• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.295-303
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• 2000

The water clarification efficiency was examined in a shallow wetland where dense vegetation was formed naturally in an abandoned paddy field. And, also two enclosure experiments were carried out to measure the effects of materials exchange between sediment and the overlying water with the existence of vegetation and accumulated litter. The hydraulic retention time of wetland was regulated in 1.2 day. The removal rates of SS (56%) and $NO_3-N$ (61%) were high, considering its short retention time. However, removal efficiencies of VSS (28%), COD (14%), DOC (1%),and TP (0.2%) were relatively lower. This low removal efficiencies were thought to be due to the release of dissolved form of organic matter and phosphorus from the sediment. Most of constituents except nitrate were higher in the enclosure at the beginning of enclosure installation than that of the outflowing water from wetland. And then, it has fluctuated and decreased with time. The wetland was in equilibrium state of settling, accumulation of organic debris, and regeneration of dissolved material from sediment. So ultimately high primary production by dense vegetation in the wetland may be the reason of unfavorable or low treatment efficiency of wetland after many years of operation for wastewater treatment. However, the water quality of effluent from the wetland showed smaller variation and better condition than that of inflow, especially during storm events. It can be concluded that this wetland is suitable for the improvement of water quality from nonpoint sources.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.364-373
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• 2009

We evaluated stream health, based on integrative approaches of qualitative habitat evaluation index (QHEI), chemical water quality and the index of biological integrity (IBI) using fish assemblages in Daejeon Stream during August 2004 - October 2007. The QHEI values in this study averaged 78.2 (n=28, range: 47$\sim$124), indicating "fair" condition based on the criteria of US EPA (1993). The highest value was in the headwater site (S1) that was 112 (good), whereas the value in S3, mid and downstream was SS (fair-poor) that was the lowest owing to a disturbance on the bed and an artificial bank. Concentrations of chemical parameters such as BOD, TP and conductivity increased from the upstream to the downstream due to higher inputs of organic matters and nutrients from the urban area. Conductivity and TP showed a dilution of stream water by rainwater during summer monsoon. Analysis of fish compositions showed that total number of species was 24 and Zacco platypus was predominated (82%). The mean IBI was 17 (range: 12$\sim$30) during four years and the IBI values also decreased from S1 to S4. These results indicated that ecological health was degradated distinctly as the stream goes down through the city-center. We concluded that Daejeon Stream running through the city are influenced by chemical impact such as an influx of domestic sewage as well as the quality of habitat.

• Korean Journal of Ecology and Environment
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• v.46 no.3
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• pp.395-408
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• 2013

Environmental condition can induce changes in early life-history traits in order to maximise the ecological fitness. Here I investigated how temperature change and variation in human aquatic activity/behaviour affect early life-history consequences in fish using a dynamic-state-dependent model. In this study, I developed a general fish's life-history model including three life-history states depend-ing on foraging activity, such as body mass, mass of reproductive tissue (i.e., gonadal development) and accumulated stress (i.e., cellular or physiological damage). I assumed the level of foraging activity maximises reproductive success-ultimately, fitness. The model predicts that growth rate, development of reproductive tissues and damage accumulation are greater in higher temperature whereas higher human aquatic activity rapidly reduced the growth rate and development of reproductive tissue and increased damage accumulation. While higher foraging activity in higher temperature is less affected by human aquatic activity, the foraging activity in lower temperature rapidly declined with human aquatic activity. Moreover, lower survival rate in higher temperature or human aquatic activity was independent on mortality rate due to human aquatic activity or mortality rate when foraging activity, respectively. However, the survival rate in lower temperature or human aquatic activity was dependent on these mortality rates. My findings suggest that including of early life-history traits in relation to climate-change and human aquatic activity on the analysis may improve conservation plan and health assessment in aquatic ecosystem.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.41-61
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• 1985

The purse-seine fishery is very important in the coastal fishery of Korea and the main fish species of this fishery are mackerals and also the main fishing grounds are Tushima Current region, To investigate the relationship between the fishing grounds of mackerels and oceanographic condition, the distribution of mean catches of mackerals of each size (1974~1982) was firstly examined and the oceanographic observation carried out in eastern and western area of Cheju island, being main fishing grounds, in July and October, 1983. The results are as follows: The main fishing grounds of mackerals were also in the Tsushima Current region in southern sea of Korea and the season of the good catches are in May and September to October. The small and medium size of mackerals of which the body lengths are 27 cm to 31 cm, about 2-3 ages, occupied about 90% but the smaller size mackerals of which body lenth is 22 cm (1 age)were about 40 to 70% in February to March. The locations of seasonal fishing grounds could founded by 15$^{\circ}C$ isotherm which indicates the Tsushima Current Water. With trace of this isotherm it was founded that the fishing grounds near the Korean Strait than that of south of Cheju island moves faster northward and/or later southward. The main fishing grounds eastward and westward of Cheju island were the front areas formed between the Tsushima Current Water and the southern coastal water of Korea or Yellow Sea Bottom Cold Water. And also the distributions of transparences, water colors and the penetration of sun light of this fishing grounds were similar to that of the temperature, the salinity or volume of planktonic organism.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.471-475
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• 2017

This study aims to suggest the methodology to improve to estimate back-calculated fish growth parameters using weighted average. It is to contribute to correct errors in the calculation of back-calculated growth equation with unequal numbers of sample by age. If the numbers of sample were evenly collected by age, each back-calculated length at age was equal between arithmetic and weighted averages. However, most samples cannot be evenly collected by age in reality because of different catchability by fishing gear and limitation of environment condition. Therefore, the estimation of back-calculated length by weighted average method is essential to calculate growth parameters. There were some published growth equations from back-calculated length using a simple arithmetic average with different numbers of samples by age when searching for back-calculated growth equations from 91 relevant papers. In this study, the process of deriving growth equation was investigated and two different average calculations were applied to a fish growth equation, for example of Acheilognathus signifer. Growth parameters, such as $L_{\infty}$, k and $t_0$, were estimated from two different back-calculated averages and the growth equations were compared with growth performance index. Based on the correction of back-calculated length using weighted average by age, the changes by female and male were -14.19% and -5.23% for $L_{\infty}$, and 59.28% and 18.91% for k, respectively. The corrected growth performance index by weighted average improved at 7.05% and 2.46% by female and male, respectively, compared to the arithmetic averages.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.4
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• pp.295-303
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• 2012

Based on the data observed and analyzed on a groundwater flow system in the KURT (KAERI Underground Research Tunnel) site, the transport of radionuclides, which were assumed to be released at the supposed position, was calculated on the time-domain. A groundwater pathway from the release position to the surface was identified by simulating the groundwater flow model with the hydrogeological characteristics measured from the field tests in the KURT site. The elapsed time when the radionuclides moved through the pathway is evaluated using TDRW (Time Domain Random Walk) method for simulating the transport on the time-domain. Some retention mechanisms, such as radioactive decay, equilibrium sorption, and matrix diffusion, as well as the advection-dispersion were selected as the factors to influence on the elapsed time. From the simulation results, the effects of the sorption and matrix diffusion, determined by the properties of the radionuclides and underground media, on the transport of the radionuclides were analyzed and a decay chain of the radionuclides was also examined. The radionuclide ratio of the mass discharge into the surface environment to the mass released from the supposed repository did not exceed $10^{-3}$, and it decreased when the matrix diffusion were considered. The method used in this study could be used in preparing the data on radionuclide transport for a safety assessment of a geological disposal facility because the method could evaluate the travel time of the radionuclides considering the transport retention mechanism.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.297-303
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• 2011

The existing studies of VDT syndrome have been researched only about for nurse groups without radiological technologists. The target of this study was workers who perform VDT task in general hospital placed in Daejun City such as insurance judgement, patient affairs, medical record management, medical computing service, hospital administration, and radiological sections. This study was conducted at October 15, 2009 to November 2, 2009 using structured questionnaire. Results of group A (age 20-29, less than 5 years experience at clinical site, normal staff, and unmarried group) showed significant skin and psychological conditions among recognition symptoms of VDT syndrome. Group B (age 30-39, 6-10 years experience at clinical site, managing staff, and married group) tends to be similar at orbital, whole body and muscles' frame response among recognition symptoms of VDT syndrome. Results of "Multiple Linear Regression" with dependent variable that is scores of recognition symptoms of VDT syndrome are as follows. The factors which influences for orbital-related problem is gender, health cares and obstacles during daily life. The factors which influences for whole body-related is exercise, stress and recognition for health condition and the factors which influences muscles' frame-related is 6-10 years experience at clinical site, human relationship, health cares and obstacles during daily life. These are proved to be similar by statistic analysis. There is small difference at recognition symptom of VDT syndrome between the radiological technologist and other groups in general hospital. Yet, as the working circumstance of radiological technologist gradually changes to VDT environment, the recognition symptom of VDT syndrome became conscious. This can be prevented by regular job rotation, which will escape the continuous repetition of working pattern.

• Korean Security Journal
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• no.17
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• pp.301-316
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• 2008

The occurrence of complicating, multilateral social condition demands the strategy for facing many social state and consolidating public security against criminal loss. The lacking ability of local police for preventing crime can't satisfy the demand of security and can't get rid of fear of crime. At last, it brings a distrust of public confidence and became a factor of serious social crisis. We have problems - not only making an alternative plan for preventing crime, but also introducing CPTED(Crime Prevention Through Environmental Design) by environmental design, to expect crime prevention and to select systemic crime prevention system and the most suitable model. And we have a goal - to recognize the importance of guard activity for local crime, analyse public safety activity in community & focusing guard activity as a strategy for them, apply CPTED in police and private security company as a local crime prevention & setting effective model, and, make it as an index for preventing & dealing with intellectual, brutal crime. The rapid growth in the guarding-activity field lighten the burden of police for crime-prevention. But the misjudgement of some people blocks it to be settled institutionally. It needs to reconsider what is the effective crime-prevention method, at this point of time when the all parts of a nation changing into unlimited competitive, private self-control system.

• Journal of Plant Biotechnology
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• v.31 no.2
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• pp.133-138
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• 2004

Growth of M.9 (Malus domestica Bark. cv) and M.26 (Malus domestica Bark. cv) of dwarf apple rootstock, cultured on MS agar medium in a vessel with ventilating stopper (VS) and then in vivo rooting and acclimatization under combined-treatment by some materials with IBA, were investigated. Concentration of $CO_2$ and ethylene in the vessel with VS was lower then in the vessel with non-VS. Change of temperature and humidity in the vessel with VS was repeated by light condition. Stomatal pares of tissue in the vessel with VS were immediately closed after plantlets were exposed to room humidity but those in the vessel with non-VS were opened after 20 minutes exposure to room humidity. Leaf area and chloroplast index of tissue in the vessel with VS was higher then in the vessel with non-VS. In vivo rooting ratio and acclimatization ratio of M.9 and M.26 was highest in 300mg/L IBA＋3％ sucrose dip-treatment among other combined- treatments.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.494-503
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• 2015

This study was focused on the comparison of the variations in the yield and chemical composition of Chamaecyparis obtusa leaf oil obtained under different pressure conditions of the supercritical carbon dioxide extraction (SCE), and by hydro-distillation. SCE was carried out varying the pressure in the range of 100~400 bar at $40^{\circ}C$. The chemical composition of C. obtusa leaf oils was determined by gas chromatography-mass spectroscopy (GC-MS) analysis. The maximum yield of 4.4% (relative to the initial mass of oven dry mass) was obtained in the extraction under 300 bar pressure, which was higher than that of the hydro-distillation method (1.9%). The contents of sesquiterpenes in the extracts obtained by the SCE were higher than those of the essential oils of C. obtusa by the hydro-distillation. The sesquiterpenes in the SCE extracts made up approximately 39%~46% of the total, followed by monoterpenes, diterpene, and lignan. The contents of each constituent in the supercritical carbon dioxide extracts were varied on the extraction pressure. Therefore, these results showed that the extraction condition of SCE had significant effect on the yield of C. obtusa oils and its chemical composition.