• 미생물학회지
• /
• 제45권2호
• /
• pp.119-125
• /
• 2009

동토지대 거대 담수호에 서식하는 종속영양세균 군집의 생태학적 기능을 파악하기 위하여, 몽골 북부의 동토지대 경계에 위치한 스굴 호수에서, 전체 세균군집의 구조와 유기물질을 분해할 수 있는 미생물 군집의 구조를 수심별로 비교 분석하였다. 환경인자 분석결과, 수심 5~10 m 사이에서 thermocline과 chemocline이 관찰되었다. Denaturing gradient gel electrophoresis (DGGE)로 전체 세균군집의 구조를 수심별로 비교한 결과 0~5 m 사이에서 군집구조의 변화가 컸고, 10 m 이상에서는 Acidovorax facilis를 위주로 비교적 안정된 군집을 형성하였다. $10^{\circ}C$에서 고분자 유기물 분해 활성도(protease, cellulase, amylase, lipase)가 높은 균주들을 탐색하여 23개 균주를 선별하였다. 표층수로부터 Acidovorax defluvii와 Sphingobacterium faecium이 분리되었는데 cellulase 활성이 높았다. 수심2 m, 5 m 및 10 m 이상의 시료에서 분리된 세균군집은 각각, Flavobacterium succinicans, Mycoplana bullata, A. facilis가 우점하였다. F. succinicans는 높은 protease 활성을 보였고, 수심 5 m의 M. bullata는 protease와 cellulase 활성이 있었지만, 상대적으로 약한 활성을 보였다. 수심10 m의 A. facilis 균주들은 cellulase 또는 lipase를 서로 배타적으로 발현하였다. 온도별 성장속도를 분석한 결과 표층(0~5m) 세균들은 기회성 호냉성 세균이었고, 심층($\geq$10m)에서 분리된 균주들은 $10^{\circ}C$ 이하에서 성장률이 낮았다. 심층의 저온 빈영양 상태 때문에 심층 세균들간의 경쟁에서 빠른 저온 성장이 요구되지 않고, 상층의 경우 육상 또는 식물 플랑크톤으로부터 영양물질이 공급되므로 저온에서 빠른 성장 속도를 보이는 세균들이 상층에 주로 분포하는 것으로 해석되었다. 따라서 스굴 호수수층에서 관찰된 세균군집의 종 분포와 물질분해 작용의 성층화는, 한냉대 빈영양 담수 호수에서 분해자 군집들의 생태학적 기능이 0~10 m 수심의 표층에 집중됨을 시사하였다.

• Journal of Mechanical Science and Technology
• /
• 제16권8호
• /
• pp.1127-1134
• /
• 2002

The effects of pressure and temperature on the autoignition of propane and n-butane blends were investigated using a rapid compression machine (RCM) , which is widely used to examine the autoignition characteristics. The RCM was designed to be capable of varying the compression ratio between 5 and 20 and minimize the vortex formation on the cylinder wall using a wedge-shaped crevice. The initial temperature and pressure of the compressed gas were varied in range of 720∼900 K and 1.6∼ 1.8 MPa, respectively, by adjusting the ratio of the specific heat of the mixture by altering the ratio of the non-reactive components (N$_2$, Ar) under a constant effective equivalence ratio (ø$\_$f/= 1.0) The gas temperature after the compression stroke could be obtained from the measured time-pressure record. The results showed a two-stage ignition delay and a Negative Temperature Coefficient (NTC) behavior which were the unique characteristic of the alkane series fuels. As the propane concentration in the blend were increased from 20% and 40% propane, the autoignition delay time increased by approximately 41 % and 55% at 750 K. Numerical reduced kinetic modeling was performed using the Shell model, which introduced some important chemical ideas, represented by the generic species. Several rate coefficients were calibrated based on the experimental results to establish an autoignition model of the propane and n-butane blends. These coefficients can be used to predict the autoignition characteristics in LPG fueled Sl engines.

• 한국지진공학회논문집
• /
• 제20권4호
• /
• pp.245-256
• /
• 2016

In the companion paper (I - Database and Site Response Analyses), site-specific response analyses were performed at more than 300 domestic sites. In this study, a new site classification system and design response spectra are proposed using results of the site-specific response analyses. Depth to bedrock (H) and average shear wave velocity of soil above the bedrock ($V_{S,Soil}$) were adopted as parameters to classify the sites into sub-categories because these two factors mostly affect site amplification, especially for shallow bedrock region. The 20 m of depth to bedrock was selected as the initial parameter for site classification based on the trend of site coefficients obtained from the site-specific response analyses. The sites having less than 20 m of depth to bedrock (H1 sites) are sub-divided into two site classes using 260 m/s of $V_{S,Soil}$ while the sites having greater than 20 m of depth to bedrock (H2 sites) are sub-divided into two site classes at $V_{S,Soil}$ equal to 180 m/s. The integration interval of 0.4 ~ 1.5 sec period range was adopted to calculate the long-period site coefficients ($F_v$) for reflecting the amplification characteristics of Korean geological condition. In addition, the frequency distribution of depth to bedrock reported for Korean sites was also considered in calculating the site coefficients for H2 sites to incorporate sites having greater than 30 m of depth to bedrock. The relationships between the site coefficients and rock shaking intensity were proposed and then subsequently compared with the site coefficients of similar site classes suggested in other codes.

• 한국초전도ㆍ저온공학회논문지
• /
• 제5권1호
• /
• pp.111-117
• /
• 2003

In the design of the split type free displacer Stilting cryocooler the motion of the displacer is very important to decide the cooling capacity, which depends upon the working gas pressure, the swept volume in the compression space and the expansion space, operating frequency, the phase shift between piston and displacer, etc. In this study, Stirling cryocooler actuated by the electric farce of the dual linear motor is designed and manufactured. Cool down characteristics of the cold end with laser displacement sensor in the expander of the Stilting cryocooler is evaluated. The charging pressure was 15kg$_{f}$/$\textrm{cm}^2$ and operating frequency was 50Hz. Input power and the lowest temperature were about 32W and 67K, respectively. And, displacement of the piston is measured by LVDTs (Linear Variable Differential Transformers), displacement of thedisplacer is measured by laser optic method, and phase shift between piston and displacer is discussed. As the peak-to-peak pressure of the compressor was increased, peak-to-peak displacement of the displacer was increased. The peak-to-peak displacement of the displacer increases in the range of 0 - 64.5Hz(resonant frequency of the displacer), but decreases steeply when the operating frequency is bigger than the resonant frequency. Finally when the phase shift between displacements of the Piston and displacer is 45。, operating frequency is optimum and is decided by resonant frequency of the expander, mass and cross section area of the displacer and constant by friction and flow resistance.e.

• 한국전자파학회논문지
• /
• 제18권11호
• /
• pp.1262-1270
• /
• 2007

본 논문에서는 feedforward와 post-distortion 기법을 이용하여 평형 증폭기 내에서 발생하는 혼변조 왜곡 성분을 제거할 수 있는 새로운 왜곡 상쇄 메커니즘인 cross post-distortion 선형화 기법을 제안한다. 출력 동적 영역과 대역폭 측면에서 제안하는 선형화 방식은 기존의 feedforward 방식에 뒤지지 않는 성능을 가지고 있으면서 상대적으로 높은 효율을 제공한다. 이론적 뒷받침을 위해 제안하는 시스템과 feedforward 방식의 전력 증폭기와 오차증폭기의 전력 용량을 비교 분석하였고, IMT-2000 대역에서 실제 구현을 통하여 이를 실험적으로 뒷받침하였다. 최대 출력 전력 240 W의 기지국용 상용 대전력 증폭기에 적용했을 때, wideband code division multiple access (WCDMA) 4FA 신호에 대하여 평균 출력 전력 40 dBm에서 약 18.6 dB의 개선 효과를 얻었다. 제작된 전력 증폭기는 WCDMA 신호 기준으로 feedforward 방식에 비해 약 2 % 개선된 효율을 보였다.

• 한국근적외분광분석학회:학술대회논문집
• /
• 한국근적외분광분석학회 2001년도 NIR-2001
• /
• pp.3112-3112
• /
• 2001

Near-Infrared Spectroscopy (NIRS) was investigated aiming at the identification of falsified drugs. The identification is based on comparison of the NIR spectrum of a sample with a typical spectra of an authentic drug using multivariate modelling and classification algorithms (PCA/SIMCA). Two spectrophotometers (Brimrose - Luminar 2000 and 2030), based on acoustic-optical filter (AOTF) technology, sharing the same controlling computer, software (Brimrose - Snap 2.03) and the data acquisition electronics, were employed. The Luminar 2000 scans the range 850 1800 nm and was employed for transmitance/absorbance measurements of liquids with a transflectance optical bundle probe with total optical path of 5 mm and a circular area of 0.5 $\textrm{cm}^2$. Model 2030 scans the rage 1100 2400 nm and was employed for reflectance measurement of solids drugs. 300 spectra, acquired in about 20 s, were averaged for each sample. Chemometric treatment of the spectral data, modelling and classification were performed by using the Unscrambler 7.5 software (CAMO Norway). This package provides the Principal Component Analysis (PCA) and SIMCA algorithms, used for modelling and classification, respectively. Initially, NIRS was evaluated for spectrum acquisition of various drugs, selected in order to accomplish the diversity of physico-chemical characteristics found among commercial products. Parameters which could affect the spectra of a given drug (especially if presented as solid tablets) were investigated and the results showed that the first derivative can minimize spectral changes associated with tablet geometry, physical differences in their faces and position in relation to the probe beam. The effect of ambient humidity and temperature were also investigated. The first factor needs to be controlled for model construction because the ambient humidity can cause spectral alterations that should cause the wrong classification of a real drug if the factor is not considered by the model.

• 한국학교보건학회지
• /
• 제16권2호
• /
• pp.97-110
• /
• 2003

The purpose of this study is to find out the relationship between internet addiction and mental health of 5-6th grade students in elementary schools and to provide some basic data to develop a program for prevention and treatment of internet addiction. The study is the research of the descriptive correlation and the subjects of the study were 643 students from 5th and 6th year children of four elementary schools in four districts which are located in G city. The data were analyzed by SAS program with frequency, percentage, means, standard deviation, x2-test, ANOVA and Pearson's Correlation Coefficient. The results were as follows: 1. In the demographic characteristics of the subjects, the boys were 50.5%, girls 49.5% and 5th grade students were 48.4%, 6th grade 51.6%. The purposes of the internet using were e-mail 40.3%, game 37.5%. 2. In the degree of the internet addiction were 4.5% of addiction, 38.7% of addiction tendency and 56.8% of non-addiction. 3. The score range of the degree of the mental health index of the subjects' were 26-28, mean 47.8. 4. There were significant differences in mental health index(F=34.01, p= .000) to the degree of the internet addiction. 5. There were significant negative correlation between the degree of internet addiction and the mertal health index(r=0.342, p= .000). The result of the study showed the students who are in high-grade in elementary school have already addicted to using of the internet as much as the youth and the more they addicted to the internet, the lower mental health index they have. According to increasing of the using internet among the elementary school students, the internet addiction of them have increased. Therefore, it is necessary to develope a program for prevention and treatment of the internet addiction.

• Applied Biological Chemistry
• /
• 제46권2호
• /
• pp.69-73
• /
• 2003

병원에서 분리한 azole계 항진균성 항생물질에 대한 내성을 가지고 있는 Candida albicans에 대해 강한 활성을 가지는 항진균성 물질을 Bacillus subtilis LAM 97-44의 배양액으로부터 분리 정제한 후 그 특성을 조사하였다. 원심분리한 배양상등액을 butanol 추출, Diaion HP-20과 Dowex-50 adsorption chromatography, silica gel flash chromatography와 HPLC로 정제하였고 TLC와 HPLC로 확인하여 그 물질을 LAM-44A라 명명하였다. LAM-44A는 pH와 열에 매우 안정하였으며 Candida sp., Cryptococcus sp. 등에 대해 강한 활성을 나타낸 반면에 독성은 매우 적었다. 분리한 물질은 273 m에서 최대흡광도를 가진 융점 $202^{\circ}C$의 무색분말이었으며 ninhydrin 반응결과 음성이었고 $^1H-NMR$, $^{12}C-NMR$, IR spectrum, 원소분석 등의 결과로 볼 때 분자량 282의 $C_{14}H_{34}O_5$의 화학식을 가진 물질로 동정되었다.

• Environmental Analysis Health and Toxicology
• /
• 제16권2호
• /
• pp.97-102
• /
• 2001

FMOs (Flavin-containing monooxygenases, EC1.14.13.8)는 다양한 종류의 식품, 약물이나 기타 외래 유래물질 (xenobiotics)를 산화시키는 NADPH와 $O_2$ 의존성 약물대사효소이다. 현재까지 5종의 subfamily가 존재하는 것으로 보고되어 있으며 그 중 잘 알려진 FMO3는 대표적 인 subfamily로서 주로 간에 존재한다 사람FMO에 관한 연구는 최근 들어 활성화되기 시작했으며 질소, 황이나 인 등을 포함하는 친핵성 (nucleophilic) 화합물이 대표적인 기질로 보고되어 있다. 본 연구에서는 thiocarbamide를 포함하고 있는 화합물에 대한 사람의 FMO3의 기질 특이성을 알아보고자 하였다. 사람 FMO3를 baculovirus system을 이용하여 대량으로 발현시킨 후 그 microsomal FMO3를 분리하여 thiocholine assay를 시행하였다. 그 결과 methimazole, thiourea, and phenylthiourea는 낮은 $K_{m}$ (4-10$\mu$M)간을 갖는 반면, 이보다 기질의 크기가 큰 1 ,3-diphenylthiourea, 1, 3-bis (3, 4-dichlorophenyl)-2-thiourea, 1, 1-dibenzyl-3-phenol-2-thiourea에서는 효소활성이 나타나지 않았다. 이는 사람 fM01과 비교하여 볼 때 큰 차이는 없었으며, 다른 pig, guinea pig, rat, rabbit에서 보다 받아들일 수 있는 기질의 크기가 더 제한적임을 알 수 있었다.

• 산경연구논집
• /
• 제10권8호
• /
• pp.25-32
• /
• 2019

Purpose - This study aims to explore women's beauty industry market and growth development by identifying the main factors of women's perception of skin health care. Research design, data, and methodology - The survey was conducted on women aged 20 to 60 living in Seoul. For the statistical analysis, frequency analysis, t-test and one-way ANOVA were conducted, and significant differences in p<0.05 were tested through the multiple range test of the Scheffe. The factor analysis was conducted to verify the validity of questions, and the reliability was determined by the coefficient of Cronbach's α. Results - The lower the age, the higher the perception of the skin, and women pay a higher price for skin health as a provisional customer. 'Acne care' was the most common skin condition (32.8%), 'life style' (79.8%) was the most important part of skin care. Final education was the highest level of skin care for women with a professional background (M=3.41) (F=4.028, p<.05). Conclusions - The differences in the recognition of health knowledge by age, marital status, and household monthly income were significant, but there was no difference between jobs and final education. Customers who use less skin care than customers who frequently use the skin care center were more aware of skin health, and women who have a high awareness of skin are more interested in aging and regenerating due to the skin care.