• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.1-15
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• 2020

This study was conducted to determine whether invasive muskrats settle in the natural ecosystem of Korea. The study also aimed to provide information on the selection of target areas, basic behavioral characteristics, and habitat use-related data, all of which are essential for effective management strategy establishment and site management. To this end, a trend in international muskrat management was identified to examine the management direction according to the settlement stage. We also secured the location of 72 domestic farmers and classified five regions in Gyeonggi-do, Chungcheongnam-do, Gyeongsangbuk-do, and Sejong Special Self-governing City into regions with high potential for natural leakage to raise the need for a quick survey. We determined that muskrats successfully settled in the natural ecosystem of Korea, based on the fact that we consistently identified a muskrat habitat at the same point for three years, from 2016 to 2018, the age of the captured population was estimated to be 1.2 years, and there had been no additional make-up factors near the habitat since 2012. The muskrats that settled in Korea showed a small home range of 0.0027 ㎢ (MCP 95%) and were estimated to show regular mobility before Spring and Autumn. Also, the areas where the muskrat habitat was observed had a high level of habitat environment disturbance and their ecological and food intake characteristics reflected that disturbance. Muskrat traces were high in hydrophyte vegetation, which can be used as a hideout in open waters and where the growth of both floating leaved plants and floating plants are prevalent. Since international invasive muskrats have already settled in the domestic ecosystem and there is concern about their proliferation in the future, the government must consider a preemptive response and scientific management.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.260-269
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• 2009

Hwabuk Dam has been under construction to reduce flood damage in Nakdong River watershed and to supply stable water for middle area of Gyeongbuk Province. Therefore, fish investigation in up and downstream of the dam was conducted from 2004 to 2008 in order to determine any negative effect on fish community due to dam construction and to use as fundamental data for conserving species diversity and maintaining stream health. According to data analysis on water quality, temperature, dissolved oxygen, pH, suspended solids, and total E-coli had seasonal variation, but they did not significantly differ in sites. However, biological and chemical oxygen demand, chlorophyll-a, nitrogen, and phosphorus representing organic matter and nutrient concentration were higher in upper site and decreased to lower site so that they differed by site. Concentration of arsenic among the heavy metals was less than 0.05 mg $L^{-1}$, which is regulated for protection of human health in water quality standard, except for 0.092 mg $L^{-1}$ in June 2005. During the study period, the total number of fish caught from the 6 sites was 10,263 representing 7 families 19 species. Among them, dominant and subdominant species were Korean chub (Zacco koreanus, 62.5%) and Chinese minnow (Rhynchocypris oxycephalus, 10.6%) which inhabit mostly in mid and upper streams, Korea. Among the 19 species, Korean endemic species were 9 species (47.4%) including Korean slender gudgeon (Squalidus gracilis majimae), Korean dark sleeper (Odontobutis platycephala), and Korean shiner (Coreoleuciscus splendidus). There was several individuals of the $1^{st}$-class endangered species, Naktong nose loach (Koreocobitis nahtongensis), caught in 2005${\sim}$2007, and no introduced species of fish was found in entire sampling period. According to result of community analysis, dominance index decreased toward lower site, but diversity and richness indices increased toward lower site. The equation of length-weight relationship on the dominant species was TW=0.000003$(TL)^{3.2603}$. The parameter b in the equation was greater than 3.0 indicating good nutritional condition in the populations. Compared to populations of Korean chub in other streams, the population in Hwabuk Dam watershed had higher mean of condition factor by size indicating better growth rate. With fish fauna and multi-metric health assessment model in each sampling attempt, index of biotic integrity (IBI) was evaluated and it resulted mostly in good (26${\sim}$35) and excellent (36${\sim}$40) condition in all sites, and the mean of IBI was the highest in site 5. The results indicate that it is very important to study not only environmental impact assessment with fish composition but also stream health assessment in order to conserve healthy aquatic ecosystem.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1150-1157
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• 2011

Streptomyces sampsonii KK1024 having strong chitinolytic activity was isolated from crab-shell rich soil at Muan, Jeolanamdo. The KK1024 produced chitinase, protease, gelatinase and lipase. When 50% of KK1024 culture broth was treated to juveniles and eggs of root-knot nematode, juvenile mortality at 3 days was 81.67% and egg hatch rate at 5 days was 2.00%. When $183.7{\mu}g\;mL^{-1}$ of crude enzyme produced by KK1024 was treated, juvenile mortality at 3 days was 96.00% and egg hatch rate at 5 days was 5.33%. At 1% of butanol extract from KK1024, juvenile mortality was highest with 90.00% and egg hatch rate was lowest with 0%. The comparison of the effect of KK1024 culture broth with only medium, synthetic fertilizer, and commercial nematicide on tomato growth and nematode infection was examined in pot trials. KK1024 culture broth showed lower number of egg mass and gall in plant, and population of juveniles in soil compared with only medium and synthetic fertilizer treatment, but not in commercial nematicide. However, the highest shoot weight and length was discovered in KK1024 culture broth. These results suggest that Streptomyces sampsonii KK1024 producing lytic enzymes and nematicidal compounds can be one of candidates for biocontrol agents against root-knot nematodes.

• Journal of Chest Surgery
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• v.42 no.2
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• pp.175-183
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• 2009

Background: Mitral valve abnormalities in the pediatric population are rare. Mitral valve replacement or pediatric mitral lesions can cause problems such as a lack of growth potential. There re only limited experiences with mitral valve repair at any institution, so the purpose of his study is to evaluate the outcomes of mitral valve repair n pediatric patients. Material and Method: Sixty-four consecutive children (28 males and 36 females) with a mean age of $5.5{\pm}4.7$ years underwent mitral valve repair for treating their congenital mitral valve disease between January 1996 and December 2005. The patients were divided into two groups: group 1 (34 patients (53.1%)) had isolated disease (mitral anomaly with or without trial septal defect or patent ductus arteriosus) and group 2 (30 patients (46.9%)) had complex disease (mitral anomaly with concurrent intracardiac disease, except atrioventricular septal defect). Result: The overall in-hospital mortality was 6.3%; group 1 had 5.9% mortality and group 2 had 10.0% mortality. The postoperative morbidity was 18.8%; group 1 and 2 had 14.7% and 23.3% postoperative morbidity, respectively, and there as no significant difference among the groups. The median follow-up was 4.6 years range: $0.5{\sim}12.2$ years). The 10-year survival rate was 95.3%. The 10-year freedom from re-operation rate was 76.1% with 10 re-operations. The majority of the functional classifications were annular dilatation and leaflet prolapse. A mean of $2.1{\pm}1.1$ procedures per patient were performed. The echocardiography that was done at the immediate postoperative period showed a significant improvement in the mitral valve function. The follow-up echocardiographic results were significantly improved. However, mitral stenosis newly developed over time, and there ere significant differences according to the repair strategies. Conclusion: The patients who underwent mitral valve repair for congenital mitral anomalies showed good results. The follow-up echocardiography revealed satisfactory short-term and long-term results. Close follow-up is necessary to detect the development of postoperative mitral stenosis or regurgitation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.2
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• pp.11-21
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• 2000

Tunnelling has been created as a great extent in view of less land space available because the growth of population in metropolitan has been accelerated at a faster pace than the development of the cities. In tunnelling, it is often faced that measures are obliged to be taken without confirmation for such abnormality as diverged movement of surrounding rock mass, growing crack of shotcrete and yielding of rockbolts. In this case, it is usually said that the judgments of experienced engineers for the selection of measure are importance and allowed us to get over the situations in many construction sites. But decrease of such experienced engineers need us to develop the new system to assist the selection of measures for the abnormality without any experiences of similar tunnelling sites. In this study, After a lot of tunnelling reinforcement methods were surveyed and the detail application were studied, an expert system was developed to predict the safety of tunnel and choose proper tunnel reinforcement system using fuzzy quantification theory and fuzzy inference rule based on tunnel information database. The expert system developed in this study have two main parts named pre-module and post-module. Pre-module decides tunnel information imput items based on the tunnel face mapping information which can be easily obtained in-situ site. Then, using fuzzy quantification theory II, fuzzy membership function is composed and tunnel safety level is inferred through this membership function. The comparison result between the predicted reinforcement system level and measured ones was very similar. In-situ data were obtained in three tunnel sites including subway tunnel under Han river. This system will be very helpful to make the most of in-situ data and suggest proper applicability of tunnel reinforcement system developing more resonable tunnel support method from dependance of some experienced experts for the absent of guide.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.7
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• pp.652-657
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• 2006

Combining ability and heterosis for $F_{1}$ population obtained $5{\times}5$ half diallel cross in sesame were estimated for six quantitative characters. The parental varieties used for diallel cross were Yangbaek and Ansan of normal type, Suwon 177 and 195 of placenta adhesion type (PA) and SIG960320-5-1-1 of indehiscent type (ID). PA and ID type are shattering-resistant sesames and Yangbaek and Ansan are shattering sesames. The high heterosis of $F_{1}$ hybrids was expressed in the number of capsules per plant (NC), grain yield per plant (GY) and number of branches per plant (NB). Shattering.ate (SR) showed high positive heterosis toward increase of seeds shattering in all the combination of $F_{1}$ generation which was presumed because the characters connected with shattering resistance of seeds were governed by recessive gene. At the analysis of combining ability, highly significant general combining ability (GCA) effects were observed on all the characters in $F_{1}$ generation, significant specific combining ability (SCA) effects were observed on the NC, GY and SR. GCA variances were greater than SCA variance, which suggested that additive gene effects were greater than other nonadditive gene effects. Considering the estimated GCA effects, Suwon 195 (PA type) was found to be good parent for SR and GY, SIG960320-5-1-1 (ID type) was poor for GY and plant height. SCA effect for NC was great in Yangbaek/Suwon 195, SCA for GY was great in Ansan/SIG960320-5-1-1, and SCA for decrease of SR was great in Ansan/Suwon177.

• Korean Journal of Culture and Social Issue
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• v.21 no.3
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• pp.551-573
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• 2015

The rise of single living has been one of the most important demographic shifts of recent decades. The solo household is a little less than 40% in Europe areas and that of Tokyo is over 45%. Being impacted this figure, the formation of single economy is the key word in World Economic Forum(WEF) 2008. Seoul' single household is increasing rapidly. Between 2000 and 2005, the growth of single person is around 34%, the population of single person reached 700,000 people. Now 20% of total household in Seoul is Single household. Living alone or solo living is not exceptional or special in Seoul Metropolitan City. The rise in single living will create pressures towards poverty and inequality and so on. Seoul should develop and prepare the urban policy for single household. We figured out the four key trends which composed of single household in Seoul. Four types of single person are like below : Gold Mr and Miss, Reserved labor forces, depressed single and silver generation. Gold group is amonst people aged 30 and 40 who is working in the area of white collar and professional. They are usually elective single person household who have chosen solo living. Reserved labor forces group is usually among 20s people who have not get the regular hob. For this group, job acquiring is the most important issue. Depressed single person household group is among people aged late 30s and 40s. Its group is the result from the broken family. The silver group is among aged over 65 that is the main issue of the aged society. In this research, we stressed that people living alone can be split into two types - elective single person households who have chosen single living, and forced single person household who have been constrained to this lifestyle by circumstances. Except gold group, the rest of the group is the forced single household who are faced to poverty. The monthly income of single person household is almost under 2 million won. Single person household is usually working in the blue collar job and service area. So, except gold group that is the smallest part of single person household, almost single person is not the target of private market, but the object of public policy.

• Korean Journal of Environment and Ecology
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• v.34 no.5
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• pp.358-371
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• 2020

As climate change is expected to lead to a severe reduction of biodiversity, studies to investigate the reasons for habitat loss, growth decline, and death of Korean fir (Abies koreana Wilson), endangered alpine/subalpine species in Korea, have been conducted for years but found no clear answer yet. This study reviewed previous studies on Korean fir published in the journals in the past 40 years, 1980 through 2020, into 10-year units, examined the study trend by period, region, and subject with a focus on ecological studies, and analyzed the study results. The ecological studies were categorized into evolutionary ecology, physiological ecology, population ecology, and landscape ecology. Based on the results, we suggested the required research fields in the future. We found a total of 73 papers published in the past 40 years and 48 (65.8%) of them published in the past 10 years. In terms of region, Mt. Halla accounted for the most as 41 papers were on it. In terms of ecological subjects, the physiological ecology accounted for the most with 38, and the evolutionary ecology accounted for the least with 10. The review of the study results showed that many studies identified water stress caused by the water resource imbalance due to temperature increase and spring precipitation reduction following climate change as the main reason for the decline and habitat loss of Korean fir. However, recent studies suggested other factors, such as soil environment, disturbing organisms, and climatic events. The cause of the decline and death of the Korean fir not yet being clearly identified is that most of the studies dealt with the basic content, were carried out intermittently, and were concentrated in some regions. Therefore, we need long-term studies with advanced technology in each study subject at a local scale to find the cause of Korean fir decline and present sustainable management and conservation. Moreover, it is necessary to extend our study subjects to ecosystem ecology and systems ecology to integrate the results from various study subjects for a comprehensive understanding of the reason for Korean fir declines. The results of comprehensive studies could provide clearer answers for Korean fir's declines and the alternatives of conservation management and practices.

• Food Science and Preservation
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• v.23 no.2
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• pp.145-154
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• 2016

This study investigated the possibility of usage of freeze-dried ingredients for the preparation of Nabak kimchi. The quality characteristics of Nabak kimchi using freeze-dried ingredients (radish, kimchi cabbage, green onion, garlic and ginger) were monitored during storage at $4^{\circ}C$. The initial pH of Nabak kimchi was 5.76~5.93, however, it decreased significantly over increasing storage periods (p<0.05). The titratable acidity of Nabak kimchi increased during storage, reaching 0.43~1.08%. Among the freeze-dried samples, those treated with freeze-dried radish and minor ingredients showed lower titratable acidity than that of the control. The initial number of total aerobic and lactic acid bacteria were 5.57~6.25, and 5.52~6.24 log CFU/g, respectively. After 28 days, the population of total aerobic and lactic acid bacteria in the raw ingredients and freeze-dried minor ingredients was less than 8.0 log CFU/g, but more than 9.0 log CFU/g in other samples. Yeasts and molds in Nabak kimchi were detected up to 2~3 log CFU/g, but coliforms were not detected in all samples during storage. The score of firmness and overall acceptability in the control, raw ingredients and freeze-dried minor ingredients were significantly higher than others (p<0.05). These results indicated that freeze-dried ingredients, such as green onion, garlic, and ginger, can be used in kimchi and would delay microbial growth and extend the shelf-life of kimchi without any deduction of sensory quality.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.70-75
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• 1986

The population and kinds of algae causing the waterbloom on the rice seedling bed and the damage of young rice plant by the nuisance green phytoplanktonic algae in rice field were studied to find out the efficiency of fertilizers and the effect of methods of fertilizers application in the rice field, laboratory, pot and green house. pot and green house. The results obtained were summarized as follows; 1. In the rice seedling bed, the kinds of algae causing waterblooms were identified mainly photosynthetic bluegreen algae as the Anabaena, Ulothrix and Oscillatoria spp. in reclaimed saline soil. Micromonospora, Oscillatoria, and Chlamydomonas spp. were habitated mainly in plain. Whereas, Spyrogyra, Oscillatoria and Navicula spp. were identified mainly in mauntainous area. 2. In the rice field, the nuisance phytoplanktonic green algae were identified mainly Scenedesmus, Chlamidospora, and Micromonospora spp. in Gimjae plain, in Namweon mountainous area and Gangjin costal plain, respectively. 3. The algal biomass has been havily habitated in which rice field were constituted with high pH value and high concentration of $NH^+_4-N$ and $NO^-_3-N$ in surface water and in soil with the optimum temperature for the algal growth ($22-30^{\circ}C$). 4. In the laboratory experiment, maximum algal biomass were obtained at levels of 80 ppm for the nitrogen and 20 ppm for the phosphorus. And were obtained of the levels of 40 ppm in the case of joint application of N and $P_2O_5$. 5. From the pot experiment, compare of the control plot, an addition of nitrogen alone or nitrogen+phosphorus enhanced algal biomass while the phosphorus alone did not. 6. Surface application of fertilizer was remarkably increased of algal biomass than did the whole layer or deep layer application.