• 방사선산업학회지
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• 제11권3호
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• pp.139-144
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• 2017

To evaluation of clinical usefulness for B1+RMS limits, we compared image quality of Routine, Specific absorption rate (SAR) and Root mean square (RMS) protocol. 5 volunteers underwent Magnetic Resonance Imaging (MRI) scan of the brain using three different protocols. We draw Region of interest ROI in cortex, white matter, gray matter, putamen and thalamus of axial plan. Signal to noise ratio (SNR) were evaluated in each area and Contrast to noise ration (CNR) were evaluated between white matter and gray matter. Qualitative evaluation was used to score each ROI. B1+RMS is confirmed its usefulness compared to conventional SAR standard on the aspect of improvement of image quality, reduction of scan time and easy adjusting parameter.

• Journal of Astronomy and Space Sciences
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• 제29권2호
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• pp.175-180
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• 2012

White dwarf stars have played important roles in rather diverse areas of astrophysics. This paper outlines how these stellar remnants, especially those in widely separated "fragile" binaries, have provided unique leverage on difficult astrophysical problems such as the ages of stars, the structure and evolution of the Galaxy, the nature of dark matter and even the discovery of dark energy.

• Investigative Magnetic Resonance Imaging
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• 제19권3호
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• pp.186-190
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• 2015

Acute disseminated encephalomyelitis (ADEM) is a demyelinating and inflammatory condition of the central nervous system, occurring predominantly in white matter. ADEM involving the rhombencephalon without affecting the white matter is very rare. Here, we present an unusual case of ADEM involving only the rhombencephalon in a 4-year-old Asian girl. The patient complained of pain in the right lower extremities, general weakness, ataxia, and dysarthria. The initial brain CT showed subtle ill-defined low-density lesions in the pons and medulla. On brain MRI, T2 high signal intensity (T2-HSI) lesions with mild swelling were present in the pons, both middle cerebellar peduncles, and the anterior medulla. The initial diagnosis was viral encephalitis involving the rhombencephalon. Curiously, a cerebrospinal fluid (CSF) study revealed no cellularity, and negative viral marker findings. Three weeks later, follow up brain MRI showed that the extent of the T2-HSI lesions in the brain stem had decreased. After reinvestigation, it was found that she had a prior history of upper respiratory infection. In this case, we report the very rare case of a patient showing isolated involvement of the rhombencephalon in ADEM, mimicking viral rhombencephalitis on CT and MR imaging. ADEM can involve unusual sites such as the rhombencephalon in isolation, without involvement of the white matter or deep gray matter and, therefore, should be considered even when it appears in unusual anatomical areas. Thorough history taking is important for making a correct diagnosis.

• Journal of Ginseng Research
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• 제21권1호
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• pp.53-60
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• 1997

The changes in aldehyde dehydrogenase(ALDH, E.C. 1.2.1.3.) activity in neurons and astrocytes isolated from rat brains were investigated after administration of ethanol and Korean red ginseng(Panax ginseng C.A. Meyer) saponln. The cerebral ALDH activity with acetaldehyde and Propionaldehyde was higher in the white matter than in the gray matter. However, using indole-3-a-cetaldehyde and 3,4-dihydroxyphenylacetaldehyde as substrates, there was no significant difference in activity between two regions in cerebrum. In ethanol treated group, ALDH activity with all the substrates in the gray and white matter was lower than in normal group. In ethanol-saponin treated group, the enzyme activity in the white matter remarkably Increased. The ALDH activity in neurons isolated from cerebral cortex in ethanol-treated group was lower than in normal group. In ethanol-saponin treated group, neuronal ALDH activity with propionaldehyde was significantly recovered but not with Indole-3-acetaldehyde. In astrocytes, although the ALDH activity with propionaldehyde in the ethanol-treated group was not changed as compared with normal group, considerable increase in activity was found in ethanol-saponin treated group. These results suggest that Korean red ginseng saponin may protect the neuronal functions from the toxic effects of acetaldehyde derived from ethanol by stimulation of ALDH activity in astrocytes surrounding nerve cells.

• 방사선산업학회지
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• 제12권4호
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• pp.267-276
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• 2018

A Hoffman 3D Brain Phantom was used to evaluate two PET/CT scanners, BIO_40 and D_690, according to the radiation dose of CT (low, medium and high) at a fixed kilo-voltage-peak (kVp) with the tube current(mA) varied in 17~20 stages(Bio_40 PET/CT scanner: the tube voltage was fixed to 120 kVp, the effective tube current(mAs) was increased from 33 mAs to 190 mAs in 10 mAs increments, D_690 PET/CT scanner: the tube voltage was fixed to 140 kVp, tube current(mA) was increased from 10 mAs to 200 mAs in 10 mAs increments). After obtaining the PET image, an attenuation correction was conducted based on the attenuation map, which led to an analysis of the difference in the image. First, the ratio of white to gray matter for each scanner was examined by comparing the coefficient of variation (CV) depending on the average ratio. In addition, a blind test was carried out to evaluate the image. According to the study results, the BIO_40 and D_690 scanners showed a <1% change in CV value due to the tube current conversion. The change in the coefficients of white and gray matter showed that the Z value was negative for both scanners, indicating that the coefficient of gray matter was higher than that of white matter. Moreover, no difference was observed when the images were compared in a blind test.

• Investigative Magnetic Resonance Imaging
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• 제14권2호
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• pp.103-114
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• 2010

목적 : 자기공명영상을 이용한 치매연구에서 삼차원 T1강조 뇌 구조 영상으로 뇌기능을 분석할 경우 복셀 기반 형태분석 방법이 이용 된다. 그러나 일반적으로 The Montreal Neurological Institute (MNI) 152 라는 젊은 서양성인 뇌로 만들어진 표준판에 정규화되고 이는 분석오차가 생길 수 있어 한국 노인 및 치매환자의 뇌를 분석할 경우 부정확한 결과를 초래한다. 따라서, 본 연구의 목적은 뇌 분석을 최적화 하기 위해 한국 노인 및 치매 환자의 뇌 구조 영상의 표준판을 개발하는데 있다. 대상 및 방법 : 검사장비는 3테슬러를 이용하였으며 8채널 SENSE (sensitivity encoding) 머리코일을 이용하였다. 펄스열은 삼차원 T1 강조 터보 경사자장 타입으로 뇌의 해부학 영상을 획득하였다. 신경심리 검사 점수결과에 따라 정상 노인 43명, 경도인지장애 환자 44명, 알츠하이머성 치매 환자 36명 의 세 그룹으로 나누었다. 일반 선형 모델 방정식을 사용하여 나이와 성별 및 질환간의 차이에 의한 인자를 고려 하였으며, 평가된 인자는 쌍일치 접근 방법으로 한국 노인과 치매 환자의 뇌 표준판을 만들었다. 두 표준판의 Talairach 기준 점에 따른 평균거리와 뇌실의 거리를 계산하였다. 또한 뇌 전체 영역에서 회백질과 백질을 확률이 50% 이상인 복셀 개수를 세어 회백질과 백질의 영역을 계산하였다. 결과 : 최종 뇌 표준판은 MNI152뇌 표준판과 비교했을 경우 공간 분해능이 높았고, 평균거리와 뇌실의 크기에서 차이가 있었다. 회백질 및 백질의 영역은 본 연구에서 개발한 뇌 표준판의 회백질과 백질 모두에서 더 적었고, 백질보다 회백질에서 더 많은 차이가 있었다. 결론 : 본 연구에서 개발한 한국 뇌 표준판은 앞으로 한국 노인과 치매환자의 질환을 분석하는 연구에 유용할 것으로 생각된다.

• Journal of Astronomy and Space Sciences
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• 제39권2호
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• pp.59-65
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• 2022

In this paper we propose a new perspective for explaining galaxy rotation curves. We conjecture that there is a gravitational moment of inertia which, together with gravitational mass, contributes to the gravitational potential. We substantiate a formula for the potential created by the moment of inertia. We validate our model by computing orbital rotation velocities for several galaxies and showing that computed rotation velocities correspond to the observed ones. Our proposed approach is capable of accounting for constant gas velocities outside of a galactic disc without relying on the dark matter hypothesis. Furthermore, it addresses several problems faced by the application of the dark matter hypothesis, e.g., the absence of inward collapse of dark matter into a galaxy, the spherical distribution of dark matter around galaxies, and absence of traces of the effect of dark matter in two ultra-diffuse galaxies, NGC 1052-DF2, and NGC 1052-DF4.

• 한국초지조사료학회지
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• 제17권2호
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• pp.157-166
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• 1997

This study was carried out with aim to find out a tall fescue cultivar which is palatable and resistant to hot climate, and a white clover cultivar which is less competitive with other grasses. Pastures with 3 treatments (TI: Fawn, tall fescue + Regal, white clover + orchardgrass + perennial ryegrass, T2: Roa, tall fescue + Regal, white clover + orchardgrass + perennial ryegrass, T3 : Roa, tall fescue + Tahora, white clover + orchardgrass + perennial ryegrass) were established by oversowing. Under continuous grazing, dry matter yield, soil characteristics, botanical composition and nutrient contents of forages were investigated during the grazing seasons 60m 1994 to 1996. No significant difference were found in establishment percents, physical and chemical characteristics of soil, and nutrient contents of forages between 3 treatments(P>0.05). Dry matter yield of TI, T2 and T3 were 24,188, 23,827 and 23,578kg/ha, respectively. Fawn and Roa, tall fescue cultivars occupied 6.1 and 4.8% of the total plants in 1994, 14.4 and 11.5 % in 1995, and 28.4% and 17.7% in 1996, respectively. These results indicate that Fawn, tall fescue dominantly occupied with time more than Roa, tall fescue. There were no differences in percentage of Regal and Tahora, white clover cultivars(P > 0.05), showing 4.2 and 2.4% in 1994, 16.1 and 17.3% in 1995, and 2.4 and 1.0% in 1996, respectively. The percentage of orchardgrass on mixed pasture decreased after summer season of high temperature, but percentage of Roa, tall fescue slowly increased with time firom 1994 to 1996.

• 한국토양비료학회지
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• 제50권6호
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• pp.644-652
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• 2017

Clover, a legume crop, is a landscape crop and green manure crop that can be sowing in spring. Clover serves various roles such as landscape composition, weeds suppressing, prevention of soil loss and nutrients on sloping, atmosphere purification, and supplying nitrogen in soil. Thus, in order to utilize this crop in agricultural land, we observed its effect on growth and carbon uptake in upland soil. The plant height of clover species increased with late harvesting time and was 46.0~55.0 cm at 90 days after seeding (DAS) and the longest in red clover. The dry matter increased at 85 DAS, after that, decreased slightly. The dry matter of white clover and red clover was $3.0Mg\;ha^{-1}$ and $3.1Mg\;ha^{-1}$, respectively, and crimson clover was $2.5Mg\;ha^{-1}$, significantly lower than other clover. Crops bloomed at 90 DAS were white clover and crimson clover, the period from sowing to flowering was 78 days for crimson clover and 85 days for white clover. The nitrogen content of the clover species was $12.0{\sim}29.3g\;kg^{-1}$, with the highest of $29.3g\;kg^{-1}$ for white clover. The carbon content of clover species was similar in all clover species, but carbon uptake was high in white clover and red clover, and lowest in crimson clover. The carbon uptake of the plant increased to 85 DAS and then decreased. Based on the clover growth and carbon uptake, white clover and red clover were promising when sown in spring.

• 한국초지조사료학회지
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• 제27권2호
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• pp.101-108
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• 2007

본 연구는 초종과 파종비율을 달리한 혼파초지를 비교 검토하여 건물수량과 품질을 높일 수 있는 혼파방법을 찾고자 관행 혼파초지{conventional mixtures(CM), orchardgrass (Potomad) 50% + tall fescue (Fawn)20% + Kentucky bluegrass(Kenblue) 20% + white clover(Regal) 10%}, 레드 클로버 + 혼파초지{Red clover mixtures(RM), orchardgrass (Potomac) 40 + tall fescue 20%(Fawn) + Kentucky bluegrass (Kenblue) 10% + red clover(Kenland) 30%} 및 잔디형 초종 + 혼파초지{Turf type grass mixtures(TM), orchardgrass Potomac) 50% + turf type grass(tall fescue, Millenium 20% + Kentucky bluegrass, Midnight 10% + perennial ryegrass, Palmer III 10%) + white clover, Regal 10%)의 3처리를 두어 시험하였다. 시험은 난괴법 4반복으로 충남대학교 농과대학 초지시험포장에서 2003년 9월부터 2005년 12월까지 수행하였으며, 시험결과는 다음과 같다. 2년 평균 건물수량은 레드 클로버 + 혼파초지가 11,656kg/ha으로 관행 혼파초지(11,245kg/ha)나 잔디형 초종 + 혼파초지(9,897kg/ha)에 비하여 높은 결과를 가져왔다(p<0.05). CP 함량은 연도와 혼파초지의 유형에 관계없이 레드 클로버 + 혼파 초지가 관행 혼파초지나 잔디형 초종 + 혼파초지에 비하여 높은 결과를 보였다(p<0.05). NDF, ADF, cellulose 및 lignin과 같은 섬유소물질의 함량은 조사연도와 혼파초지의 유형에 따라 대체적으로 레드 클로버 + 혼파초지에 비하여 낮은 결과를 보였다(p<0.05). 2년 평균 CPDM 수량은 레드 클로버 + 혼파초지가 2,832kg으로 관행 혼파초지(2,372kg)나 잔디형 초종 + 혼파초지(2,266kg)에 비하여 높은 결과를 나타내었다(p<0.05). 2년 평균 DDM 수량은 레드 클로버 + 혼파초지가 8,881kg으로 관행 혼파초지(8,255kg)나 잔디형 초종 + 혼파초지(7,314kg)에 비하여 높은 결과를 얻었다(p<0.05). 2005년 5회 예취시의 식생비율은 관행 혼파초지는 orchardgrass는 45%, tall fescue 22%, Kentucky bluegrass 5% 및 white clover 24%이었으며, 레드 클로버 + 혼파초지는 orchardgrass 40%, tall fescue 22%, Kentucky bluegrass 4% 및 red clover 31%이었고, 잔디형 초종 + 혼파 초지는 orchardgrass 37%, 잔디형 초종 37%(tall fescue 23%, Kentucky bluegrass 6%, perennial ryegrass 8%) 및 white clover 23%를 유지하였다. 이상의 결과를 종합할 때, 초종과 파종비율에 따른 혼파초지의 건물수량과 사료가치의 차이를 확인할 수 있었으며, 레드 클로버 + 혼파 초지가 건물수량과 사료가치를 높이는데 효과적이었다.