• International Journal of Korean Welding Society
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• 제1권2호
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• pp.45-50
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• 2001

This paper presents application of neutron diffraction technique to the measurement of residual stresses in the T-type 20 m thick welded stainless steel plates(100$\times$50 $mm^2$ and 50$\times$50 $mm^2$). The High Resolution Powder Diffractormeter of the Korea Atomic Research Institute was utilized in the measurement. The power of nuclear reactor was 24 MWt and the measured reflection in the 220 plane (2$\theta$）was $92.66^{\circ}$. Poisson ratio of 0.265 and elastic constant of 211 GPa were applied to the calculation of stresses and strains. Three directional components such as normal, transverse, and longitudinal stresses were measured. The results showed that three components were tensile and became compressive along the y axis in the zone away from the welded center. The compressive stresses became tensile in the zone away from the center line of x axis. This may be due to the balance effect caused by the net stress to keep the specimen shape flat.

• International Journal of Korean Welding Society
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• 제1권1호
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• pp.39-43
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• 2001

In this paper, the neutron diffraction is applied to the residual stress measurement on the 20mm-thick welded stainless steel plate ($100^{\circ}$$\times$100$mm^2$). The High Resolution Powder Diffractormeter of the Korea Atomic Research Institute The power of nuclear reactor was 24 MWt and the measured reflection in the 220 plane (2$\theta$ is $95^{\circ}$and wavelength is 1.8340 ${\AA}$ . The Poisson ratio of 0.265 and elastic constant of 211 GPa are applied to the calculation of stresses and strains. Three directional components such as normal, transverse, and longitudinal stresses are measured and the results show that the most of longitudinal stress is tensile and decreases, changing to compressive depending on the distance away from the welded spot. However, transverse component is changing from tensile to compressive along the depth of the welded point.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.638-642
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• 2005

For gas hydrate exploration, long offset multichannel seismic data acquired using by the 4km streamer length in Ulleung basin of the East Sea. The dataset was processed to define the BSRs (Bottom Simulating Reflectors) and to estimate the amount of gas hydrates. Confirmation of the presence of Bottom Simulating reflectors (BSR) and investigation of its physical properties from seismic section are important for gas hydrate detection. Specially, faster interval velocity overlying slower interval velocity indicates the likely presences of gas hydrate above BSR and free gas underneath BSR. In consequence, estimation of correct interval velocities and analysis of their spatial variations are critical processes for gas hydrate detection using seismic reflection data. Using Dix's equation, Root Mean Square (RMS) velocities can be converted into interval velocities. However, it is not a proper way to investigate interval velocities above and below BSR considering the fact that RMS velocities have poor resolution and correctness and the assumption that interval velocities increase along the depth. Therefore, we incorporated Migration Velocity Analysis (MVA) software produced by Landmark CO. to estimate correct interval velocities in detail. MVA is a process to yield velocities of sediments between layers using Common Mid Point (CMP) gathered seismic data. The CMP gathered data for MVA should be produced after basic processing steps to enhance the signal to noise ratio of the first reflections. Prestack depth migrated section is produced using interval velocities and interval velocities are key parameters governing qualities of prestack depth migration section. Correctness of interval velocities can be examined by the presence of Residual Move Out (RMO) on CMP gathered data. If there is no RMO, peaks of primary reflection events are flat in horizontal direction for all offsets of Common Reflection Point (CRP) gathers and it proves that prestack depth migration is done with correct velocity field. Used method in this study, Tomographic inversion needs two initial input data. One is the dataset obtained from the results of preprocessing by removing multiples and noise and stacked partially. The other is the depth domain velocity model build by smoothing and editing the interval velocity converted from RMS velocity. After the three times iteration of tomography inversion, Optimum interval velocity field can be fixed. The conclusion of this study as follow, the final Interval velocity around the BSR decreased to 1400 m/s from 2500 m/s abruptly. BSR is showed about 200m depth under the seabottom

• 비파괴검사학회지
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• 제30권5호
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• pp.484-488
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• 2010

적외선 열화상 카메라를 이용하여 온도를 측정할 때는 측정 대상물질의 적외선 방사율이 중요하다. 적외선 방사율은 흑체와 물체의 적외선 방사 강도비로 구할 수 있으나, 상온에서는 배경의 영향으로 인해 측정하는 것은 용이하지 않다. 따라서 FT-IR를 이용하여 반사법에 의해 강판 및 강판에 코팅된 도료의 적외선 반사율을 측정하고 적외선 방사용을 구하였다. 연마된 강판은 0.06 ~ 0.10의 적외선 방사율을 나타내고 있으며, 비연마 강판은 표면조도에 의해 광학적 특성의 변화로 인한 적외선 방사율 측정에 오차가 발생하였다. 강판에 코팅된 투명도료는 적외선 흡수로 인해 방사율은 0.50 ~ 0.84 정도로 높아졌으며, 도료의 적외선 흡수 밴드에 의해 파장에 따라 방사율도 변한다. 이 실험을 통해 재료표변의 재질, 두께, 조도 등 표면 상태에 따라 적외선의 광학적 특성이 변하는 것을 확인할 수 있었다. 또한 반사법은 금속 및 금속에 코팅된 도료의 적외선 방사율 측정에 유용한 것으로 판단되며, 측정된 적외선 방사율을 적외선 열화상에 제공함으로서 측정온도의 오차를 줄일 수 있다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2002년도 정기총회 및 제4회 특별심포지움
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• pp.67-84
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• 2002

서해안 민어포 조간대 지역에서 해수면 변동과 연관된 갯벌의 퇴적구조를 파악하기 위해 고해상 천부 육상 탄성파탐사를 실시하였다. 음원으로는 5 kg 무게의 망치를 사용하였으며, 48채널의 100 Hz 지오폰을 이용하여 서로 수직한 두 측선에 대하여 1 m 간격으로 총 795 m shot의 자료를 획득하였다. 갯벌 표면이 물에 의해 포화된 상태를 이루고 있어 강성률이 매우 낮아 ground roll의 발생이 억제되었으며 기록되는 반사신호의 속도가 1500 m/s 이상이므로 일반적인 육상 천부탄성파 탐사시에 기록되는 저속도의 잡음과 분리하기가 쉽다. 그 결과 자료의 신호대 잡음비가 상당히 높고 해상도가 우수한 탄성파 단면을 얻을 수 있었다. 중합단면을 해석해 보면 조사지역의 음향기반암 상부의 퇴적층은 5 개의 층서로 나뉘어 진다. 해수면 상승에 의한 점진적 퇴적상이 전체 조사 구간에 걸쳐 우세하게 나타나고 있지만, 퇴적층 내에서 해수면 하강에 따른 침식도 관찰된다.

• 한국소프트웨어감정평가학회 논문지
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• 제16권1호
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• pp.55-63
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• 2020

광대역 광통신 시스템에 사용되는 레이저는 우수한 주파수 선택성과 모드 안정성을 가져야한다. DFB(Distributed Feedback) 레이저는 고주파로 전류 변조를 하더라도 발진 주파수의 변화가 적다. 본 연구에서는 1.55um의 파장을 갖는 DFB 레이저에서 굴절률 격자와 이득 격자가 동시에 존재할 때, 오른쪽 거울 면에 반사가 일어나지 않도록 유전막 코팅을 하여 ρ_r=0 이 되도록 하였다. 문턱에서 최소 이득을 필요로 하는 제 1모드에 대하여, 종 방향으로의 발진 모드의 빔 분포와 방사전력비 P_l/P_r를 ρ_l의 위상=π인 경우와 ρ_l의 위상=π/2인 경우에 대하여 비교 검증했다. ρ_l의 위상=π인 경우, 낮은 문턱 전류와 높은 주파수 안정성을 얻기 위해서는, κL이 8보다 커야 한다. ρ_l의 위상=π/2인 경우, 낮은 문턱 전류를 위해서는 κL=1.0이 되도록 해야 하고, 이때 발진 주파수는 격자 주파수와 일치한다. 반사 방지 코팅을 하지 않은, 두 개의 거울 면을 가진 1.55um의 파장을 갖는 DFB 레이저보다, 한쪽 거울 면에 무반사 코팅을 한 경우에 모드 선별성이 훨씬 크다.

• 동의신경정신과학회지
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• 제18권1호
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• pp.37-61
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• 2007

Objective : By examining EEG status in Korean Traditional Medicine (KTM) from the viewpoint of 'form-qi theory(形氣論)', We wish to prepare for the fundamentals of applicability of KTM diagnoses to EEG. In addition, through reinterpretation of existing Western Medicine reports from the viewpoint of KTM, We tried to find out interrelationship between them. Method : In this paper, a methodology applicable to KTM diagnoses of EEG is presented from the EEG features in waveform characteristics, personalized diversity, and cognitive activity reflection. Results : Frequency bands are assigned to corresponding one of the eight trigrams in terms of yin/yang balance, which is analogous with EEG spectrum analysis mostly used in EEG quantification. The amplitude ratio of each EEG for each frequency band gives meaningful index numbers which can be used in EEG data interpretation, and every index number is named after the sixty four hexagrams. These approaches are adopted through both '4-band classification system and '6-band classification system', and applied to pre-existing reported EEG data obtained from normal adults. These analyses show that changes and distribution pattern in the index numbers are observed as a whole on both left-right line and front-back line connecting EEG measurement cephalic electrodes. And differences in distribution pattern of three index numbers deduced from '6-band classification system' are discussed according to constitution. Conclusion : The index numbers introduced here, which are the spectral power ratio for each EEG, are based on KTM yin/yang balance. These index numbers vary according to cephalic location, so its application in terms of traditional meridian theory is strongly expected. The index number distribution also shows different patterns according to constitution.

• 한국전자파학회논문지
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• 제17권1호
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• pp.24-38
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• 2006

본 논문에서는 인공위성의 원격 측정, 명령 및 제어(TT&C)용에 적합한 원뿔 나선 안테나의 설계 및 제작에 관해 검토하였다. $2.0{\sim}2.3\;GHz$ 대역에서 동작하며 반구면상에서 양호한 이득 특성과 축비 특성을 가지도록 나선의 형상을 상용 전자장 소프트웨어를 이용하여 최적 설계하였다. 원뿐 나선의 급전을 위한 동축선 무한 벌룬은 실험적인 방법으로 구현하였다. 설계된 나선의 형상을 정밀하게 제작하는 방법을 제시하였다. 설계한 안테나를 제작하여 측정한 결과 $2.0{\sim}2.3\;GHz$ 대역에서 -18 dB 이하의 반사 계수, 4 dB 이상의 이득, 이득이 0 dB 이상인 각도가 안테나 축으로부터 ${\pm}75^{\circ}$, 축비가 5 dB 이하인 각도가 안테나 축으로부터 ${\pm}90^{\circ}$, 15 dB 이상의 전후 방비 등 양호한 특성을 얻었다.

• Restorative Dentistry and Endodontics
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• 제40권2호
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• pp.104-112
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• 2015

Objectives: This study was performed to investigate the effects of different intracanal medicaments on chemical structure and microhardness of dentin. Materials and Methods: Fifty human dentin discs were obtained from intact third molars and randomly assigned into two control groups and three treatment groups. The first control group received no treatment. The second control group (no medicament group) was irrigated with sodium hypochlorite (NaOCl), stored in humid environment for four weeks and then irrigated with ethylenediaminetetraacetic acid (EDTA). The three treatment groups were irrigated with NaOCl, treated for four weeks with either 1 g/mL triple antibiotic paste (TAP), 1 mg/mL methylcellulose-based triple antibiotic paste (DTAP), or calcium hydroxide [$Ca(OH)_2$] and finally irrigated with EDTA. After treatment, one half of each dentin disc was subjected to Vickers microhardness (n = 10 per group) and the other half was used to evaluate the chemical structure (phosphate/amide I ratio) of treated dentin utilizing attenuated total reflection Fourier transform infrared spectroscopy (n = 5 per group). One-way ANOVA followed by Fisher's least significant difference were used for statistical analyses. Results: Dentin discs treated with different intracanal medicaments and those treated with NaOCl + EDTA showed significant reduction in microhardness (p < 0.0001) and phosphate/amide I ratio (p < 0.05) compared to no treatment control dentin. Furthermore, dentin discs treated with TAP had significantly lower microhardness (p < 0.0001) and phosphate/amide I ratio (p < 0.0001) compared to all other groups. Conclusions: The use of DTAP or $Ca(OH)_2$ medicaments during endodontic regeneration may cause significantly less microhardness reduction and superficial demineralization of dentin compared to the use of TAP.

• 대한한방내과학회지
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• 제30권1호
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• pp.173-180
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• 2009

Objectives : The aim of this study was to investigate the evaluation of gastrointestinal parasympathetic nerve activity by comparing between HRV and bowel sound parameters in patients with functional dyspepsia. Methods : 62 patients (male 22, female 40) were enrolled. HRV was measured in all patients. and TP (total power), LF (low frequency density: 0.04$\sim$0.15Hz), HF (high frequency density: 0.15$\sim$0.4Hz). and LF/HF ratio were analyzed. HF band is a reflection of parasympathetic activity. and the LF-to-HF ratio is considered a marker of sympathovagal balance. Bowel sounds were recorded at the day after, and postprandial %BS was used to indicate the gastric vagal activity after eating. HRV and bowel sound parameters were compared. and correlation between them was analyzed. Results : There was no difference in LF/HF ratio between patient group and healthy group of other report. According to values of %BS, each patient was classified into a normal (>6 %BS) or hypoactivity (<6 %BS) of gastric vagus nerve group. HF component of the hypoactivity group was not significantly higher than that of the normal group. There was no correlation between HRV and bowel sound parameters. Conclusions : Because no correlation was found between HRV and bowel sound parameters in patients with functional dyspepsia, we concluded that it is not proper to evaluate gastric vagus nerve activity by HRV measurement.