• Nuclear Engineering and Technology
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• 제54권2호
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• pp.637-643
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• 2022

Uranium and plutonium are required to be accounted in spent fuel head-end and major recovery area in pyro-process for safeguards purpose. The possibility of neutron resonance technique, as a nondestructive analysis, was simulated on isotopic fissile analysis for large scale process. Neutron resonance technique has advantage to distinguish uranium from plutonium directly in mixture. Simulation was performed on U235 and Pu239 assay in spent fuel and for scoping examination of assembly type. The resonance energies were determined for U235 and Pu239. The linearity in the neutron transmission was examined for the selected resonance energies. In addition, the limit for detection was examined by changing sample density, thickness and content for actual application. Several factors were proposed for neutron production and the moderated neutron source was simulated for effective and efficient transmission measurement. From the simulation results, neutron resonance technique is promising to analyze U235 and Pu239 for spent fuel assembly. An accurate fissile assay will contribute to an increased safeguards for the pyro-processing system and international credibility on the reuse of fissile materials in the fuel cycle.

• 한국수자원학회논문집
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• 제38권10호
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• pp.811-824
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• 2005

ADCP는 음파의 도플러 효과를 이용하여 하천을 횡단하면서 단시간에 유속과 유량을 측정할 수 있는 장비이다. 본 연구는 현장 하천에서 ADCP를 이동식으로 운용하여 측정한 유속, 유량 자료를 동일한 지점에서 측정한 유속-면적법과 비교하여 ADCP를 이용한 유속, 유량 자료의 특성을 살펴볼 목적으로 수행되었다. ADCP에 의해 측정된 수심 분포는 직접 측심에 의해 측정한 수심 분포와 거의 일치하였다. ADCP로 측정한 유속은 순간적이므로 개별 연직유속분포는 시간평균한 유속-면적법 자료와 차이가 있었으나 유속 측선의 좌우에 근접한 자료를 공간적으로 평균할 경우 그 차이는 감소하고 유사한 유속 패턴을 나타내었으며, 왕복하여 반복한 측정 자료를 평균할 경우에도 시간평균한 자료와 비슷한 연직유속분포를 나타내었다. 수평유속분포의 경우 ADCP의 개별 자료 및 이를 중간단면적법에 해당하는 구간 하폭만큼 평균한 자료 역시 유속-면적법 자료와 잘 일치하는 양상을 나타내었다. 유량의 경우 한 지점에서 수 회 이상 평균한 값은 유속-면적법과 비교하여 $0.1\%{\~}9.3\%$의 차이가 나는 것으로 조사되었으며, 반복 측정 횟수를 늘릴 경우 유속-면적법 대비 오차가 감소하는 것으로 나타났다.

• 대한소아치과학회지
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• 제29권3호
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• pp.382-388
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• 2002

전라북도 전주시 유치원 어린이 650명을 대상으로 구강내 검사 실시하여 평균 연령 4.5세 어린이 100명(남아 50명, 여아 50명)의 유치열 석고모형을 계측하여 다음과 같은 결과를 얻었다. 1. 유치의 계측자내 오차는 제1유구치에서 다소 크고, 총평균치는 0.255mm이었다. 2. 유치의 근원심 및 순(협)설측 치관 직경은 전체 유치에서 남아가 여아보다 컸다. 3. 변동계수(coefficient variation)는 남 여아 모두 유전치부위가 유구치부위에 비해 다소 큰 경향을 보였고, 근원심 및 순(협)설측 치관 직경 모두 제2유구치에서 크기변화가 가장 적게 나타났다. 4. 좌, 우측 동명치 사이의 차이를 나타내는 비대칭성에서는 상악 근원심 크기 측정을 제외하고는 근원심 및 협설측 치관 크기 측정 모두에서 제2유구치가 제1유구치보다 보다 덜 비대칭적이었다. 5. Crown index는 상악의 경우 여아보다 남아에서 큰 반면, 하악의 경우에는 유견치를 제외하고는 여아에서 컸다. Crown module은 여아보다 남아에서 컸고, 일반적인 치아크기가 유중절치에서부터 제2유구치까지 점차 증가하였다. Crown area도 여아보다 남아에서 컸으며 하악 유중절치가 가장 적은 면적을 나타냈고, 상악 제2유구치가 가장 큰 면적을 나타냈다.

• Journal of Astronomy and Space Sciences
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• 제28권4호
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• pp.267-271
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• 2011

I developed an enhanced correction method for Ricean bias which occurs in linear polarization measurement. Two known methods for Ricean bias correction are reviewed. In low signal-to-noise area, the method based on the mode of the equation gives better representation of the fractional polarization. But a caution should be given that the accurate estimation of noise level, i.e. ${\sigma}$ of the polarized flux, is important. The maximum likelihood method is better choice for high signal-to-noise area. I suggest a hybrid method which uses the mode of the equation at the low signal-to-noise area and takes the maximum likelihood method at the high signal-to-noise area. A modified correction coefficient for the mode solution is proposed. The impact on the depolarization measure analysis is discussed.

• Journal of Radiation Protection and Research
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• 제5권1호
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• pp.1-6
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• 1980

A portable count-ratemeter and a thermoluminescent detector ($CaSO_4:Dy$) have been used to obtain total gamma dose rates at approximately 50 locations during the course of several survey trips in the southeastern Korea. The purposes of these measurement were to provide a future reference data and to establish the approximate range of population exposure to the natural environmental radiation. The natural levels encountered ranged from a low of 14.6 microroentgen per hour to a high of 18.9 microroentgen per hour with a mean of $16.3{\pm}1.0$ microroentgen per hour. Among these results are the relatively high natural dose rate levels in the Masan area and Yangsan-Tongdosa area with the relatively low natural dose rate levels in the Gyeongsan-Cheongdo area and the Samrangjin-Jinyeong-Gimhae area.

• 한국대기환경학회지
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• 제19권4호
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• pp.451-465
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• 2003

The major conversion processes of SO$_2$ to sulfate are reactions in gaseous, aqueous phase and on dust surface. Using the measurement data in Ganghwa, the background area of metropolitan Seoul Area, the relative contiribution of the conversion processes are estimated. Generally, aqueous cloud if the most important conversion path followed by dust surface, gas, and aqueous aerosol. Importance of conversion on dust surface increases for the dust storm period. The total conversion rate values over the metropolitan Seoul area are between 1.5 and 8.8$\times$10$^{-11}$ mole m$^{-3}$ air.

• 한국대기환경학회지
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• 제3권1호
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• pp.47-54
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• 1987

A new method for designing air pollution monitoring newtork is presented in this study. In this method, the magnitudes and the correlation coefficients of predicted concentrations in each grid points are examined and the monitoring stations are assigned to those stations which cover the damage cost the most. This method was applied to the Ulsan-Onsan Industrial Complex. This method turned out to be much more efficient than the method of TM coordinates and the method of concentric circles prescribed in the Standard Methods for Pollution Measurement as well as the existing monitoring system established in the area. The 21 stations selected by the method of TM coordinates could cover only 64.4% of the damage cost in the area, the 16 stations by the method of concentric circles 72.1%, and the existing 21 stations 67.8%, while 11 stations were enough to cover 90% of the damage cost in the area with this method. It also was found that this method required only 24 stations to cover the entire area.

• 전자공학회논문지SC
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• 제43권1호
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• pp.7-12
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• 2006

본 논문에서는 근거리 및 광역 무선 데이터 통신 상호 연동을 통한 실시간 원격 감시 시스템을 설계 제안하였다. 근거리 망은 소출력 무선 통신용 모듈을 사용하였고 광역망은 CDMA Cellular System의 Packet Data Service를 이용하여 구현하였다. Sensor Unit에서 수집된 데이터는 Data logger를 경유하여 Host computer로 전송되어 인터넷 망을 통하여 윈격 감시 제어 된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.278-281
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• 2006

The aims of this study are to investigate rib geometries of reinforcing bars commercially available in Korea, Japan and USA, and evaluate bond performance using beam-end test specimens. Measurement of rib geometries of the bars include nominal area, average distance of rib, height of rib and an angle of rib perpendicular to bar axis. The result of this study show that rib height of Korean reinforcement bars are much less than those of Japan and USA resulting in the lowest value of relative rib area. Average bond strength of Korean D25 deformed bars is known as 9 % less than that of bars produced in USA. Bond strength depends primarily on the relative rib area. Bond strength of the high relative rib area bars produced in USA show 18% higher than that of bars produced in Korea.

• Carbon letters
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• 제10권4호
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• pp.339-344
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• 2009

Henequen fiber was air-stabilized, carbonized, and steam-activated to obtain high surface area activated henequen fiber (AHF). Thermal behavior of henequen fibers has been studied by TGA. The structural morphology and characteristics were observed by SEM and BET surface area measurement. The yield of AHF from natural henequen was in the range of 20~25 wt%. Mesopores (2~2.5 nm) were developed on the AHF as the activation temperature was raised up to $700^{\circ}C$, and the band of mesopore size distribution moved to 15~30 nm when the activation were carried out at $900^{\circ}C$ for 30 min. The specific surface area and the total pore volume were about $1394\;m^2/g$ and $1.30\;cm^3/g$, respectively at this activation conditions.