• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.336-336
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• 2012

수명 측정법과 동시 계수 도플러 넓어짐 양전자 소멸 분광법으로 p형과 n형 실리콘 시료에 0, 3.98 MeV 에너지를 가진 $0.0{\sim}20.0{\times}10^{13}$ protons/$cm^2$ 양성자 빔 조사에 의한 결함을 측정하여 실리콘 결함 특성에 대하여 조사하였다. 양전자와 전자의 쌍소멸로 발생하는 감마선 스펙트럼의 전자 밀도 에너지를 수리적 해석 방법인 S-변수와 열린 부피 결함에 대한 측정법으로서 양전자 수명 ${\tau}1$과 ${\tau}2$, 이에 따른 밀도 I1과 I2를 사용하여, 시료의 구조 변화를 측정하였다. 본 연구에서 측정된 S-변수와 양전자 수명은 시료에 조사된 양성자의 빔 에너지에 따라 변화하기보다 양성자 조사량의 변화에 따라 결함이 증가하였으며, 양전자 수명 측정과 같은 경향을 보여준다. SRIM의 결과로써, 양성자 조사 에너지에 따른 Bragg 피크 때문에 양성자는 시료의 특정 깊이에 주로 결함을 형성하여 시료 전체에는 결함으로 잘 나타나지 않기 때문이다. 빔의 조사량에 따른 결함의 영향이 더 큰 것으로 나타났다.

• 천문학회지
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• 제37권5호
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• pp.597-600
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• 2004

A substantial number of processes have been suggested as possible contributors to the extragalactic $\gamma$-ray background (EGRB). Yet another contribution to this background will be emission produced in hadronic interactions of cosmic-ray protons with the cluster thermal gas; this class of cosmic rays (CRs) has been shown to be responsible for the EUV emission in the Coma Cluster of galaxies. In this paper we assume the CRs in the Coma Cluster is prototypic of all clusters and derive the contribution to the EGRB from all clusters over time. We examine two different possibilities for the scaling of the CR flux with cluster size: the number density of the CRs scale with the number density of the thermal plasma, and alternatively, the energy density of the CRs scale with the energy density of the plasma. We find that in all scenarios the EGRB produced by this process is sufficiently low that it will not be observable in comparison with other mechanisms that are likely to produce an EGRB.

• 한국재료학회지
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• 제20권6호
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• pp.307-311
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• 2010

Positron annihilation lifetime spectroscopy is applied to BaSrFBr : Eu film which is used for the phosphore layer, and afterwards the reliability and self-consistency of source corrections in the positron lifetime spectroscopy is investigated using a $^{22}Na$ positron emitter covered by thin foils. The positron lifetime showed no significant change through the various proton irradiation energies. It is unusual that the measurements of the defects indicate that most of the defects were likely to have been generated by X-ray radiation. This may have resulted from the Bragg peaks of the proton characteristics. The Bragg peak does not affect the defect signals enough to distinguish the lifetimes and intensities in a material that is includes multi-grains. The lifetime ($\tau_1$) associated with positron annihilations in the Ba, Br, and Eu of the sample was about 250 ps, and due to the annihilations at F-centers or defects from the irradiated protons in sample, the lifetime ($\tau_2$) was about 500 ps.

• 약학회지
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• 제50권1호
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• pp.40-46
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• 2006

Square wave voltammetric (SWV) and cyclic voltammetric (CV) behaviors of cefotaxime sodium and ceftriaxone sodium have been investigated in the potential range between -0.10 V and -1.30 V using the phosphate buffers of various pH values ($2.00{\sim}9.10$). Two main peaks observed were irreversible and protons were involved in their electrochemical reductions. The first peaks of these cephalosporin antibiotics are due to the reduction of the azomethine double bond in the methoxyimino group of the side chain at position 7. The second peaks of cefotaxime sodium and ceftriaxone sodium are related to the reductions of the ${\Delta}^3$ double bond and the dioxo moiety of the side chain at position 3, respectively. The calibration curve of cefotaxime sodium in the concentration range between $1.0{\times}10^{-7}M$ and $1.0{\times}10^{-5}M$ yielded the linearity with the correlation coefficient of 0.9998 when the first peak of the antibiotic in a phosphate buffer of pH 3.02 was measured at the conditions of frequency of 120 Hz and pulse height of 50 mV by SWV. The present fast, simple and accurate SWV assay method was applied to determine cefotaxime sodium in the commercial antibiotic powder of injection.

• 한국환경과학회지
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• 제8권2호
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• pp.249-254
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• 1999

The biosorption and desorption of Cd were carried out using brown marine algae, known as the good biosorbent of heavy metals. The content of alginate bound to light metals could be changed by the physical and the chemical pretreatment of Sargassum fluitans biomass. The Cd uptake was independent of the alginate content. In case of protonated biomass, Cd uptake was the lowest because the alginic acid of biomass was dissolved to cadmium solution during the biosorption. The maximum Cd uptake of Sargassum biomass was ranged from 79 mg/g to 139 mg/g. In case of raw biomass, the higher the alginate content of biomass, the higher was the Cd uptake. 100% of Cd and light metals sorbed in the biomass were eluted at 0.1N HCI(pH 1.1). However, the elution efficiency in $CaCl_2$ and $Ca{(NO_3)}_2$solution was varied by the concentration, the solid to liquid ratio and the pH of calcium solution. The distribution coefficient between Cd and protons in the desorption solution at pH ranged from 1.6 to 2.9 was observed on the constant stoichometric coefficient(1.3).

• 천문학회지
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• 제44권2호
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• pp.49-58
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• 2011

We calculate the energy spectra of cosmic ray (CR) protons and electrons at a plane shock with quasi-parallel magnetic fields, using time-dependent, diffusive shock acceleration (DSA) simulations, including energy losses via synchrotron emission and Inverse Compton (IC) scattering. A thermal leakage injection model and a Bohm type diffusion coefficient are adopted. The electron spectrum at the shock becomes steady after the DSA energy gains balance the synchrotron/IC losses, and it cuts off at the equilibrium momentum $p_{eq}$. In the postshock region the cutoff momentum of the electron spectrum decreases with the distance from the shock due to the energy losses and the thickness of the spatial distribution of electrons scales as $p^{-1}$. Thus the slope of the downstream integrated spectrum steepens by one power of p for $p_{br}$ < p < $p_{eq}$, where the break momentum decreases with the shock age as $p_{br}\;{\infty}\;t^{-1}$. In a CR modified shock, both the proton and electron spectrum exhibit a concave curvature and deviate from the canonical test-particle power-law, and the upstream integrated electron spectrum could dominate over the downstream integrated spectrum near the cutoff momentum. Thus the spectral shape near the cutoff of X-ray synchrotron emission could reveal a signature of nonlinear DSA.

• 대한의생명과학회지
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• 제14권4호
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• pp.239-242
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• 2008

Obesity results from a combination of genetic, environmental, and behavioral factors. Uncoupling proteins (UCP) are members of the larger family of mitochondrial anion carrier proteins (MACP). UCP separates oxidative phosphorylation from ATP synthesis with energy dissipated as heat, also referred to as the mitochondrial proton leak. UCP facilitates the transfer of anions from the inner to the outer mitochondrial membrane and the return transfer of protons from the outer to the inner mitochondrial membrane. Therefore, we investigated the genotype for the G>A polymorphism at the position -866 of UCP2 gene in Koreans and compared genotype of patients with control group. 50 patients (Male 22, Female 28), who previously underwent type 2 diabetcs (T2DM) and 30 controls (Male 14, Female 16) participated in this study. There was a weak significant association between -866 G>A polymorphism in UCP2 gene and T2DM. The present study shows that UCP2 -866 G>A polymorphism may not be associated with the pathogenesis of T2DM as opposed to the previous reports in other countries. Further studies with larger population may be needed for the development of diagnostic methods at genetic level such as DNA chip.

• 한국자기공명학회논문지
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• 제18권2호
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• pp.52-57
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• 2014

The TCP domain is a DNA-binding domain present in plant transcription factors and plays important roles in various biological functions. The hydrogen exchange rate constants of the imino protons were determined for the three DNA duplexes containing the DNA-binding sites for the TCP11, TCP15, and TCP20 transcription factors using NMR spectroscopy. The M11 duplex displays unique hydrogen exchange property of the five base pairs in the first binding site (5'-GTGGG-3'). However, the M15 and M20 duplexes lead to clear changes in thermal stabilities of these five base pairs. The unique dynamic features of the five base pairs in the first binding site might play crucial roles in the sequence-specific DNA binding of the class I TCP transcription factors.

• 공업화학
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• 제9권7호
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• pp.1018-1022
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• 1998

본 연구에서는 테트라하이드로퓨란(THF)의 개환중합반응에 의해 변형된 12-몰리브도인산의 특성 및 촉매 반응성을 살펴보았다. 기상 에탄올 전화반응에서 THF에 의해 변형된 12-몰리브도인산은 모산 촉매보다 매우 우수한 전환율 및 생성물 수율을 보였다. 변형된 12-몰리브도인산의 증가된 반응성은 변형된 헤테로폴리음이온의 구조적 유연성과 약화된 수소결합에 기인하는 것으로 판단된다. THF는 양성자 또는 결정수를 매개로 헤테로폴리산과 상호작용을 하는 것으로 나타났는데, 결정수를 중심으로 한 THF와 헤테로폴리음이온간의 상호작용이 변형된 12-몰리브도인산의 촉매 활성을 결정하는 주된 요인이었다.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.919-923
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• 2005

A bacterium capable of poly(${\gamma}$-glutamic acid) production was isolated from nonpasteurized soy sauce. It was judged to be a variety of Bacillus subtilis and designated as B. subtilis C1. B. subtilis C1 produced ${\gamma}$-PGA in the absence of exogenous glutamic acid; therefore, it is a de novo PGA­producing bacterium. The product produced by B. subtilis C1 was characterized by amino acid analysis to be composed of solely glutamic acid. However, the $H^1-NMR$ spectra showed chemical shifts of glycerol protons in addition to those of authentic ${\gamma}$-PGA, indicating that the product is in fact a bioconjugate of ${\gamma}$-PGA. The finding is unique, because the microbial production of ${\gamma}$-PGA bioconjugate has never been reported before. The molecular mass of the product was over 10,000 kDa as determined by GPC, and $97\%$ of the product was D-glutamate, indicating that L-glutamate was converted to its D-form counterpart by B. subtilis C1.