• 한국음향학회지
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• 제28권4호
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• pp.356-362
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• 2009

현대 사회에서는 세계 인구의 대부분이 도시에 몰려 있기 때문에, 도심의 소리는 중요한 의미를 가진다. 그 중 교통음은 가장 대표적인 도심소리 중에 하나이다. 일반적으로 도심 교통음은 환경소음으로, 대표적인 자연의 소리인 숲, 폭포소리등은 사람에게 긍정적인 효과를 주는 소리로 분류한다. 본 연구에서는 자연의 소리가 포함하는 백색잡음에 다양한 형태의 FFT보정 필터를 적용시켜, 사람이 가장 선호하는 형태의 백색잡음 주파수 특성을 발견하고 자연 소리와의 상관관계를 확인하였다. 그리고 여러 형태의 도심 교통음과 숲소리의 파형, 스펙트럼 비교를 통한 분석을 진행하였다. 분석 결과 도심 교통음이 숲소리에 비해 특정 주파수대역과 시점에 집중된 소리 에너지 특징이 있음을 발견하였으며, 이러한 특징이 사람에게 미칠 수 있는 부정적인 요소들을 확인하였다. 마지막으로 전극법 뇌파 실험을 통하여, 도심 교통음과 자연의 숲, 폭포소리를 직접 피실험자들에게 들려주어, 알파파와 베타파의 에너지 분포를 측정하였다. 측정결과 도심 교통음은 자연의 소리보다 현저하게 많은 양의 베타파를 발생 시켰으며, 반대로 자연의 소리는 많은 양의 알파파를 발생 시켰다. 이러한 결과를 통해 도심 교통음이 사람에게 미치는 부정적인 영향과 자연 소리의 긍정적인 영향을 직접적으로 확인하였다.

• 생명과학회지
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• 제34권7호
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• pp.453-464
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• 2024

간장의 발효는 원재료인 메주와 천일염에서 천이된 미생물 군집에 큰 영향을 받는 것으로 알려져 있다. 본 연구에서는 간장의 발효 고도화를 위하여 메주의 크기 변화가 간장의 미생물 군집에서 분포 변화와 분포 상관관계에 대하여 미치는 영향을 조사하였다. 메주를 전체, 삼등분하여 간장을 제조하였으며, 28일간 발효를 진행하면서 7일 간격으로 간장 시료를 수집하여 16S rRNA 유전자 기반의 미생물 군집 분석을 진행하였다. 속 수준에서 발효가 진행되면서 메주를 전체 사용하여 제조한 간장은 Chromohalobacter (7일), Pediococcus (14일), Bacillus (21일), Pediococcus (28일) 순으로, 메주를 삼등분하여 제조한 간장은 28일 연속으로 Pediococcus가 가장 우점하였다. 메주 크기를 달리한 간장들의 미생물 군집의 beta-diversity 분석 결과, 발효 7일 차와 14일 차에서 메주 크기를 달리하여 제조한 간장의 미생물 군집 분리가 유의미한 차이를 가진다고 보여주었으나 발효 21일 차와 28일 차에는 모든 실험구의 미생물 군집은 분리되지 않았다. 미생물 군집의 분리가 시각적으로 나타난 발효 7일 차와 14일 차에서 미생물 군집 차이를 부여하는 바이오마커를 조사하기 위해 선형 판별 효과 크기 분석을 수행하여 LDA size 별로 정렬하였으며, 발효 7일차에서는 Gammaproteobacteria, Firmicutes, Oceanospirillales, Halomonadaceae, Bacilli, Chromohalobacter 순으로 호염성 미생물군이, 발효 14일 차에서는 Pedioccoccus acidilactici, Lactobacillaceae, Pediococcus, Bacilli, Leuconostocaceae, Weissella 순으로 유산균군이 미생물 군집 차이를 나타내는 것으로 조사되었다. 또한 속과 종에 속하는 바이오마커 미생물군을 주요 미생물로 간주하여 상관관계를 분석한 결과, 메주 크기 별로 미생물군집 간 상관관계가 차이가 있으며, 이에 따라 메주 크기가 간장 내 미생물 간 상호작용에 영향을 미칠 수 있는 것을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.2027-2032
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• 2007

[ ${\alpha}$ ]-Synuclein is the major component of Lewy bodies and responsible for the amyloid deposits observed in Parkinson's disease. Ordered filamentous aggregate formation of the natively unfolded ${\alpha}$-synuclein was investigated in vitro with the periodic ultrasonication. The ultrasonication induced the fibrillation of ${\alpha}$-synuclein, as the random structure gradually converted into a ${\beta}$-sheet structure. The resulting fibrils obtained at the stationary phase appeared heterogeneous in their size distribution, with the average length and height of $0.28\;{\mu}m{\pm}0.21\;{\mu}m$ and $5.6\;nm{\pm}1.9\;nm$, respectively. After additional extensive ultrasonication in the absence of monomeric ${\alpha}$-synuclein, the equilibrium between the fibril formation and its breakdown shifted to the disintegration of the preexisting fibrils. The resulting fragments served as nucleation centers for the subsequent seed-dependent accelerated fibrillation under a quiescent incubation condition. This self-seeding amplification process depended on the seed formation and subsequent alterations in their properties by the ultrasonication to a state that accretes the monomeric soluble protein more effectively than their reassociation of the seeds back to the original fibrils. Since many neurodegenerative disorders have been considered to be propagated via the seed-dependent amyloidosis, this study would provide a novel aspect of the significance of the seed structure and its properties leading to the acce]erated amyloid formation.

• Archives of Pharmacal Research
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• 제25권6호
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• pp.973-977
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• 2002

The pharmacokinetic of paclitaxel (1 mg/kg, i.v.) was investigated in rabbits with carbon tetrachloride-induced hepatic failure. The area under the plasma concentration-time curve (AUC) of paclitaxel was significantly (p<0.01) increased in severe carbon tetrachloride-induced hepatic failure rabbits ($1364.54{\pm}382.07$ ng/ml$\cdot$hr) compared to that of normal rabbits ($567.52{\pm}141.88$ ng/ml$\cdot$hr), but not significantly in moderate carbon tetrachloride-induced hepatic failure rabbits ($803.1{\pm}208.81$ ng/ml$\cdot$hr). The volume of distribution (Vd) (6.25$\pm$1.56 L) and the elimination rate constant($\beta$) ($0.09{\pm}0.025{\;}hr^{-1}$) of paclitaxel in severe carbon tetrachloride-induced hepatic failure rabbits were significantly (p<0.05) decreased compared to those of normal rabbits ($11.65<{\pm}2.91$L, $0.12{\pm}0.030{\;}hr^{-1}$), but not significantly in moderate carbon tetrachloride-induced hepatic failure rabbits ($9.46{\pm}2.37$ L, $0.10{\pm}0.026{\;}hr^{-1}$). Total body clearance ($CL_t$) of paclitaxel in severe carbon tetrachloride-induced hepatic failure rabbits ($0.733{\pm}0.183$ L/hr/kg) was significantly (p<0.01) decreased compared to that of normal rabbits ($1.762{\pm}0.440$ L/hr/kg), but not significantly in moderate carbon tetrachloride-induced hepatic failure rabbits ($1.245{\pm}0.311$ L/hr/kg). The half-life(t1/2) of paclitaxel in severe carbon tetrachloride-induced hepatic failure rabbits ($7.71{\pm}2.16$ hr) was significantly (p<0.05) increased compared to that of normal rabbits ($5.75{\pm}1.44$hr), but not significantly in moderate carbon tetrachloride-induced hepatic failure rabbits ($6.77{\pm}1.76$hr). This results could be due to inhibition of paclitaxel metabolism in liver disorder rabbits since paclitaxel is essentially metabolized in liver. The findings suggest that the dosage regimen of paclitaxel should be adjusted when the drug would be administered in patients with liver disorder in a clinical situation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.680-689
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• 2011

A dynamic analysis procedure is developed to provide a comprehensive estimation of the dynamic response spectrum for locomotive's wheels running over a Pre-Stressed Concrete (PSC) box girder bridge on the Korea high speed railway. The wheel force spectrum with the bridge behavior are analyzed as the dynamic procedure for various running speeds (50~450km/h). The high-speed railway locomotive (KTX) is used as 38-degree of freedom system. Three displacements(vertical, lateral, and longitudinal) and three rotational components (pitching, rolling, and yawing). For one car-body and two bogies as well as five movements except pitching rotation components for four wheel axes forces are considered in the 38-degree of freedom model. Three dimensional frame element is used to model of the PSC box girder bridges, simply supported span length of 40m. The irregulation of rail-way is derived using the exponential spectrum density function under assumption of twelve level tracks conditions based on the normal probability procedure. The dynamic responses of bridge passing through the railway locomotive with high-speed analyzed by Newmark-${\beta}$ method and Runge-Kutta method are compared and contrasted considering the developed models of bridge, track and locomotive comprehensively. The dynamic analyses of wheel forces by Runge-Kutta method which are able to analyze the forces with high frequency running on the bridge and ground rail-way are conducted. Additionally, wheel forces spectrum and three rotational components of vehicle body for three typical running speeds is also presented.

• 대한토목학회논문집
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• 제31권2A호
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• pp.115-120
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• 2011

철근콘크리트 부재의 강도는 시공오차, 부재단면치수, 철근 및 콘크리트 재료의 역학적 특성 등의 불확실성 때문에 통계적인 변동성을 보인다. 부재 저항강도의 불확실성을 고려하고 신뢰성을 확보하기 위하여는 이러한 불확실성에 대한 정확한 평가가 필요한데, 국내의 경우 특히 철근의 역학적 특성 변동성에 대한 실험 및 연구가 활발하지 못하여 국내 설계기준작성의 기초가 되는 자료는 주로 외국의 연구 성과를 인용하고 있다. 이 논문에서는 우리나라 실정에 맞는 철근의 확률모델을 개발하기위하여 국내에서 생산된 철근의 강도특성자료를 수집하여 강도와 지름, 생산회사별로 분석하였다. 그 결과 철근의 항복강도의 확률특성은 베타분포로 모델링 하는 것이 타당한 것으로 나타났으며 공칭항복강도와 철근제조회사, 그리고 철근의 직경이 철근강도에 통계적 특성에 큰 영향은 미치지 않는 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1297-1304
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• 2006

A systematic study of the structure, energetics and spectral characteristics of substituted aminoketenes $R(NH_2)$C=C=O (R = H, $CH_3$, $NH_2$, OH, $OCH_3$, CH=$CH_2$, C$\equiv$CH, CN, CHO, NO, $NO_2$) which are highly reactive and transient intermediates in synthesis has been conducted by ab initio calculations at the MP2/6- 31G*//MP2/6-31G* level. Twenty four stable isomers of the eleven substituted aminoketenes having dihedral angles $\phi NH_2\sim120{^{\circ}}$ and $60^{\circ}$ have been identified and their optimized geometries and energies obtained. Electrostatic and steric effects on the molecular geometries have been analyzed. While the $\pi$-acceptor groups lead to planar conformations, the electron-donor groups give rise to non-planar conformations. Isodesmic substituent stabilization energies relative to alkenes have been calculated and correlation with group electronegativities established. Role of induction effect by the substituent groups and resonance effects in charge distribution in the molecules has been analyzed. An analysis of the asymmetric stretching frequencies and intensities of the C=C=O group shows that affect of non-$\pi$ acceptor substituents on the frequency is determined by the field effect (F) and resonance effect (R) parameters, the calculated intensities I (km/mol.) are correlated to group electronegativities $x$ of the substituents by the relationship I = 640.2–100.1 $x$ (r = 0.92). The $\pi$-acceptor substituents increase the intensity which may be explained in terms of their delocalizing effect on the negative charge at the $C_{\beta}$ atom.

• Journal of the Korean Wood Science and Technology
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• 제46권2호
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• pp.118-124
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• 2018

Juglans mandshurica is a fast growing hard species, which is a tree in family of Juglandaceae and has a wide distribution in China, Korea and eastern Russia. Plant materials from J. mandshurica have extensively been used in folk medicines to prevent or cure gastric, esophageal, lung and cardiac cancer. As one chain of our searching for anticomplementary agents from natural sources, two epimeric ellagitannins, [2,3-O-4,4',5,5',6,6',-hexahydroxydiphenoyl (HHDP))-(${\alpha},{\beta}$)-D-glucose] (I) and pedunculagin (II) were purified from 70% acetone extracts of the stem barks of J. mandshurica by Thin Layer Chromatography and Sephadex LH-20 column chromatography approaches. The chemical structures of the isolated compounds were characterized by MS, NMR, and a careful comparation with published literatures. The epimeric ellagitannins I and II exhibited inhibitory properties against a classical pathway of complementary system with 50 % inhibitory concentrations ($IC_{50}$) values of 65.3 and $47.7{\mu}M$, respectively, comparing with riliroside ($IC_{50}=104{\mu}M$) and rosmarinic acid ($IC_{50}=182{\mu}M$), which were used as positive controls. Thus, the work indicated both the two secondary metabolites possess excellent inhibitory activity and might be developed as potential anticomplementary chemicals.

• 대한기계학회논문집B
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• 제28권10호
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• pp.1193-1201
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• 2004

The effect of equivalence ratio and fuel/air mixing quality on the phase-resolved gas temperatures at different phases of the oscillating pressure cycle was experimentally investigated. An atmospheric pressure, optically accessible and laboratory-scale dump combustor operating on methane with heat release rate of 1.59kW was used. Temperature measurements were made using coherent anti-Stokes Raman spectroscopy (CARS) at several spatial locations fur typical unstable combustion conditions. Analysis was conducted using parameters such as phase-resolved averaged temperature, normalized standard deviation and temperature probability distribution functions (PDFs). Also the probability on the occurrence of high temperature (over 1900K) was investigated to get the information on the perturbation of equivalence ratio and NOx emission characteristics. It was shown that most of temperature histograms exhibit Gaussian profile which has short breadth of temperature fluctuation at equivalence ratio of 0.6, while beta profile was predominant for the cases of other equivalence ratios (${\Phi}$=0.55, 0.50). It was also shown that phase-resolved averaged temperature oscillated in phase with pressure cycle, while normalized standard deviations which represent temporal turbulent intensity of temperature showed nearly constant value around 0.1. The characteristics on the occurrence of high temperature also displayed periodic wave form which was very similar to the pressure signal. And the amplitude of this profile went larger as the fuel/air mixing quality became poorer. These also provided additional information on the perturbation of equivalence ratio at flame as well as NOx emission characteristics.

• 대한기계학회논문집B
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• 제24권2호
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• pp.288-297
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• 2000

This paper describes the results of an experimental investigation of the flow characteristics and the heat transfer rate on a surface by interaction of a pair of vortices. The test facility consists of a boundary-layer wind tunnel with a vortex introduced into the flow by half-delta wings(vortex generators) protruding from the surface. In order to control the strength of the two longitudinal vortices, the angles of attack of the vortex generators are varied from 20 degree to 45 degree, but spacings between the vortex generators are fixed to 4 cm. The 3-dimensional mean velocity downstream of the vortex generators is measured by a five-hole pressure probe, and the hue-capturing method using the thermochromatic liquid crystals has been used to provide the local distribution of the heat transfer coefficient. By using the method mentioned above, the following conclusions are obtained from the present experiment. The boundary layer is thinned in the regions where the secondary flow is directed toward the wall and thickened where it is directed away from the wall. The peak augmentation of the local heat transfer coefficient occurs in the downwash region near the point of minimum boundary-layer thickness. Streamwise distributions of averaged Stanton number on the measurement planes show very similar trends for all the cases(${\beta}=20^{circ},\;30^{\circ}\;and\;45^{\circ}$).