• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.433-439
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• 1996

노심 외각에 설치되어 노심 외각으로 누설되는 중성자를 검출하여 노심내의 출력 변화를 지시해 주는 노외계측기(Excore Detector)는 운전중 노심의 변화를 정확히 감지하도록 정기적으로 교정되어져야 한다. 노외계측기는 노내계측기(Incore Detector)를 통하여 측정되어진 축방향 출력편차(Axial Offset)를 이용하여 교정하고 있다. 기존의 방법은 노내계측기로 최소한 4회 노심 출력을 측정하여 최소자승법(Least Square Method)으로 상수들을 구한후 노외계측기를 교정한다. 여기서 소개되는 단순 노외계측기 교정법은 노내계측기로 2회 측정되어진 자료들을 이용하는 2점 교정법과 1회 측정되어진 자료들을 이용하는 1점 교정법으로, 계측기 반응상수(Detector Response Factor)를 계산한후 교정되어진 노외계측기의 출력편차를 측정값과 비교하였다. 위의 두가지 방법을 고리 3호기 9주기, 10주기에 적용하여 노심 운전영역(~$\pm$10%)에서 2점 교정법은 최대 1.40 %, 1점 교정법은 최대 0.63 %의 오차를 보여주고 있다. 단순 노외계측기 교정법은 노심출력을 1회 또는 2회 측정하므로 교정시간을 줄이고 제어봉의 사용을 억제하여 방사성 폐기물을 감소시키는 효과와 기존의 교정 방법과 같은 정확성을 기대할수 있다.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.76-82
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• 2000

An arc sensor system to compensate positional errors was developed on the foundation of sensor interface system to make use of the on-line shift function of industrial welding robot. Investigating the on-line shift function, we examine the quantitative relationship between the deviation from programmed path and the correction data transferred from personal computer to robot controller. The number of input parameters for weld seam tracking can be reduced by making the relationship between the deviation and the correction data during half weaving be the function of only cross time. With the results of weld seam tracking for the butt joint with V-groove and fillet joint of sheet metal, good performance was implemented. By developing the sensor interface system to compensate the positional errors, industrial welding robot can be expected to contribute to the promotion of welding automation.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.31-37
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• 2018

In the surface contamination test using the end-window Geiger-Muller type counter, the wrap is used as a method for protecting the detector exposed to the outside in order to measure the beta-rays. We analyze the effect of this method on the measurement rate and the correction factor, and wanted to make it clear to radiation workers that excessive use of the wrap can affect the measured value of the beta-rays. The experimental method was to compare and analyze the change of the beta-rays measurement counting rate and the calibration factor according to the wrap thickness using the beta-rays with different energy of 3 KBq, 1.5 KBq and 0.3 KBq. The subjects of this study were the end-window Geiger-Muller type counter which were held at the calibration center certified by Korea Laboratory Accreditation Scheme (KOLAS) in March 2012, Cl-36 (Chlorine) and Sr-90 (Strontium) were used as the source of beta radiation. The measurement counting rate decreased with increasing wrap thickness, and the calibration factor increased with increasing wrap thickness. Since the changes of the measurement counting rate and the calibration factors can reduce the accuracy of the instrument readings, but also have a significant impact on detector contamination and damage, so there is a need to find out what thickness of wrap is most effective. If we using a wraps with thickness that show a low rate of change of the measurement counting rate and the calibration factor, it will protect the detector and minimize the effect on the measured value of the beta-rays.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.1-9
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• 2010

A dynamic flow system has been developed which can be used for vacuum gauge calibration by comparison method - a calibration method in which the reading of the gauge under calibration is compared to another calibrated vacuum gauge called the "secondary standard" - and other vacuum-related experiments. The chamber of the calibration system is pumped by a turbomolecular pump (TMP), backed by a scroll pump. As maximum acceptable pressure at the inlet of a TMP is 0.1 Pa, above which the TMP decelerates, the pumping speed decreases and it becomes more difficult to adjust pressure under such circumstances. In the present work, high pressures of up to 133 Pa have been generated in the chamber of the newly developed dynamic flow control system by installing a well-designed conductance-reducer in the by-pass line and, at the same time, operating the TMP in safe mode. In addition, the gas flow and pressure distribution within the chamber have been investigated for the entire pressure range (0.1 Pa ~ 133 Pa) while generating pressure dynamically. Maximum deviations in pressure (1.6 %) were observed at point C on the chamber, which is close to the gas inlet port on the top of the chamber.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.2
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• pp.206-216
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• 2000

Predictional study for lateral change between pre- and post-orthognathic surgery has been emphasized mainly on anterior area of lateral profile; upper lip, lower lip and chin et al. So interest for lateral profile change has been less in posterior area of lateral profile and literature analyzing gonial angle change is rare. The purpose of this study is to make prediction for gonial angle change possible and to offer somewhat treatment guidance for gonial angle to be improved by investigating overall gonial angle change between pre- and post-orthognathic surgery and inquiring into factors influencing on pattern of genial angle change. For this study 35 patients were selected retrospectively. Lateral cephalometric radiographs were taken in just pre-op time, pod 1 day, pod 1 year. They were analyzed and genial angles were measured. The results were as follows : 1. Gonial angle at pod 1 day was decreased about $9.3^{\circ}$ than pre-op and gonial angle at pod 1 year was increased about $4.0^{\circ}$ than pod 1 day. So genial angle at pod 1 year was decreased about $5.3^{\circ}$ than pre-op genial angle(p<0.01). 2. Mean pre-op gonial angle was $129.4^{\circ}$, showing significantly high value than normal and mean gonial angle at pod 1 year was $124.1^{\circ}$, showing value near to normal. 3. Mean gonial angle change between pre-op and pod 1 year was decreased about $5.4^{\circ}$ in female and $5.3^{\circ}$ in male. There was no statistically significant difference between male and female(p>0.05). 4. Principal factor influencing on decreased gonial angle in gonial angle change between pre-op and pod 1 year was amount of mandibular setback. 5. Principal factor influencing on increased gonial angle in gonial angle change between pod 1 day and pod 1 year was % horizontal relapse, and it was thought that resorption and bone remodelling on posterior area in mandibular distal segment also were related to increased gonial angle. 6. It is thought that sagittal split ramus osteotomy in mandibular prognathic patients with high value of gonial angle is effective to improvement of gonial angle, and In patients who have normal range of gonial angle and are required with excessive mandibular setback, short lingual cut method, additional resection of posterior margin of distal segment, Obwegeser II method will be considerd. 7. More prudent operation and careful post-op management will be responsible for maintenance of postoperative stable gonial angle.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.330-337
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• 2018

This paper proposes a technique to analyze the flatness characteristics of the attenuator at 10Hz to $50\text\tiny{MHz}$ on the basis of $1\text\tiny{kHz}$ using a Thermal Voltage Converter and AC measurement standard. In the proposed technique, the input voltage of the attenuator for each measuring frequency is supplied at the same rate as $1\text\tiny{kHz}$ using TVC, and the flatness characteristics of the attenuator are analyzed by the voltage variation indicated in the AC measurement standard. The results of the analysis of the attenuator flatness characteristics show that the maximum uncertainty of $866{\mu}V/V$ can be measured from $10\text\tiny{dB}$ to $70\text\tiny{dB}$ and the uncertainty is reduced by about 37% compared to $2.31\text\tiny{mV}$/V using the network measurement method. The improved attenuator flatness characteristic values can be applied to the frequency flatness calibration from 2.2V to 2.2mV at the low voltage of the AC measurement standard.

• The Journal of the Acoustical Society of Korea
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• v.24 no.8
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• pp.431-440
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• 2005

The precise measurement of ultrasonic power is important to the qualify assurance and the safety of medical ultrasonic equipments In the Present work, a brier theory was introduced to determine the ultrasonic Power from the time valving balance-indication due to the radiation force acting on an absorbing target and/or other causes such as buoyancy during the repetition of on/off behavior of ultrasonic irradiation. The developed automated system measuring the ultrasonic power was described in detail with the precise mechanical alignment tool , the electric signal generation network, the control and measurement network and the appropriate procedure. The ultrasonic power measured by the developed system was compared to the reference data calibrated by the other national metrology institute at 1 MHz, 5 MHz, 10 MHz, and 15 MHz over the range 10 mW to 10 W. Their relative differences are within $5\%$.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.1
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• pp.17-24
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• 2020

The purpose of this study was to evaluate the accuracy and precision of the three-dimensional (3D) imaging system of children's facial soft tissue by comparing linear measurements. The subjects of the study were 15 children between the ages of 7 and 12. Twenty-three landmarks were pointed on the face of each subject and 16 linear measurements were directly obtained 2 times using an electronic caliper. Two sets of 3D facial images were made by the 3D scanner. The same 16 measurements were obtained on each 3D image. In the accuracy test, the total average difference was 0.9 mm. The precision of 3D photogrammetry was almost equivalent to that of direct measurement. Thus, 3D photogrammetry by the 3D scanner in children had sufficient accuracy and precision to be used in clinical setting. However, the 3D imaging system requires the subject's compliance for exact images. If the clinicians provide specific instructions to children while obtaining 3D images, the 3D device is useful for investigating children's facial growth and development. Also the device can be a valuable tool for evaluating the results of orthodontic and orthopedic treatments.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.28-37
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• 2017

Mineral trioxide aggregate have been used for many years as a pulp therapy material. The most widely used product, Proroot white $MTA^{(R)}$ has a major drawback that it causes tooth discoloration. This study assessed discoloration of crown when various MTA-based materials were placed in the coronal aspect of the root canal. Seventy-five single-rooted, unrestored premolar teeth were selected. The teeth were randomly assigned to four experimental groups, each of $Biodentine^{(R)}$, Proroot $wMTA^{(R)}$, $Endocem^{(R)}$, $RetroMTA^{(R)}$ and one negative control groups. Color measurements were utilized by the Commission International de I'Eclairage's L*a*b* system with spectrophotometer. The color was assessed eight times : initial, 1 day, 1 week, 2 weeks, 4 weeks, 8 weeks, 12 weeks, and 16 weeks after the placement. Statistical analysis was performed using the 2-way repeated analysis of variance and Bonferroni's method with p < 0.05. Proroot $wMTA^{(R)}$ induced significant decreases in $L^*$ values during experiment period. Tooth samples from the $Endocem^{(R)}$ group presented indistinct grayish color changes. The $Biodentine^{(R)}$ and $RetroMTA^{(R)}$ showed color stability. Consequently, while Proroot $wMTA^{(R)}$ and $Endocem^{(R)}$ that contain bismuth oxide as a radiopacifier showed tooth discoloration, displayed no sign of discoloration $Biodentine^{(R)}$ and $RetroMTA^{(R)}$ that contain zirconium oxide as a radiopacifier.