• The Journal of the Acoustical Society of Korea
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• v.36 no.4
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• pp.238-246
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• 2017

High frequency ultrasound imaging typically suffers from low sensitivity due to the small aperture of high frequency transducers and shallow imaging depth due to the frequency-dependent attenuation of ultrasound. These limitations should be overcome to obtain high-frequency, high- resolution ultrasound images. One practical solution to the problems is a high-performance signal receiver capable of detecting a very small signal and amplifying the signal with minimal electronic noise addition. This paper reports a recently developed low-noise, wideband ultrasound receiver for high-frequency, high-resolution ultrasound imaging. The developed receiver has an amplification gain of up to 73 dB and a variable amplification gain range of 48 dB over an operating frequency of 80 MHz. Also, it has an amplification gain flatness of ${\pm}1dB$. Due to these high performances, the developed receiver has a signal-to-noise ratio of at least 8.4 dB and a contrast-to-noise ratio of at least 3.7 dB higher than commercial receivers.

• Radiation Oncology Journal
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• v.9 no.1
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• pp.131-141
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• 1991

A comprehensive set of dosimetric measurements has been made on the Varian Clinac 1800 15 MV photon beam. Beam quality, percentage depth dose, dose in the build up region, output, symmetry and flatness, transmission through iead (Cerrobend), tray attenuation, isodose curves for the open and wedged fields were measured using 3 dimensional water phantom dosimetry system (including film densitometer system) and polystyrene phantoms. These dosimetric measurements sufficiently characterized the beam to permit clinical use. The depth dose characteristics of photon beam is $d_{max}$ of 3.0 cm and percentage depth dose of $76.8\%$ at 10 cm,100 cm source-surface distance, field size of $10\times10\;cm^2$ for 15 MV X-ray beam. The Output factors ranged 0.927 for $4\times4\;cm^2$ field to 1,087 for $35\times35\;cm^2$ field. The build-up level of maximum dose was at 3.0 cm and surface dose was approximately $15.5\%$ for a field size $10\times10\;cm^2$ The stability of output is $within\pm1\%$ and flatness and symmetry are $within\pm3\%$. The half value thickness (HVL) of lead is 13 mm, which corresponds to an attenuation coefficient of $0.053\;mm^{-1}$. These figures compare facorably with the manufacturesr`s specifications.

• Fashion & Textile Research Journal
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• v.19 no.6
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• pp.804-812
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• 2017

This study builds a database that can be reflected in the production of dress form for fitting by typifying the upper body shape of a senior male. This study analyzed the 3D shape data of 405 persons of the 5th Size Korea. The age range is from 50s 210 persons and 60s 205 persons. Analysis items to identify upper body shape of senior males consisted of 51 items. 3D shape data were also measured using a Geomagic Design ${\times}$ program for the analysis of the upper body of the senior male required for the dress form of this study. The reference point was based on the Size Korea 2010 3D measurement standard and created points (Back-protrusion) on shape data. As a result of the senior men type, the senior men's body type was classified into four types:1. Overall, the upper body is a large body type and the most undistorted overall body type 2. Width / Thickness Flatness is the largest and vertical length factor is the smallest abdominal obesity type 3. Severe flexion of the back part type 4. The upper body is small and the scapular bending is severe. The elderly body type showed a high distribution ratio in the type with severe flexion. The development of a dress form that reflects the cause of the finery issue can improve the fit of ready-to-wear.

• Journal of IKEEE
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• v.11 no.4
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• pp.257-264
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• 2007

The MM22 microtron has used as a cancer therapy machine from Nov. 1986 to Feb. 2006. This machine was moved and installed to a radiation research center to use as an education and research tool from treatment machine because of aging of MM22 microtron. In this paper, for extracting the electron beam from microtron, operation principle of the microtron, system characteristics of each module, and pulse structures were reviewed. The beam extraction and measurement were performed after measuring pulses of each major module and extraction trials in the beam line. After finishing the movement of MM22 microtron, the 30mA target current in the case of 10 MV X-ray beam was extracted and the beam flatness of radiation distribution was acquired within 3% error ratio after 100 MU was irradiated on X-omatV Film at SSD 100 cm and field size $10{\times}10cm^2$. As a result, the microtron movement and new installation was performed with success.

• Journal of the Korea Fashion and Costume Design Association
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• v.21 no.4
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• pp.115-126
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• 2019

The purpose of this study is to analyze the characteristics of older women's torso shapes. The data was collected from the 7th Size Korea, which featured 453 women between the ages of 70-85. A factor analysis was performed of 31 indices, including seventeen based on height and length measurements, eight based on circumference measurements, and six based on torso flattening. The torso shape was determined from seven factors: torso flatness ratio, shape of the side upper torso, vertical size of upper torso, silhouette of the torso, silhouette of the bust and abdomen, shape of the hip, and the vertical size of the back of upper torso. The torso shapes of older women were classified into three types based on the results of the factor analysis. Type 1 is called the large rectangle type. They have the lowest degree of forward bend in the torso, the largest vertical and horizontal size, a round body shape, and the upper torso is gently curved. Type 2 is called the inverted triangle type. They also have a round body shape, but the abdominal size is relatively small compared to the size of the bust, and also have an open and drooping bust, and the biggest degree of forward bend in the torso. Type 3 is called the square type. They are characterized by drooping hips, the smallest vertical and horizontal sizes, and the gentlest curve of the torso.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.1
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• pp.151-157
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• 2019

This study is about the process capability index (PCI). In this study, we introduce several indices including the index $C_{PR}$ and present the characteristics of the $C_{PR}$ as well as its validity. The difference between the other indices and the $C_{PR}$ is the way we use to estimate the standard deviation. Calculating the index, most indices use sample standard deviation while the index $C_{PR}$ uses range R. The sample standard deviation is generally a better estimator than the range R. But in the case of the panel process, the $C_{PR}$ has more consistency than the other indices at the point of non-conforming ratio which is an important term in quality control. The reason why the $C_{PR}$ using the range has better consistency is explained by introducing the concept of 'flatness ratio'. At least one million cells are present in one panel, so we can't inspect all of them. In estimating the PCI, it is necessary to consider the inspection cost together with the consistency. Even though we want smaller sample size at the point of inspection cost, the small sample size makes the PCI unreliable. There is 'trade off' between the inspection cost and the accuracy of the PCI. Therefore, we should obtain as large a sample size as possible under the allowed inspection cost. In order for $C_{PR}$ to be used throughout the industry, it is necessary to analyze the characteristics of the $C_{PR}$. Because the $C_{PR}$ is a kind of index including subgroup concept, the analysis should be done at the point of sample size of the subgroup. We present numerical analysis results of $C_{PR}$ by the data from the random number generating method. In this study, we also show the difference between the $C_{PR}$ using the range and the $C_P$ which is a representative index using the sample standard deviation. Regression analysis was used for the numerical analysis of the sample data. In addition, residual analysis and equal variance analysis was also conducted.

• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.213-219
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• 2004

In this paper, a LNA(Low Noise Amplifier) has been developed, which is operating at L-band i.e., 1452∼1492 MHz for satellite DAB(Digital Audio Brcadcasting) receiver. The LNA is designed to improve input and output reflection coefficient and VSWR(Voltage Standing Wave Ratio) by balanced amplifier. The LNA consists of low noise amplification stage and gain amplification stage, which make a using of GaAs FET ATF-10136 and VNA-25 respectively, and is fabricated by hybrid method. To supply most suitable voltage and current, active bias circuit is designed Active biasing offers the advantage that variations in $V_P$ and $I_{DSS}$ will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets $V_{gs}$ for the desired drain voltage and drain current. The LNA is fabricated on FR-4 substrate with RF circuit and bias circuit, and integrated in aluminum housing. As a reults, the characteristics of the LNA implemented more than 32 dB in gain. 0.2 dB in gain flatness. lower than 0.95 dB in noise figure, 1.28 and 1.43 each input and output VSWR, and -13 dBm in $P_{1dB}$.

• Progress in Medical Physics
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• v.12 no.2
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• pp.125-131
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• 2001

We was investigate the dosimetric characteristics of the virtual wedge and it compared to the conventional fixed wedge. Also we was evaluate the quality factor of the experimental multi-channel dosimetry system for virtual wedge. Recently virtual wedge technique and wedge fraction methods are available through the computer controlled asymmetric collimator or the independent jaw in medical linear accelerator for radiation therapy. The dosimetric characteristics are interpreted by radiation field analyzer RFA-7 system and PTW-UNIDOS system. Experimental multi-channel dosimetry system for virtual wedge was consists of the electrometer, the solid detector and array phantom. The solid detectors were constructed using commercially diodes for the assessment of quality assurance in radiotherapy. And it was used for the point dose measuring and field size scanning. The semiconductor detector and ion chamber were positioned at a dmax, 5 cm, 10 cm, 20 cm depth and its specific ratio was determined using a scanning data. Wedge angles in fixed and virtual type are compared with measurements in water phantom and it is shown that the wedge angle 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$were agree within 1$^{\circ}$ degree in 6, 10 MV photon beams. In PDD and beam flatness, experimental multi-channel disimetry system was capable of reproduceing the measured values usually to within $\pm$2.1% the statistical uncertainties of the data. It was used to describe dosimetric characteristics of virtual wedge in clinical photon beams. Also we was evaluate optimal use of the virtual wedge and improve the quality factor of the experimental multi-channel dosimetry system for virtual wedge.