• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.8
• /
• pp.607-612
• /
• 2013

Soil ecological risk assessment requires terrestrial toxicity data based on trophic levels including plants, earthworms, nematodes, and springtails. To expand the trophic levels, it is needed to consider primary producer algae, nearly distributed in terrestrial environment, as representative terrestrial test species. In this study, we collected research cases focused on soil-related test species and exposure media from SCI papers, and analyzed exposure media, test species, test chemicals, and other test methods, for reviewing research trends of soil-related algal toxicity. Up to now, in the soil-related algal toxicity, test species were 8 cases (Pseudokirchneriella subcapitata, Chlorella vulgaris, Scenedesmus bijugatus, Chlorococcum infusionum, Scenedesmus subspicatus, Nostoc linckia, Synechococcus elongatus, and Chlorococcum sp.) and endpoints were cell count or photosynthetic pigment content. Also, 5 of exposure media were liquid medium, soil extracts, porewater, agar medium, and soil. Most of papers used algae isolated from natural soils or soil extracts. There were only one case for assessing algal toxicity in soil medium. More researches regarding algal toxicity in soil environments need to be conducted consistently.

• Journal of Korean Society of Transportation
• /
• v.22 no.2 s.73
• /
• pp.27-39
• /
• 2004

The purpose of this paper presents realistic policy alternative about recent tendency to decrease of subway-users and diminution of use efficiency which are serious problems of Busan Subway. Several policy alternatives have been studied until now, such as subway transfer impedance solution plan, introduction of subway to transfer fare discounting policy, and etc.. But, those policy alternatives are difficult to carried out, because they are less effective and overburden to financial aspect. Therefore, I made use of research on subway utilization to presuppose service improvement, as an alternative, in the transfer fare discounting system between bus and subway which might be powerful influence over subway-users. To verify this proposed study, I took advantage of Stated Preference(SP) where I estimated fare revenue and effects on fluctuation of subway-users with nested logit model based on research results. Suitable alternatives are as follows: First, If municipal government carries out transfer fare discounting policy without shortening in-vehicle time and out-of-vehicle time transfer fare, it is reasonable to discount transfer fare 50% off on the assumption of financial support as much as \6.700 million annually. Secondly, in case of application of multi-factors at a time, transfer fare discounting and in & out vehicle time, it is preferred to have no charge for transfer option with financial support as much as expected income-loss \5,600 million.

• Microbiology and Biotechnology Letters
• /
• v.34 no.2
• /
• pp.109-114
• /
• 2006

Yam has been recognized as healthy food due to its various biological activities, such as anti-obesity, antimicrobial, anticancer and immuno-stimulation activities, and its consumption has been increased during last decades. In this study, to investigate low-temperature, long-term storage of yam and to develop processed yam products, yam-putrefactive psychrotrophic bacteria were isolated from rotted yam and identified based on BBL identification system, fatty acid analysis in cell membrane and 16S rDNA sequence analysis. The putrefaction activity of isolated thirteen bacteria was evaluated using yam-slices (NaOCl-treated, autoclaved yam and without treatment), and YAM-10 and YAM-12 were identified as major psychrotrophic putrefactive bacteria. Both YAM-10 (Pseudomonas cepacia) and YAM-12 (Pseudomonas rhodesiae) bacteria grew well at 4$\sim$12$^{\circ}C$ and showed strong activity of polymer degrading enzymes, especially amylase, carboxy methyl cellulase and xylanase, at 20$^{\circ}C$. But they failed to grow at acidic pH (<5) or alkaline pH (>10). Our results suggested that the control of psychrotrophic Pseudomonas sp. by pH change and inhibition of polymer degrading enzymes, such as amy-lase, are necessary to long-term storage of yam.

• 한국생물공학회:학술대회논문집
• /
• 2002.04a
• /
• pp.453-456
• /
• 2002

The production conditions of cellulolytic enzymes by Trichoderma sp. FJ1, were optimized using response surface analysis. The culture factors which largely affected to the production of enzymes such as cultivation time, carbon source concentration, nitrogen source concentration, and composition ratio of carbon sources were employed. Optimized conditions of the factors above to each cellulolytic enzyme production was as follow: CMCase production was obtained in the conditions of cultivation time of 5.4 days, 3.5% of carbon source concentration, 0.6% of nitrogen source concentration, and 52:48 (avicel:CMC) of composition ratio of carbon sources, respectively, xylanase appeared in the conditions of 5.3 day, 3.5%, 0.8%, and 54:46, respectively, and ${\beta}-glucosidase$ were 7.0 day, 5.0%, 1.0%, and 83:17, respectively, and avicelase were 6.5 day, 4.0%, 0.9%, and 64:36, respectively. The activities of CMCase, xylanase, ${\beta}-glucosidase$, and avicelase predicted by the response surface methodology were 33.5, 52.6, 2.88, and 1.84 U/ml, respectively, and ${\beta}-glucosidase$ was enhanced up to 74% compared to that obtained in the experimental conditions.

• Journal of Educational Research in Mathematics
• /
• v.16 no.4
• /
• pp.313-326
• /
• 2006

본 연구는 중학교 2학년 141명의 학생을 대상으로 수학 창의성(Mathematical Creative Problem Solving Ability Test: KEDI, 1997)과 성격유형(Murphy-Meisgeier Type Indicator for Children: 심혜숙 김정택, 1993)과의 상관관계를 조사하였다. 자료 분석은 중학생의 성격 특성을 알아보기 위하여 유형별로 빈도와 백분율을 산출하였고, 성격유형에 따른 수학 창의성의 차이를 검증하기 위하여 평한, 표준편차, t-test, ANOVA와 Duncan 사후검증을 실시하였다. 본 연구 결과는 다음과 같다. 첫 번째, 일반 중학교 2학년과 비교해 볼 때, 선호지표에서 연구 집단의 중학생은 표준화집단(심혜숙 김정택, 1993)보다 I(2.7%), J(3.9%)가 높았다. 두 번째, 수학 창의성과 성격유형을 살펴본 결과, 기질적 측면에서 유창성, 융통성, 수학 창의성 전체에서 NF형이 SJ, SP형에 비해 의미 있게 높았고, SJ형도 SP형에 비해 의미 있게 높게 나타났다. 세 번째, 성격유형 중에서 어떤 요인이 중학교 2학년의 수학 창의성을 잘 예측해 주는지를 살펴본 결과, 직관(N), 내향(I)이 수학 창의성의 예인변인으로서 유의하였다. 이러한 결과와 관련하여 수학 창의성 검사도구 및 수학창의성 프로그램 개발 시 직관과 내향을 우선적으로 고려하여야 한다. 네 번째 NT와 {SP, SJ, NF}는 통계적으로 유의미하게 같은 수준의 집단이 아니므로 직관적사고형(NT)이 감각적 감정형(SF), 감각적 사고형(ST), 직관적 감정형(NF)과는 독립된 특별한 요인으로 보인다. 직관적사고형(NT)은 조사와 개념 학습이나 소크라테스식의 문답법적인 학습과 문제해결학습을 선호하고 독립심이 지지되는 분위기의 학급을 선호한다. 따라서 수학 창의성 증진과 관련된 교육과정이나 프로그램개발 시 조사와 개념 학습이나 소크라테스식의 문답법적인 학습과 문제해결학습을 우선적으로 고려하여야 할 것이다. 연구 결과와 관련하여 연구의 제한점과 후속연구를 위한 제언은 다음과 같다. 첫째, 연구대상이 특정지역의 중학교 2학년 학생이므로 연구결과를 우리나라 중학교 2학년으로 일반화시키는데는 무리가 있을 수 있다. 따라서 후속연구에서는 연구대상의 표집을 확대하여 볼 필요가 있다. 둘째, 수학 창의성과 성격유형간의 관계와 관련하여 수학 창의성과 성격유형의 각 하위 차원들 간에 적률 상관계수를 통해 상관관계를 분석해 보는 것이 필요하다. 셋째 직관과 내향 및 조사와 개념 학승이나 소크라테스식의 문답법적인 학습과 문제해결학습을 고려한 수학 창의성 프로그램이 개발할 필요가 있다.

• Journal of Korean Society of Environmental Engineers
• /
• v.37 no.10
• /
• pp.563-572
• /
• 2015

The purpose of this study was to model the effect of flushing discharge on algae removal by multi-purpose weir operation in Yeongsan River (Seungchon Weir) using a 3-dimensional (3D) model. The chlorophyceae Eudorina sp. formed bloom in May 2013. Flushing discharge was conducted in two different ways for algal bloom reduction. To elucidate the spatial variability, a high-resolution 3D model, ELCOM-CAEDYM, was used to simulate the spatial variations of water quality and chl-a over a month. The results showed that ELCOM-CAEDYM could reproduce highly spatially resolved field data at low cost, and showed very good performance in simulating the pattern of algal bloom occurrence. The effect of each flushing discharge operation was analyzed with the results of modeling. The results of case 1, flushing discharge using an open movable weir, showed that the algal bloom between the Seochang Bridge and the Hwangryong River junction is rapidly flushed after operating the movable weir, but the residual algae remained in the weir pool as the discharge decreased. However, the results of case 2, fixed weir overflow with a small hydropower stop, showed that most of the algae was removed after flushing discharge and the effect of algae removal was much bigger than that in case 1, as per modeling results and observed data.

• Journal of the East Asian Society of Dietary Life
• /
• v.6 no.1
• /
• pp.105-114
• /
• 1996

Certain Fungi Including Aspergillus flavus produce low molecular secondary metabolite that is toxic to human and animals, which have been termed mycotoxin. Given the proper humidity and temperature like summer in Korea, are capable of growing of those hazard fungi and elaborating mycotoxin on almost any organic substrate such as traditional foodstuffs and their raw materials including rice, barley, corn, meju, doenjang and gochujang etc. Until now, some people have examined to isolate various fungi such as Aspergillus sp., Penicillium sp. and Fusarium sp. from traditional foodstuffs and raw materials, and have screened various mycotoxin producing strains. Some mycotoxin contamination such as aflatoxin, ochratoxin, deoxynivalenol (DON) and zearalenone etc. also have been confirmed from similar above samples. But these data are different each other and inconsistent in experimental conditions and methods. Especially, almost experiments have been finished for one time. So more consistent experimental method and data are necessary to evaluate objectiely the safety of traditional foodstuffs subjected to the mycotoxin. For this purpose, we have to apply a new advanced technology to develop more simple and rapid methods for determination of mycotoxin and also have to concentrate our efforts on activation of research and accumulation of technology nth sustaining investment of financial support and enlargement of research installation. With those harmonious efforts, it should be possible to examine continuously nd systematically the mycotoxin contamination in our traditional foodstuffs and to assure the safety of them. Then we can maintain and develop the better traditional foodstuffs suited to internationalization.

• Journal of Korea Water Resources Association
• /
• v.45 no.1
• /
• pp.75-89
• /
• 2012

This study attempted to analyze statistical characteristics of historical drought of Korea through trend, periodicity and drought spell analysis by using the drought indices. Standard Precipitation Index (SPI) and Palmer Drought Severity Index (PDSI) were calculated using weather data of 59 weather stations under Korea Meteorological Administration (KMA). As a result of analysis, SP13 and SP16 showed trend of drier spring, drier winter and wetter summer in all basin of Korea. However, SPI12 and PDSI showed different trends with shorter duration drought indices. In case of wavelet transform analysis for drought periodicities, in a band of 1~2 years or below 6 years showed significant spectrum. SP13 showed strongest power spectrum near the band of 1~2 year variance, and SPI12 and PDSI showed 6 years periodicities. The results from drought spell showed that Nakdong River Basin, Geum River Basin and Youngsan River Basin were appeared as severe drought vulnerable area of Korea.

• Korean Journal of Heritage: History & Science
• /
• v.14
• /
• pp.225-250
• /
• 1981

The investigation of air fungal population in the storages to keep papers and textiles that are designated as important folk life materials or treasures was carried out from Dec. 17 to. 23, 1980. Isolation media was used for malt extract agar with chloramphnicol to prevent bacterial contamination. Isolation and identification of air fungi from the four preserved rooms were Cladosporium cladosporioides, Alternaria chlamydospora, Aspergillus fumigatus, A. versicolor, Eurotium chevalieri, Penicillium charlesii var. rapidum, P. oxalicum. P. viridicatum, Trichoderma viride, Acremomium sp., Mucor sp. and Yeast. It was found that nine species in eight genera was isolated. Among them, underscribed species in Korea was two species ; Eurotium chevalieri and Penicillium visidicatum. The fungal population of four storages was showed to be dominant species such as Cladosporium cladosporioides and the order was Acremonium, Penicillium, Aspergillus, Trichoderma, Alternaria and Eurotium. Eurotium chevalieri was ascomycetous fungi including distinctive ascospores in cleistothecia, the filamentous fungi was directly isolated from the papers and cellulose materials showing to be fourteen species in eight genera. The most species of the fungi isolated was also Cladosporium cladosporioides and the other fungi were found as Acremonium, Penicillium, Aspergillus and Trichoderma. It was confirmed that underscribed fungi were two species ; Mucor racemosus and Penicillium spinulosvm. The effect of four antifungal agents, benzoic acid, sorbic acid, dehydroacetic acid and thymol was also examined on eight species of Aspergillus, Penicillium, Cladosporium. and Tricoderma. this results were shown that more than 0.5% concentration of thymol inhibited the grow of all fungalspecies and other three chemicals appeared various inhibition zones of fungal growth depending in their different concentrations.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.20 no.3
• /
• pp.131-140
• /
• 2015

To set up unicellular cyanobacterial strains with photo-biological $H_2$ production potential, live samples were repeatedly collected from 68 stations in the coastal zone of Korea for the four years since 2005. Among 77 cyanobacterial strains established six (KNU strains, CB-MAL002, 026, 031, 054, 055 and 058) were finally chosen as the excellent strains for $H_2$ production with $H_2$ accumulation over 0.15 mL $H_2\;mL^{-1}$ under general basic $H_2$ production conditions as well as positive $H_2$ production for more than 60 hr. To explore optimum procedures for higher $H_2$ production efficiency of the six cyanobacterial strains, the inter-strain differences in the growth rate under the gradients of water temperature and salinity were investigated. The maximum daily growth rates of the six strains ranged from 1.78 to 2.08, and all of them exhibited $N_2-fixation$ ability. Based on the similarity of the 16S rRNA sequences, all the test strains were quite close to Cyanothece sp. ATCC51142 (99%). The six strains, however, were grouped into separate clades from strain ATCC51142 in the molecular phylogeny diagram. Chlorophyll- a content was 3.4~7.8% of the total dried weight, and the phycoerythrin and phycocyanin contents were half of those in the Atlantic strain, Synechococcus sp. Miami BG03511. The growth of the six strains was significantly suppressed at temperatures above the optimal range, $30{\sim}35^{\circ}C$, to be nearly stopped at $40^{\circ}C$. The growth was not inhibited by high salinities of 30 psu salinity in all the strains while strain CB055 maintained its high growth rate at low salinities down to 15 psu. The euryhaline strains like CB055 might support massive biotechnological cultivation systems using natural basal seawater in temperate latitudes. base seawater. The biological and ecophysiological characteristics of the test strains may contribute to designing the optimal procedures for photo-biological $H_2$ production by unicellular cyanobacteria.