• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.801-809
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• 2019

Existing Gamma Knife Radiosurgery(GKRS) for large lesions is often conducted in stages with volume or dose partitions. Often in case of volume division the target used to be divided into sub-volumes which are irradiated under the determined prescription dose in multi-sessions separated by a day or two, 3~6 months. For the entire course of treatment, treatment informations of the previous stages needs to be reflected to subsequent sessions on the newly mounted stereotactic frame through coordinate transformation between sessions. However, it is practically difficult to implement the previous dose distributions with existing Gamma Knife system except in the same stereotactic space. The treatment area is expanding because it is possible to perform the multistage treatment using the latest Gamma Knife Platform(GKP). The purpose of this study is to introduce the image-coregistration based on the stereotactic spaces and the strategy of multistage GKRS such as the determination of prescription dose at each stage using new GKP. Usually in image-coregistration either surgically-embedded fiducials or internal anatomical landmarks are used to determine the transformation relationship. Author compared the accuracy of coordinate transformation between multi-sessions using four or six anatomical landmarks as an example using internal anatomical landmarks. Transformation matrix between two stereotactic spaces was determined using PseudoInverse or Singular Value Decomposition to minimize the discrepancy between measured and calculated coordinates. To evaluate the transformation accuracy, the difference between measured and transformed coordinates, i.e., ${\Delta}r$, was calculated using 10 landmarks. Four or six points among 10 landmarks were used to determine the coordinate transformation, and the rest were used to evaluate the approaching method. Each of the values of ${\Delta}r$ in two approaching methods ranged from 0.6 mm to 2.4 mm, from 0.17 mm to 0.57 mm. In addition, a method of determining the prescription dose to give the same effect as the treatment of the total lesion once in case of lesion splitting was suggested. The strategy of multistage treatment in the same stereotactic space is to design the treatment for the whole lesion first, and the whole treatment design shots are divided into shots of each stage treatment to construct shots of each stage and determine the appropriate prescription dose at each stage. In conclusion, author confirmed the accuracy of prescribing dose determination as a multistage treatment strategy and found that using as many internal landmarks as possible than using small landmarks to determine coordinate transformation between multi-sessions yielded better results. In the future, the proposed multistage treatment strategy will be a great contributor to the frameless fractionated treatment of several Gamma Knife Centers.

• Journal of Periodontal and Implant Science
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• v.35 no.1
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• pp.133-152
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• 2005

1. 목적 Prostaglandin은 치주질환과 관련된 국소적 골 대사에 중요한 역할을 한다. ${\Delta}^{12}PGJ_2$는 생체 내에서 혈장의 존재 하에 형성되는 천연 $PGD_2$ 대사산물이며 peroxisome- proliferator에 의해 활성화되는 감마 수용체 (PPAR ${\Gamma}$)에 대해 높은 친화성을 갖는 리간드로서 핵 수용체군에 속하는 전사조절인자이다. 이 연구의 목적은 골화 과정에서 ${\Delta}^{12}PGJ_2$의 역할을 규명하기 위해, 조골세포주의 증식과 분화에 미치는 영향과 그에 관련된 세포기전을 조사하는 데에 있다. 2. 방법 인간 골육종세포주인 Saos-2 (ATCC.HTB 85)와 쥐의 조골세포주 (MC3T3-E1)를 배양한 후 실험군에 농도가 각각 $10^{-5}$, $10^{-6}$, $10^{-7}$, $10^{-8}$, $10^{-9}$ 몰인 ${\Delta}^{12}PGJ_2$와 ciglitazone (합성 PPAR 감마 길항체)를 첨가하였다. 조골세포에서 PPAR 감마의 발현을 관찰하기 위해 역전사효소-중합효소연쇄반응(RT-PCR)을 특정한 primer를 이용하여 시행하였다. 세포 증식은 1일, 2일, 3 일째에 MIT 분석법으로 측정하였고, 2 일째에 알칼리성 인산효소 (ALPase) 생산을 측정하였다. 위의 결과에서 얻은 적정한 농도에서 다양한 조골세포 분화의 표지자들-제 1 형 교원질, 알칼리성 인산효소, osteopontin 및 bone sialoprotein-에 대한 간이 정량적 역전사효소-중합효소연쇄반응 (semiquantitative RT-PCR)을 실시하였으며 골결절 형성에 대한 효과를 알아보고자 석회화 분석도 시행하였다. 3. 결과 ${\Delta}^{12}PGJ_2$와 ciglitazone 모두 Saos-2 세포주의 증식을 촉진시켰다 .$10^{-8}$ 몰의 ${\Delta}^{12}PGJ_2$와 $10^{-6}$몰의 ciglitazone을 첨가한 실험군을 대조군과 비교했을 때, 시간에 비례하여 세포 증식률이 증가되었다. 알칼리성 인산효소의 활성화 검사에서도 증식률에서와 유사한 결과를 보여주었다. 간이 정량적 RT-PCR에서는 ${\Delta}^{12}PGJ_2$로 처리한 군의 경우 제 1 형 교원질, 알칼리성 인산효소, osteopontin, 그리고 bone sialoprotein의 상대적 mRNA 수준이 유의하게 높았다. 석회화 분석에서는 MC3T3-E1 세포를 $10^{-6}$ 몰의 ${\Delta}^{12}PGJ_2$로 처리한 군과 $10^{-5}$ 몰의 ciglitazone으로 처리한 군에서 현저한 골결절 형성을 보였다. 이러한 결과들은 ${\Delta}^{12}PGJ_2$가 유용한 골 유도물질이 될 수 있으며 또한 그 작용기전이 PPAR 감마-의존형 경로와 연관되어 있음을 보여준다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.6
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• pp.767-774
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• 2008

This study investigated the effect of gamma irradiation (0.5, 1 and 2 kGy) on the microbial and physicochemical changes of apricot at $20^{\circ}C$ for 2 weeks. Total aerobic bacteria, yeasts and molds were significantly decreased with increasing dose level. Hunter's color value and hardness were decreased with increment of irradiation dose level. The contents of total sugar and reducing sugar were no significantly changed by irradiation. Hydrogen donating activity was decreased and organic acid and vitamin C contents were increased with elapse of storage periods in all samples. However, there was no significant change by gamma irradiation. Sensory acceptance of irradiated apricots had high acceptability during initial storage period, but it was decreased in comparison to nonirradiated sample with elapse of storage period. These results suggest that gamma irradiation was effective upon microbiological safety and it did not affect antioxidant activity, but not good on color and texture of apricot.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2000.11b
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• pp.161-166
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• 2000

본 논문에서는 영상 데이터의 저작권 보호를 위한 다중 워터마킹 기법을 제안한다. 다중 워터마킹은 하나의 컨텐츠에 복수개의 서로 다른 워터마크를 삽입하는 기법으로 각 워터마크들은 유일한 키로 정확한 추출이 가능해야 한다. 대역확산기법(spread spectrum)을 이용한 다중 워터마킹은 워터마크 삽입시 사용되는 키들간의 직교성(orthogonality)이 보장되어야 추출시 삽입된 워터마크들의 정확한 추출이 가능하게 된다. 따라서, 본 논문에서는 랜덤계열들을 Gram-schmidt 직교화 과정을 수행하여 직교화된 랜덤계열로 워터마크를 삽입하고 추출이 가능한 방법을 제안한다. 또한, 제안기법의 성능을 평가하기 위하여 가우시안 노이즈와 감마변환에 대하여 강인함을 보인다.

• Proceedings of the Korea Contents Association Conference
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• 2017.05a
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• pp.393-394
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• 2017

2015 개정 교육과정을 통해 소프트웨어 교육의 일환으로 프로그래밍 교육이 초등학교 정규교과에 도입된다. 프로그래밍 교육이 문제해결력에 미치는 영향에 대한 분석을 통해 효과적인 교수 학습 방법이 제시될 수 있다. 본 연구에서는 엔트리와 엔트리용 센서보드를 활용한 5차시 분량의 학습 프로그램을 개발하고 그것을 적용한 수업을 실시하였다. 수업 전 후에 문제 해결 검사도구를 활용하여 학생들의 감마파와 뇌파집중 지표의 변화를 측정하고 분석하였다. 이를 통해 효과적인 프로그래밍 교육의 필요성을 제안하였다.

• Journal of Radiation Protection and Research
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• v.29 no.1
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• pp.17-23
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• 2004

In order to save time and money needed in the purchase commonly used gamma-ray standard sources, a new radioactive standard source was manufactured by the neutron activation of some regent in the research reactor HANARO. The source was manufactured with an aqueous solution by mixing and dissolving the irradiated reagents. The manufactured source was compared with a commercial standard source. It was confirmed that it could be used as an efficiency calibration source. Also, in order to compare the variation of efficiency due to the volume difference for various containers used in radioactivity assay, the efficiency variation as a function of sample volume was investigated.

• Progress in Medical Physics
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• v.4 no.2
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• pp.49-58
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• 1993

The complex glow curves were split into isolated glow curves to be calculated the values of kinetic order, activation energy, escape frequency and density of initial trap from the independent glow curves using the mathematical method of thermally stimulated processes. The minimization of the intensity difference between measured and theoretical glow curve was done by the nonlinear least-square program. The results of the fitted curves were almost equal to the actual values of the parameters. Thermoluminescence from gamma ray irradiated ${\alpha}$-Al$_2$ $O_3$ over the range of 300K to 600K was split into six glow curves. The kinetic order, activation energy and escape frequency of first glow curve were obtained as 1, 1.12eV and 6.79X10$\^$12/sec$\^$-1/, respectively, which were similar to the results of other method. Also the parameters of the second and the third glow curve and so forth were calculated.

• Journal of Digital Convergence
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• v.11 no.7
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• pp.209-214
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• 2013

Improve the recognition performance of speech recognition systems as a method for recognizing human listening skills were incorporated into the system. In noisy environments by separating the speech signal and noise, select the desired speech signal. but In terms of practical performance of speech recognition systems are factors. According to recognized environmental changes due to noise speech detection is not accurate and learning model does not match. In this paper, to improve the speech recognition feature extraction using gamma tone and learning model using acoustic model was proposed. The proposed method the feature extraction using auditory scene analysis for human auditory perception was reflected In the process of learning models for recognition. For performance evaluation in noisy environments, -10dB, -5dB noise in the signal was performed to remove 3.12dB, 2.04dB SNR improvement in performance was confirmed.

• Nuclear Engineering and Technology
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• v.26 no.4
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• pp.555-561
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• 1994

The program of performing a fast and automatic analysis of gamma ray spectra obtained by a Multi-Channel Analyzer (MCA) is developed for the surveillance of the nuclear fuel integrity. The integrity of the nuclear fuel is confirmed by the measurement of the radiation level of the reactor coolant through the real time monitoring and the periodic sampling analysis. In Yonggwang nuclear power plane 3 and 4, the Process Radiation Monitoring System (PRMS), which is a real time monitoring system, provides a measure of the fuel integrity. Currently, its spectrometer channel can identify only one radionuclide at a time since the signal processing unit of the spectrometer channel is a Single Channel Analyzer (SCA). To improve the PRMS, it is necessary to substitute the MCA for the SCA The program is operated in a real time mode and an on-demand mode, and automatically performed for all procedures. The test results by using the National Bureau of Standards (NBS) mixed standard source are in good agreement with those from Canberra System 100 which is a commercial MCA Consequently, the developed program seems to be employed for automatic monitoring of gamma rays in nuclear power plants.

• Journal of the Korean Society of Radiology
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• v.16 no.2
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• pp.151-156
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• 2022

A detector using a small number of photosensors was designed, and the position of a scintillation pixel that interacted with gamma rays through a maximum likelihood position estimation(MLPE) was measured as a digital position. For this purpose, simulation was performed using DETECT2000, which can simulate the movement of light within the scintillator, and the accuracy of position measurement was evaluated. A detector was configured using a 6 × 6 scintillation pixel array and 4 photosensors, and a gamma ray event was generated at the center of each scintillation pixel to create a look-up table through the ratio of acquired light. The gamma-ray event generated at the new position was applied as the input value of the MLPE, and the positiion of the scintillation pixel was converted into a digital positiion after comparison with the look-up table. All scintillation pixels were evaluated, and as a result, a high accuracy of 99.1% was obtained. When this method is applied to the currently usesd system, it is concidered that the process of determining the position of the scintillation pixel will be simplified.