• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.6
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• pp.712-720
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• 2016

The purpose of this study was to inspect ballistic match of copper bullet at 4 points by analyzing vertical deviation about shot group of the 5.56 mm common bullets and copper bullets. The 5.56 mm bullet with new copper core material was developed for mitigation of environmental pollution and harmfulness to human body. The results of this study are as follows; using the regression analysis, estimated reference value of ballistic match were 51.6 mm, 64.9 mm, 87.3 mm and 99.6 mm at 25 m, 100 m, 200 m and 250 m range respectively. When analyzing the shooting test data, alternative hypothesis(The vertical deviations are less than the reference value) was adopted as the result of analyzing data using t-test. And the values of data through tool(PRODAS) and standard trajectory equation meet requirements of estimated ballistic match respectively. In conclusion, the level of ballistic match of 5.56 mm copper bullets meets the estimated reference level through regression analysis at 4 points.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1127-1134
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• 2002

The present paper provides an engineering J estimation equation for surface cracked plates under combined bending and tension. The proposed equation is based on the reference stress approach, and the most relevant normalising loads to define the reference stress for accurate J estimations are given for surface cracked plates under combined bending and tension. Comparisons with J results from extensive 3-D FE analyses, covering a wide range of crack geometry, plate geometry and loading combination, show overall good agreement not only at the deepest point but also at arbitrary points along the crack front. for pure tension, agreement between the estimated J and the FE results is excellent, even at the surface point. On the other hand, for pure bending and combined bending and tension, the estimated J values become less accurate for locations close to the surface point. Thus the results in this paper will be useful to assess short-term fracture or low cycle fatigue of surface defects in plates under combined bending and tension.

• Clinical and Experimental Pediatrics
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• v.54 no.7
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• pp.287-291
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• 2011

Multiple psychosocial problems and many chronic diseases of adulthood can be influenced by adolescent nutritional problems. In Korea, adolescent obesity and obesity related health risks have been increased and insufficient intakes of nutrients, such as calcium, iron and potassium, and distorted thinking about obesity are also common. However there are no comprehensive countermeasure because of the excessive burden of studies and the lack of community interest. And the nutrition guidelines that is suitable for Korean adolescent leaves something to be desired, and the pediatrician's concern is lacking yet. In the Korean dietary reference intakes 2010 that was revised according to the 2007 Korean National Growth Chart and 2007 Korean National Health and Nutrition Examination Survey, the range for adolescents is changed to the age 12-18 and dietary reference intakes of some nutrients mainly with vitamin D is changed. Recently several researches, about how school nutrition policies and media effect on eating habits and the weight concerns, and influences of public nutrition policies and fast food commercials have been actively studied to improve adolescent nutritive conditions. In this review, I summarize the dietary reference intakes for Korean adolescents that were revised in 2010, and current studies about the adolescent nutrition.

• Journal of Biomedical Engineering Research
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• v.39 no.2
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• pp.80-86
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• 2018

The aim of this study were to establish the clinical references and guidelines for the maximum standardized uptake ($SUV_{max}$) value of pancreatic cancer, pancreatitis, and normal pancreas in $^{18}F-FDG$ PET-CT examinations for pancreatic disease. For this purpose, we performed the statistical analysis on the descriptive statistics, percentiles and inter quartiles range (IQR), normal distribution, and using the probability density function for pancreatic cancer, pancreatitis, and normal pancreas. As a result, the clinical reference of $SUV_{max}$ for the pancreatic cancer, pancreatitis, and normal pancreas was more than 3.45, 1.91 to 2.62, and less than 1.91, respectively. Also, optimal cut-off value for applying the dual time point PET-CT examination was determined to be 2.62. The results of this study are summarized as follows: first, we suggests the clinical reference and guideline for the pancreatic cancer, pancreatitis, and normal pancreas, and second, suggests a scientific approach to improve diagnostic accuracy of pancreatic disease by deviating from an approximate experience approach.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.741-747
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• 2001

Three-dimensional, elastic-plastic finite element analyses for circumferential through-wall cracked pipes are performed using actual tensile data of stainless steels, for two purposes. The first one is to validate the recently-proposed enhanced reference stress (ERS) method to estimate the J-integral and COD for circumferential through-wall cracked pipes. The second one is to compare those results with the GE/EPRI estimations. It is found that the J-integral and COD estimations according to the GE/EPRI method can be very sensitive to how the stress-strain data are fitted using the Ramberg-Osgood relation. Moreover, no tendency can be found regarding the most appropriate fitting range for the Ramberg-Osgood fit. On the contrary, the J-integral and COD estimations based on the ERS method give more accurate results than the GE/EPRI estimation. The present results provide confidence in applying the proposed method to the Leak-Before-Break(LBB) analysis.

• Journal of The Korean Astronomical Society
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• v.22 no.1
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• pp.63-79
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• 1989

Current estimates, based on the same star-count analysis, of the distance to the globule Bamard 361 range from 300 pc to 650 pc. All the problems associated with the estimates have been fully rectified in this study, and a modification has been made to the classical Wolf diagram to improve the accuracy in the distance determination. A reference field was carefully selected close to the globule but well outside the globule boundary, and star counts for this field were performed on the blue POSS plate in order to set up the reference magnitude sequence appropriate to the general area of B 361. From the reference sequence, the stellar density function has been derived specifically for the direction toward the globule. Correction was made for the general interstellar extinction, and the luminosity function with the Wielen's dip was adopted. The resulting density function clearly reveals the existence of the local Cygnus-Orion arm in the direction of B 361 at about 700 pc away from the Sun. Analysis of the star-count data for the program field locates the globule at distance $600{\pm}50$ pc ; thus, the globule is an object located in the Cygnus-Orion arm, residing somewhat toward its leading edge.

• Journal of Families and Better Life
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• v.9 no.1 s.17
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• pp.145-160
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• 1991

The purpose of this study is to suggest some fundamental data for the welfare of consumers by investigation some characteristics of the housewives and their attitudes toward a famous brand. For the purpose of this study, the samples were distributed to houswives who lived in Seoul. The 493 data obtained were analyzed by frequency distribution, percentile, $X^2$-test, t-test, F-test, Pearson's correlation, Duncan's multiple range test and Stepwise multiple regression analysis. The major finding were follows ; The major finding were follows ; 1) In general the score for the brand preference of the housewives was somewhat high. There were significant differences between the brand preference of the housewives and the socio-demographic, reference group variables. 2) There were significant differences between the brand image of housewives and the socio-demographic, reference group variables 3) In general the score for the dissatisfaction of the housewives was somewhat low. There were significant differences between the dissatisfaction the housewives and the socio-demographic variables. 4) The brand preference of the housewives had a positive relationship with the level of their dissatisfaction. 5) The most influential variables for the brand preference of the housewives was in the rank of reference group, income, education level.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.33-36
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• 2001

Torque ripple control of brush less DC motor has been the main issue of the servo drive systems in which the speed fluctuation, vibration and acoustic noise should be minimized. Most methods for suppressing the torque ripples require Fourier series analysis and either the iterative or least mean square minimization. In this paper, the novel approach to achieve the ripple-tree torque control with maximum efficiency based on the d-q-0 reference frame is presented. The proposed method optimize the reference phase current waveforms including even the case of 3 phase unbalanced condition, and the motor winding currents are controlled to follow up the optimized current waveforms by delta modulation technique. As a result, the proposed approach provides a simple and clear way to obtain the optimal motor excitation currents. The validity and practical applications of the proposed control scheme are verified through the simulations and experimental results.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.365-372
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• 1995

A signal processing technique for interferometric fiber-optic sensors is proposed. It does not require a any special optic components such as phase modulator, $3times3$ couplers,to obtain the full sensitivity of the interferometer. Instead, it requires a reference interferometer for phase referencing and a reference mirror for intensity referencing, but intensity referencing can be done without using the r reference mirror. The new technique utilizes the frequency chirping of the laser diode to process t the sensor signal with both wide dynamic range and high sensitivity of the interferometer. It was a applied to an internal-mirrored FP interferometric temperature sensor to obtain the system noise of $4\times10^{-3\circ}C$ from I cm FP Interferometor sensor device.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.528-533
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• 2016

A low voltage high PSRR CMOS Bandgap circuit capable of generating a stable voltage of less than 1 V (0.8 V and 0.5 V) robust to Process, Voltage and Temperature (PVT) variations is proposed. The high PSRR of the circuit is guaranteed by a low-voltage current mode regulator at the central aspect of the bandgap circuitry, which isolates the bandgap voltage from power supply variations and noise. The isolating current mirrors create an internal regulated voltage $V_{reg}$ for the BG core and Op-Amp rather than the VDD. These current mirrors reduce the impact of supply voltage variations. The proposed circuit is implemented in a $0.35{\mu}m$ CMOS technology. The BGR circuit occupies $0.024mm^2$ of the die area and consumes $200{\mu}W$ from a 5 V supply voltage at room temperature. Experimental results demonstrate that the PSRR of the voltage reference achieved -118 dB at frequencies up to 1 kHz and -55 dB at 1 MHz without additional circuits for the curvature compensation. A temperature coefficient of $60 ppm/^{\circ}C$ is obtained in the range of -40 to $120^{\circ}C$.