and others.

• 한국생활과학회지
• /
• 제10권1호
• /
• pp.113-126
• /
• 2001

The purpose of this study was to investigate clothing behavior and ornaments wear of university students. The subject of this study consists of 241 college students who were attended in Kongju National University. SPSSWIN Program was utilized to calculated frequency(N), mean value(M) and standard deviation(SD) for statistical analysis. Differences among the populations were examined through T-test, F-test, $x^2$-test. The results of this study were as follow : 1. Clothing behavior of university students had significant difference according to sex, grade. In general, female students showed higher score than did male students in clothing interest, clothing conformity, self-estimation about clothing, clothing dependence, clothing aesthetic, clothing modesty, A first-year students had high tendency in clothing interest. 2. The wear of ornaments had significant difference according to variables. Buying the ornaments, most of students sot information in show window and emphasized on design. Male students wanted to have the ornaments of shoes, watch, hat & necklet, but female students wanted to have the ornaments of shoes, earring, necklet & hairpin. 3. Clothing behavior has Influenced university students' ornaments wear. The university students who appeared to be interested in clothes were apparently influenced by peers when selecting ornaments. Ornaments were usually bought in the department store, while belts were among the most popular choices. Students who stressed color when purchasing ornaments showed a high level of interest in and dependence on clothes. On the basic of these results, we can conclude that university students' taste in clothing behavior and use of ornaments wear depend on several different factors. Therefore, it is possible to outline the shift in clothing attitudes during adolescence. In order to understand university students' behaviour concerning clothes, much guidance and various studies on the subject are much recommended.

• Journal of Communications and Networks
• /
• 제18권5호
• /
• pp.837-845
• /
• 2016

Providing a customer with tailored location-based services (LBSs) is a fundamental problem. For location-estimation techniques with radio-based measurements, LBS applications are widely available for mobile devices (MDs), such as smartphones, enabling users to run multi-task applications. LBS information not only enables obtaining the current location of an MD but also provides real-time push-pull communication service. For indoor environments, localization technologies based on radio frequency (RF) pattern-matching approaches are accurate and commonly used. However, to survey radio information for pattern-matching approaches, a considerable amount of time and work is spent in indoor environments. Consequently, in order to reduce the system-deployment cost and computing complexity, this article proposes an indoor positioning approach, which involves using Asus Xtion to facilitate capturing RF signals during an offline site survey. The depth information obtained using Asus Xtion is utilized to estimate the locations and predict the received signal strength (RF information) at uncertain locations. The proposed approach effectively reduces not only the time and work costs but also the computing complexity involved in determining the orientation and RF during the online positioning phase by estimating the user's location by using a smartphone. The experimental results demonstrated that more than 78% of time was saved, and the number of samples acquired using the proposed method during the offline phase was twice as much as that acquired using the conventional method. For the online phase, the location estimates have error distances of less than 2.67 m. Therefore, the proposed approach is beneficial for use in various LBS applications.

• Journal of Power Electronics
• /
• 제16권4호
• /
• pp.1324-1335
• /
• 2016

This article explores the speed regulation problem of permanent magnet synchronous motor (PMSM) systems subjected to unknown time-varying disturbances. A continuous sliding mode control (CSMC) technique is introduced for the speed loop to enhance the robustness of PMSM systems and eliminate the chattering phenomenon caused by high-frequency switch function in the conventional control law. However, the high control gain of the CSMC law in the presence of strong disturbances leads to large steady-state speed fluctuations for PMSM systems. In many application fields, PMSM systems are affected by time-varying disturbances instead of constant disturbances. For example, electric bicycles are usually affected by changing environmental disturbances, including wind speeds, road conditions, etc. These disturbances may be in the form of constant, ramp, and parabolic disturbances. Hence, a generalized proportional integral (GPI) observer is employed to estimate these types of disturbances. Then, the disturbance estimation method and the aforementioned CSMC method are combined to establish a composite sliding mode control method called the CSMC+GPI method for the speed loop of PMSM systems. Contrary to the conventional sliding mode control technique, the proposed method completely eliminates the chattering phenomenon caused by the switching function in the conventional control law. Moreover, a small control gain for the CSMC+GPI method is chosen by feed-forwarding estimated values to the speed controller. Hence, the steady-state speed fluctuations are small. The effectiveness of the proposed control scheme is verified by simulation and experimental result.

• 정보과학회 논문지
• /
• 제42권6호
• /
• pp.707-712
• /
• 2015

모바일 클라우드 컴퓨팅은 모바일 기기의 자원제약적인 한계를 극복하기 위해 클라우드 서비스를 활용하는 기술로 모바일 기기에서 실행해야 할 일부 작업을 클라우드에서 수행하게 하는 컴퓨테이션 오프로딩 기법이 사용된다. 오프로딩에 필요한 통신 비용보다 모바일 기기 내에서의 연산 비용이 클 경우 모바일 기기는 클라우드에게 작업 수행을 위탁한다. 모바일 기기에서 수행할 작업과 클라우드에서 수행할 작업을 분할하기 위한 기존의 비용 분석 모델은 함수 호출에 필요한 데이터 전송과 응답 시간만을 오프로딩 비용으로 산정하였다. 본 논문에서는 컴퓨테이션 오프로딩 비용 산출 시 함수의 호출 및 응용 프로그램의 동기화 빈도를 고려한 작업 분할 기법을 제안하였고 실험을 통해 기존의 기법들에 비해 에너지 효율성을 높일 수 있음을 확인하였다.

• 한국도로학회논문집
• /
• 제18권4호
• /
• pp.55-61
• /
• 2016

PURPOSES : The objective of this study was to determine the relationship between the dielectric characteristics of asphalt mixtures and the air voids present in them using ground penetrating radar (GPR) testing. METHODS : To measure the dielectric properties of the asphalt mixtures, the reflection coefficient method and the approach based on the actual thickness of the asphalt layer were used. An air-couple-type GPR antenna with a center frequency of 1 GHz was used to measure the time for reflection from the asphalt/base layer interface. A piece of aluminum foil was placed at the interface to be able to determine the reflection time of the GPR signal with accuracy. An asphalt pavement testbed was constructed, and asphalt mixtures with different compaction numbers were tested. After the GPR tests, the asphalt samples were cored and their thicknesses and number of air voids were measured in the laboratory. RESULTS : It was found the dielectric constant of asphalt mixtures tends to decrease with an increase in the number of air voids. The dielectric constant values estimated from the reflection coefficient method exhibited a slight correlation to the number of air voids. However, the dielectric constant values measured using the approach based on the actual asphalt layer thickness were closely related to the asphalt mixture density. Based on these results, a regression equation to determine the number of air voids in asphalt mixtures using the GPR test method was proposed. CONCLUSIONS : It was concluded that the number of air voids in an asphalt mixture can be calculated based on the dielectric constant of the mixture as determined by GPR testing. It was also found that the number of air voids was exponentially related to the dielectric constant, with the coefficient of determination, $R^2$, being 0.74. These results suggest that the dielectric constant as determined by GPR testing can be used to improve the construction quality and maintenance of asphalt pavements.

• 한국도로학회논문집
• /
• 제16권5호
• /
• pp.59-66
• /
• 2014

PURPOSES : This study is to predict the Sound Pressure Level(SPL) obtained from the Noble Close ProXimity(NCPX) method by using the Extended Kalman Filter Algorithm employing the taylor series and Linear Regression Analysis based on the least square method. The objective of utilizing EKF Algorithm is to consider stochastically the effect of error because the Regression analysis is not the method for the statical approach. METHODS : For measuring the friction noise between the surface and vehicle's tire, NCPX method was used. With NCPX method, SPL can be obtained using the frequency analysis such as Discrete Fourier Transform(DFT), Fast Fourier Transform(FFT) and Constant Percentage Bandwidth(CPB) Analysis. In this research, CPB analysis was only conducted for deriving A-weighted SPL from the sound power level in terms of frequencies. EKF Algorithm and Regression analysis were performed for estimating the SPL regarding the vehicle velocities. RESULTS : The study has shown that the results related to the coefficient of determination and RMSE from EKF Algorithm have been improved by comparing to Regression analysis. CONCLUSIONS : The more the vehicle is fast, the more the SPL must be high. But in the results of EKF Algorithm, SPLs are irregular. The reason of that is the EKF algorithm can be reflected by the error covariance from the measurements.

• 대한토목학회논문집
• /
• 제31권2C호
• /
• pp.83-92
• /
• 2011

암반에서의 탄성계수는 암반의 변형특성을 나타내는 매우 중요한 인자로서 암반에서의 터널굴착으로 인한 내공변위를 파악하는데 이용된다. 그럼에도 불구하고 현재까지는 암석종류 및 절리특성을 반영하여 탄성계수를 산정하는 연구는 미흡한 것으로 판단된다. 따라서, 본 연구는 다양한 암석 및 절리상태에서 암반의 탄성계수를 추정하는 방법과 그 결과를 제시하고자 한다. 이를 위해서 2차원 개별요소법에 근거한 수치해석이 수행될 것이며 이를 통해 암석과 절리상태가 고려된 터널굴착 유발 내공변위가 조사될 것이다. 조사된 변위결과는 암반에서의 원형터널에 대한 탄성이론을 역이용하여 암석종류 및 절리특성이 반영된 탄성계수를 추정하는데 사용될 것이다. 본 연구를 통해 암석종류 및 절리특성을 고려하여 추정된 탄성계수는 향후 실무에서 절리가 형성된 암반터널에서의 발생변위를 파악함에 있어서 그 활용도가 매우 클 것으로 기대된다.

• 한국실내디자인학회논문집
• /
• 제24권6호
• /
• pp.145-153
• /
• 2015

For this research with the objects of spaces in two department stores which can be referred to as representative facility of commercial space, observation test has carried out to estimate how much visitors rivet their eyes to the display of shops. In addition, to find out what effect the difference among the department types has on the selective attention to space element, the observation time was applied as a medium for estimation. The followings are the result from analyzing the observation frequency and the observation intensity feature of each section where the characteristics of design could be found at attention. First, both images of A and B had concentrative dominant-observation at left shops. In case of Image A, Customers began to observe the right shops very attentively after 25 seconds, and with Image B, the attentive observation at right and left took place alternatively after 35 seconds. In other words, regardless of the characteristics of shop displays, the left shops were observed first while in case of the observation after the early and middle time-frame the characteristics of shops were found to have effects on observation. Second, the normal observation showed some difference among attention sections over time while on the whole both images of A and B had the same highly attentive observation at the middle space. Accordingly, it could be concluded that the middle space was playing a faithful role as background for commercial spaces. Third, the ignorant observation, which is the opposite to the attentive observation, was found different between the images of A and B. When the ignorant observation is considered to have intentionality, it will be possible to set up the display which may attract the attention aggressively by the process of figuring out the characteristics of ignored shops.

• 비파괴검사학회지
• /
• 제21권2호
• /
• pp.152-162
• /
• 2001

비파괴 평가 기술들 중의 하나인 레이저 초음파 응용 기술은 각종 구조물에 존재하는 표면결함에 의한 신호를 통해 건전성을 평가하는 기법이다. 따라서 결함의 신뢰성 높은 정량적 평가를 위해서는 결함으로부터의 레이저 초음파 신호특성에 대한 기본적 이해가 필수적이며 따라서 이를 위한 신호해석 연구가 요구된다. 본 연구에서는 레이저유도 초음파에 의한 one-sided 기법을 이용하여 표면균열을 평가하고자 하였다. 하지만 레이저를 이용한 평가방법들은 수신된 신호의 해석이 까다로우며 또한 상당한 전문적인 지식이 요구된다. 웨이블렛 변환(wavelet transform, WT) 기법은 신호처리 분야에서 하나의 새로운 방법으로서 다양한 분야에 적용되고 있으며 특히 한 시점에 대한 주파수 분해가 가능한 신호처리 방법으로서 시간-주파수 분석에 아주 유용하게 이용되고 있다. 본 연구에서는 이러한 레이저 유도 초음파를 이용하여 재료의 표면 결함신호들에 대한 웨이블렛 변환기법을 적용하여 보다 정량적인 결함 크기를 예측하고 그 타당성을 평가하고자 하였다.