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

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.9
• /
• pp.1133-1138
• /
• 2006

Smilax china root has been used as traditional medicinal remedy in China and Korea and reported to have various biological activities such as anti-inflammatory, antimutagenic and antimicrobial activities. In this study, the possibility of development as natural antioxidants of Smilax china root extracts was investigated. For the evaluation of antioxidant activity, aqueous- and 25% EtOH extract from Smilax china root were prepared and six different evaluation assay methods, i.e., measurement of total phenolics, radical scavenging effects on 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide (NO) and nitrite $(NO_2)$, reducing power, and inhibitory effect on tyrosinase activity, were used. The total phenolics content of two extracts was high as the level of 36 mg of gallic acid equivalent per 1 g of dried sample tested. The radical scavenging activities of ethanol extract toward DPPH and NO were better than those of aqueous extract (p<0.05). The $NO_2$ scavenging activity of both extracts showed the highest value at pH 1.2 (98%). Especially, the $NO_2$ scavenging activities of EtOH extract were significantly stronger than those of aqueous one at pH 4.2 (51%) and pH 6.0 (32%), respectively. In the reducing power test, both extracts revealed higher ferric ion reducing activity than known antioxidant, vitamin C at the level of $0.05\sim0.1mg/mL$ (p<0.01). The 1 mL of aqueous and 25% EtOH extract showed effective inhibition activity on tyrosinase activity as 45% and 53%, respectively. Therefore, these results suggest that two extracts from Smilax china root may serve as useful natural antioxidants.

• Korean Journal of Social Welfare Studies
• /
• v.48 no.3
• /
• pp.171-208
• /
• 2017

The purpose of this study is to classify the underlying and parsimonious types of child maltreatment and examine whether the effects of risk factors on child maltreatment recurrence differ by type of maltreatment. We utilized the multiyear national administrative data from the National Child Maltreatment Information System collected by Child Protection Agency in Korea. Of 26,921 child maltreatment victims reported and substantiated on or after January 1, 2012, 1,447 children who had recurrence of child maltreatment until December 31, 2015 were selected as maltreatment recurrence group and 4,580 children who had not experienced maltreatment since first substantiation were assigned as maltreatment non-recurrence group. Latent class analysis(LCA) and latent transition analysis(LTA) were used to group children with similar maltreatment subtypes into discrete classes of child maltreatment recurrence. Logistic regression is employed to examine the association between the child maltreatment predominant types and risk factors for recurrence. Results of LCA and LTA showed four latent classes representing predominant type of child maltreatment: 'physical abuse predominant type', 'emotional abuse predominant type', 'sexual abuse predominant type', and 'neglect type'. Significant differences in the effect of risk factors among latent classes were found in child's age and gender, perpetrator's gender, family poverty, biological parent as the perpetrator, domestic violence toward partner, perpetrator's alcoholic problem, insufficient parenting skills, and out-of-home care service, Based on these findings, results suggested how the typology can be used to guide decision about who to target in prevention and intervention programs, and which features of risk factors to target. Practice and policy implications as well as further research tasks were discussed in the lights of searching for useful and important strategies to prevent recurrence of child maltreatment.

• Journal of Korea Water Resources Association
• /
• v.52 no.11
• /
• pp.917-929
• /
• 2019

Denitrification in streams is of great importance because it is essential for amelioration of water quality and accurate estimation of $N_2O$ budgets. Denitrification is a major biological source or sink of $N_2O$, an important greenhouse gas, which is a multi-step respiratory process that converts nitrate ($NO_3{^-}$) to gaseous forms of nitrogen ($N_2$ or $N_2O$). In aquatic ecosystems, the complex interactions of water flooding condition, substrate supply, hydrodynamic and biogeochemical properties modulate the extent of multi-step reactions required for $N_2O$ flux. Although water flow in streambed and residence time affect reaction output, effects of a complex interaction of hydrodynamic, geomorphology and biogeochemical controls on the magnitude of denitrification in streams are still illusive. In this work, we built a two-dimensional water flow channel and measured $N_2O$ flux from channel sediment with different bed geomorphology by using static closed chambers. Two independent experiments were conducted with identical flume and geomorphology but sediment with differences in dissolved organic carbon (DOC). The experiment flume was a circulation channel through which the effluent flows back, and the size of it was $37m{\times}1.2m{\times}1m$. Five days before the experiment began, urea fertilizer (46% N) was added to sediment with the rate of $0.5kg\;N/m^2$. A sand dune (1 m length and 0.15 m height) was made at the middle of channel to simulate variations in microtopography. In high- DOC experiment, $N_2O$ flux increases in the direction of flow, while the highest flux ($14.6{\pm}8.40{\mu}g\;N_2O-N/m^2\;hr$) was measured in the slope on the back side of the sand dune. followed by decreases afterward. In contrast, low DOC sediment did not show the geomorphological variations. We found that even though topographic variation influenced $N_2O$ flux and chemical properties, this effect is highly constrained by carbon availability.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.12
• /
• pp.1234-1268
• /
• 2004

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2002 and 2003 has been carried out. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment/design. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation in diverse facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat transfer, humidity was also interesting to promote comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing research topics. Well developed CFD technologies were widely applied for analysis and design of various facilities and their systems. (2) Heat transfer characteristics of enhanced finned tube heat exchangers and heat sinks were extensively investigated. Experimental studies on the boiling heat transfer, vortex generators, fluidized bed heat exchangers, and frosting and defrosting characteristics were also conducted. In addition, the numerical simulations on various heat exchangers were performed and reported to show heat transfer characteristics and performance of the heat exchanger. (3) A review of the recent studies shows that the performance analysis of heat pump have been made by various simulations and experiments. Progresses have been made specifically on the multi-type heat pump systems and other heat pump systems in which exhaust energy is utilized. The performance characteristics of heat pipe have been studied numerically and experimentally, which proves the validity of the developed simulation programs. The effect of various factors on the heat pipe performance has also been examined. Studies of the ice storage system have been focused on the operational characteristics of the system and on the basics of thermal storage materials. Researches into the phase change have been carried out steadily. Several papers deal with the cycle analysis of a few thermodynamic systems which are very useful in the field of air-conditioning and refrigeration. (4) Recent studies on refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement when new alternative refrigerants are applied. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and new alternative refrigerants including natural refrigerants. Efficiency of various compressors and performance of new expansion devices are also dealt with for better design of refrigeration/air conditioning system. In addition to the studies related with thermophysical properties of refrigerant mixtures, studies on new refrigerants are also carried out. It should be noted that the researches on two-phase flow are constantly carried out. (5) A review of the recent studies on absorption refrigeration system indicates that heat and mass transfer enhancement is the key factor in improving the system performance. Various experiments have been carried out and diverse simulation models have been presented. Study on the small scale absorption refrigeration system draws a new attention. Cooling tower was also the research object in the respect of enhancement its efficiency, and performance analysis and optimization was carried out. (6) Based on a review of recent studies on indoor thermal environment and building service systems, it is noticed that research issues have mainly focused on several innovative systems such as personal environmental modules, air-barrier type perimeterless system with UFAC, radiant floor cooling system, etc. New approaches are highlighted for improving indoor environmental conditions and minimizing energy consumption, various activities of building energy management and cost-benefit analysis for economic evaluation.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.6
• /
• pp.970-976
• /
• 2011

Strip tiller equipment was developed to reduce soil erosion in the slope land for highland agricultural area. The equipment consisted of 4 rows strip tillage device and fertilizer applicator. The field was tilled in 10 cm width and in 10 cm depth by the equipment, of which tilled surface was 16.7% of full-width tillage. The working time and fuel consumption of the equipment were $3.8hours\;ha^{-1}$ and $24.4L\;ha^{-1}$ respectively, which were 59% and 74% less than those of the conventional tillage. Fertilizer efficiency of the equipment in cultivation of Chinese cabbage was 1.7, 1.6 and 1.5 times higher in nitrate, phosphorous and potassium respectively, than conventional tillage. When the equipment was used after covering of rye residue, the quantity of runoff was 49~67% lower than the conventional tillage. And the quantity of soil loss were 1.3 and $0.2Mg\;ha^{-1}$ at right after and 30 days after planting of Chinese cabbage respectively, while 11.5 and $4.1Mg\;ha^{-1}$ in conventional tillage. In conclusion, the strip tillage equipment developed in this study can be applicable to slope land, so that soil loss of 90% can be reduced.

• Journal of Life Science
• /
• v.31 no.9
• /
• pp.818-826
• /
• 2021

5-Aminolevulinic acid phosphate (5-ALA-p) is a substance obtained by eluting 5-ALA (a natural delta amino acid) with aqueous ammonia, adding phosphoric acid to the eluate, and then adding acetone to confer properties suitable for use in photodynamic therapy applications. However, its pharmacological efficacy, including potential mechanisms of antioxidant and anti-inflammatory reactions, remains unclear. This study aimed to investigate the effects of 5-ALA-p on oxidative and inflammatory stresses in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Our data showed that 5-ALA-p significantly inhibited excessive phagocytic activity via LPS and attenuated oxidative stress in LPS-treated RAW 264.7 cells. Furthermore, 5-ALA-p improved mitochondrial biogenesis reduced by LPS, suggesting that 5-ALA-p restores mitochondrial damage caused by LPS. Additionally, 5-ALA-p significantly suppressed the release of nitric oxide (NO) and pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and IL-6, which are associated with the inhibition of inducible NO synthase and respective cytokine expression. Furthermore, 5-ALA-p reduced the nuclear translocation of nuclear factor-kappa B (NF-κB) and inhibited phosphorylation of mitogen-activated protein kinases (MAPKs), indicating that the anti-inflammatory effect of 5-ALA-p is mediated through the suppression of NF-κB and MAPK signaling pathways. Based on these results, 5-ALA-p may serve as a potential candidate to reduce inflammation and oxidative stress.

• Anatomy & Biological Anthropology
• /
• v.31 no.4
• /
• pp.133-142
• /
• 2018

3D histology is a imaging system for the 3D structural information of cells or tissues. The synchrotron radiation propagation phase contrast micro-CT has been used in 3D imaging methods. However, the simple phase contrast micro-CT did not give sufficient micro-structural information when the specimen contains soft elements, as is the case with many biomedical tissue samples. The purpose of this study is to develop a new technique to enhance the phase contrast effect for soft tissue imaging. Experiments were performed at the imaging beam lines of Pohang Accelerator Laboratory (PAL). The biomedical tissue samples under frozen state was mounted on a computer-controlled precision stage and rotated in $0.18^{\circ}$ increments through $180^{\circ}$. An X-ray shadow of a specimen was converted into a visual image on the surface of a CdWO4 scintillator that was magnified using a microscopic objective lens(X5 or X20) before being captured with a digital CCD camera. 3-dimensional volume images of the specimen were obtained by applying a filtered back-projection algorithm to the projection images using a software package OCTOPUS. Surface reconstruction and volume segmentation and rendering were performed were performed using Amira software. In this study, We found that synchrotron phase contrast imaging of frozen tissue samples has higher contrast power for soft tissue than that of non-frozen samples. In conclusion, synchrotron radiation propagation phase contrast cryo-microCT imaging offers a promising tool for non-destructive high resolution 3D histology.

• Journal of Life Science
• /
• v.29 no.3
• /
• pp.337-344
• /
• 2019

The free radical scavenging, cytotoxic effects, and flavonoid content of fractions from Lycopus lucidus Turcz leaves were here investigated. The flavonoid contents of 85% methanol (MeOH) and n-butanol (BuOH) fractions of the leaves were 41.5 mg/g and 77.2 mg/g, respectively. In DPPH and ABTs+ assays, 85% MeOH and n-BuOH fractions from the L. lucidus Turcz leaves had a greater scavenging effect (p<0.05). The n-BuOH fraction (0.5 mg/ml concentration) had scavenging effects of 88% and 92% in the DPPH and ABTs+ assays, respectively (p<0.05). Cell viability tests showed that treatment with L. lucidus Turcz leaf fractions caused cytotoxicity in the growth of AGS, HT-29, and HT-1080 cancer cells. Of the different fractions, the 85% MeOH sample displayed the highest cytotoxic activity; the $IC_{50}$ values of this fraction against AGS, HT-1080, and HT-29 cancer cells were 0.03 mg/ml, 0.14 mg/ml, and 0.16 mg/ml, respectively. These biological results indicate that the n-BuOH fraction was more effective in anti-oxidant activity while the 85% MeOH fraction was stronger in cytotoxic effects, and they suggest that these two fractions from L. lucidus Turcz leaves may contain valuable bioactive compounds, such as flavonoids.

• Journal of Wetlands Research
• /
• v.20 no.4
• /
• pp.363-369
• /
• 2018

One of the recent environmental problems is climate change due to the increase of atmospheric $CO_2$, which causes ecological changes and various environmental problems. Therefore, various studies are being carried out to reduce $CO_2$ in the world in order to solve various environmental problems caused by increase of $CO_2$. The $CO_2$ reduction using microalgae is an environmentally friendly method by using photosynthesis reaction of microalgae. However, most studies using single species. There is no study on the $CO_2$ fixing efficiency of microalgae in natural rivers. Therefore, this study was to identify the microalgae in the Sum river and to analyze the growth characteristics of microalgae in the river to obtain optimal culture conditions. And the changes of biomass and chlorophyll-a of microalgae were analyzed according to $CO_2$ concentration and injection rate. The purpose of this study was to investigate the fixing efficiency of carbon dioxide in microalgae in natural rivers. Six kinds of dominant species were observed as a result of the identification of microalgae in Sum river(Ankistrodesmus falcatus, Scenedesmus intermedius, Selenodictyum sp., Xanthidium apiculatum var. laeve, Cosmarium pseudoquinarium, Dictyosphaerium pulchellum). All of these species were green algae. Biomass and chlorophyll-a increased with the increase of $CO_2$ concentration and biomass and chlorophyll-a increased faster flow rate at the same $CO_2$ concentration. Also, the quantity of $CO_2$ fixation on the microalgae tended to be higher when the flow rate of injected gas was faster. This study can be referred as being significant in the micro-algae in river. In addition, the optimal conditions for $CO_2$ fixation of microalgae in rivers and the quantification of the quantity of $CO_2$ fixation from microalgae in rivers can be used as basic data for future policy of $CO_2$ reduction.