• Journal of the Korean Geographical Society
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• v.40 no.4 s.109
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• pp.416-427
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• 2005

This paper aims to investigate morphological changes of deltaic barrier islands in the Nakdong Estuary and especially their spatial variations after barrage construction. We analyzed shorelines, geometrical centroids, and areas to reveal the changes of barrier islands. Here, we suggest three interesting points from this study. First, each individual barrier island in the Nakdong estuary goes through a different stage of the geomorphic cycle. The frontal barrier islands such as Sinja-do and Doyo-deung grow because they are located in front of the gates of the barrage. Sediments in water out of the gates are moved to offshore and then reworked by coastal processes such as waves and tides. Second, on the contrary, Baekhap-deung located behind Doyo-deung now diminishes indicating that sediments mainly move to the frontal growing island. Third, there is no morphological change in several barrier islands far away from the main flow of the Nakdong river such as Jinwoo-do, Daema-deung, and Jangja-do. In conclusion, barrier islands in the Nakdong estuary show distinct spatial variations. As a barrier island is closer to the main channel or is in the frontal location, there happens a very dynamic change in the morphology of the island.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.2
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• pp.174-183
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• 2001

During the rapid phase of gonadal development of the freshwater teleost, the catfish (Silurus asotus), the influence of hCG upon the inducement of final oocyte maturation and spawning was investigated electrophoretically and ultrastructurally. The electrophoretic patterns obtained were different in the presence and absence of some of the major or minor zones, because of the hormone level in catfish. The vitellogenin of hormone-treated fish was stained more intensively than that of sham-treated fish. These proteins showed some minor or main bands of egg extracts which migrated at positions corresponding to molecular weights of approximately 90,000. However, the thickness of electrophoretic band in molecular weight for hCG-treated fish was slightly lower than that for saline control. It seemed the plasma protein with molecular weight of approximately 45,000 in hCG-treated fish disappeared. In contrast to the control fish, the ovaries in the catfish treated with hCG shows a marked ultrastructural change under the electron microscope. No dilated profiles were seen in the granulosa cells of the mature oocyte before ovulation. After germinal vesicle breakdown (GVBD), the zona radiata interna (ZRI) becomes more compact, and there is a loss of all the processes from the pore canals. There is a wide space between the vitelline membrane and zona radiata. Also, during final maturation, the microvillar processes from the oocyte are seen no longer to penetrate deeply into the extracellular spaces of the overlying granulosa cells, and the reticulate patterns of the zona radiata interna becomes occluded, giving the zona radiata a more solid appearance. It has been possible to initiate 100% oocyte maturation in yolk granules and follicles in vivo by treatment with hCG and a high water temperature ($27^{\circ}C$). In hCG-treated fish, the percentages of successful artificial fertilization and hatching were maximal at 15 h after a single injection. It seems clear that a long acting preparation containing hCG can be successfully used in prespawning fish to advance the final events of gonadal maturation and initiate spawning. Further studies are necessary to evaluate the potential of hCG to either stimulate or inhibit the reproductive development of fish at other stages of the seasonal reproductive cycle.

• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.78-84
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• 2015

The purpose of this study is to evaluate the removal efficiency of phosphorus from synthetic waste water by reduction and oxidation reaction of Cu-Zn metal alloy. Cu-Zn metal alloy applied in this study is composed of 40% of Zn and 60% of Cu, which is so called Muntz metal. And the fibrous type of metal alloy has approximately $200{\mu}m$ of thickness. Metal is oxidized in an aqueous solution to generate electron and metal ion. The mechanism of phosphate treatment is co-precipitation of metal ion and phosphorous ion at various pH and temperature. The treatment efficiency showed the maximum at a one cycle treatment. This result means that the surface area of reaction material is sufficient enough to get reaction equilibrium. Experiment is conducted at various pH from 5 to 9, and showed the maximum efficiency at pH 8. Phosphorous is dominated as a type of $H_2PO_4{^-}$ and $HPO_4{^{2-}}$ at this pH condition. We could not consider the temperature effect independently, because phosphorous removal efficiency showed such a complex mechanism. We could get high efficiency at lower temperature in this research.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.8-14
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• 2017

Improvements in the standard of living and lifestyle have led to increased sales of frozen milk products, such as soft ice cream or slush. These frozen milk products are commonly made in a small refrigeration machine. In a soft ice cream machine, the freezer is composed of a concentric cylinder, where the refrigerant flows in the annul us and the ice cream is made in the cylinder by a rotating scraper. In this study, an optimization and performance evaluation were conducted on a soft ice cream machine having a freezer volume of 2.8 liters. The optimization was focused on the scraper rotation speed and the refrigerant path of the freezer. The measurements included the temperature, pressure and consumed power. At the optimized speed of 124 rpm, ice cream was produced in 6 minutes and 2 seconds, and the COP was 0.90. Through a flow visualization study using air-water, the refrigerant path was improved. The improved design reduced the ice cream making time significantly. The present results may be used for the optimization of other refrigeration cycles, including those of frozen food products.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1285-1292
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• 2011

The characteristics of a semiconductor chiller system with EEV have been experimentally studied. Three experiments on temperature changes (increase and decrease), load variation, and control precision were conducted to investigate the operating characteristics of the semiconductor chiller. The power consumption was 8.9 kW during increase in temperature. The required time was 37.5 min for CH1 and 39.5 min for CH2. Moreover, the time required for falling temperature was 26.5 min. The control precision for partial load operation was relatively low compared to that of a full load operation. In addition, the CH2 equipped with a step motor showed better control precision. The power consumed by the chiller for process cooling water was 1.8 kW, which was one-half of that consumed during the refrigeration cycle. The objective of this study is to provide an optimal control guideline for the semiconductor chiller design.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.461-464
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• 2002

A Chemoautotroph identified as an Aeromonas sp. strain JS-1 was isolated from fresh water. Aeromonas sp. strain JS-1 used the $H_2$ and $CO_2$ as energy and carbon sources, respectively. Growth characteristics for improving the $CO_2$ fixation rate were examined in batch cultivation. Its results shown that the optimal growth appeared at culture conditions of $35^{\circ}C$, pH 7 and NaCl 0.1%(w/v). Some hydrogen-oxidizing bacteria were reported that the enzyme activity of ribulose 1,5-bisphosphate carboxylase- oxygenase (RubisCO-EC 4.1.1.39), in the key enzyme of the Calvin-Benson cycle. A RubisCO was purified from a chemoautotrophic bacterium, Aeromonas sp. strain JS-1. the enzyme was purified by ammonium sulfate precipitation, DEAE-sepharose CL-6B and gel filtration chromatography. The RubisCO showed that molecular mass was about 560KDa from gel filtration chromatography and nondenaturing PAGE, and the RubisCO was confirmed to consist of $L_8S_8$ enzyme structure by sodium dodecyl sulfate polyacrylamide gel electrophoresis. A large subunit was about 56KDa and small one was about 15kDa. The Km values of the enzyme for ribulose 1,5-bisphosphate(RUBP), $NaH^{14}CO_3$, and $Mg^{++}$ were estimated to be 0.25mM, 5.2mM, and 0.91mM, respectively. The optimum temperature for RubisCO enzymatic activity were $50^{\circ}C$, and the enzymatic activity was stable up to $45^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.679-686
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• 2010

To investigate the contribution of macroalgae to biogeochemical nutrients and carbon cycles, we measured the uptake rates of nutrients and $CO_2$ by Undaria pinnatifida using an incubation method in an acrylic chamber. From January to March 2010, U. pinnatifida was sampled at Ilkwang, a well-known area of macroalgae culture in Korea. The initial and final concentrations of nutrients, dissolved oxygen, total alkalinity, and pH of the chamber water were measured, and production/uptake rates were calculated using concentration changes, chamber volume, and incubation time. The production rate of dissolved oxygen by U. pinnatifida (n = 32) was about $5.4{\pm}4.0\;{\mu}mol\;g_{fw}^{-1\;}h^{-1}$. The uptake rate of total dissolved inorganic carbon (TDIC), calculated by total alkalinity and pH, was $7.9{\pm}6.5\;{\mu}mol\;g_{fw}^{-1}\;h^{-1}$. Nutrients uptake averaged $141.7{\pm}119.2$ nmol N $g_{fw}^{-1}\;h^{-1}$ and $15.0{\pm}9.1$ nmol P $g_{fw}^{-1}\;h^{-1}$. A positive linear correlation ($r^2$ = 9.6) existed between the production rate of dissolved oxygen and the uptake rate of total dissolved inorganic carbon, suggesting that these two factors serve as good indicators of U. pinnatifida photosynthesis. The relationships between fresh weight and uptake rates of nutrients and $CO_2$ suggested that younger specimens (<~50 g fresh weight) are much more efficient at nutrients and $CO_2$ uptake than are specimens >50 g. The amount of carbon uptake by the total biomass of U. pinnatifida in Korea during the year of 2008 was about 0.001-0.002% of global ocean carbon uptake. Thus, more research should be focused on macroalgae-based biogeochemical cycles to evaluate the roles and contributions of macroalgae to the global carbon cycle.

• Journal of Biosystems Engineering
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• v.35 no.2
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• pp.100-107
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• 2010

This study was conducted to investigate the effects of electric current stimuli and high-voltage electric field treatments on brown rice germination. The brown rice stimulated by electrical current stimuli, functional electrical stimuli of a pulse type, and high-voltage electric field treatments were observed (Type I, II and III). Treatment Type I was a method of semi-soaking brown rice with electric current stimuli of 0.13 V/cm, 0.19 V/cm, and 0.25 V/cm into Petri-dishes for 72 hours. Type II was a method of semi-soaking brown rice with functional electrical stimuli of a pulse type(DC 1 V, 1 Hz, 5%, and duty cycles of 5%, 20%, and 35%) into Petri-dishes for 72 hours. Type III was a method of water-soaking with high-voltage electric field treatments for 60 hours. High-voltage electric field treatments at 15 kV/cm were also conducted for 2.5 min, 7.5 min, and 10 min, respectively. The germination rate and the sprout growth of brown rice germinated by electric current stimuli with 0.13 V/cm, 0.19 V/cm, and 0.25 V/cm were increased by about 10-15% compared with those of the control group. The germination rate and the sprout growth of brown rice germinated by functional electrical stimuli of pulse type(DC 1 V, 1 Hz, 5% duty cycle) were increased by about 10∼15% compared to those of the control group. Also, the best effective treatment among high-voltage electric field treatments was the 10 min group at 15 kV/cm. The germination rate and the sprout growth of brown rice germinated by this treatment of 10 min at 15 kV/cm were increased by about 10∼20% compared to those of the control group. The treatments of electric current stimuli and high-voltage electric field accelerated the germination rate and sprout growth of brown rice by about 10∼15% compared to those of the control group.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.111-120
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• 2014

The aim of this study is to develop an integrated urea-SCR catalytic filter system for reducing soot and $NO_X$ emissions simultaneously in diesel engines. In this study, the characteristics of exhaust emissions relative to reactive activation temperature under four kinds of engine loads are experimentally investigated by using a four-cycle, four-cylinder, direct injection type, water-cooled turbo intercooler ECU common-rail diesel engine with the integrated urea-SCR $MnO_2-V_2O_5-WO_3/TiO_2/SiC$ catalytic filter system operating at three kinds of engine speeds. The urea-SCR reactor is used to reduce $NO_X$ emissions, and the catalytic filter system is used to reduce soot emissions. The reactive activation temperature is very important for reacting a reducing agent with exhaust emissions. The reactive activation temperatures in this experiment is applied to 523, 573 and 623 K. The fuel is sprayed by the pilot and main injections at the variable injection timing between BTDC $15^{\circ}$ and ATDC $1^{\circ}$ according to experimental conditions. It is found that the $NO_X$ conversion rate is the highest as 83.9% at the reactive activation temperature of 523 K in all experimental conditions of engine speed and load, and the soot emissions shown by the average reduction rate of approximately 93.3% are almost decreased below 0.6% in all experimental conditions regardless of reactive activation temperatures. Also, the THC and CO emissions by oxidation reaction of Mn, V and Ti are shown in the average reduction rates of 70.3% and 38% regardless of all experimental conditions.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.645-661
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• 2009

The water extract of Dohongsamul-Tang(DHSMT) has been traditionally used to stroke and brain injuries in Oriental Medicine. The present study was designed to investigate the effects of DHSMT on the gene expression profile of cerebral infarction by cDNA microarray in photothrombotic ischemia mouse model. Photothrombotic ischemia was induced in stereotactically held male BALB/c mice using rose bengal and cold light. MRI was performed 24 hours after inducing photothrombosis using 1.5 T MRI and 47 mm surface coil to obtain T2-weighted, and contrast-enhanced images. After MRI test, animal was sacrificed and the brain sections were stained for hematoxylin and eosin and immunohistochemistry. MRI and histological analysis revealed that lesion of thrombotic ischemia was well induced in the cortex with the evidence of biological courses of infarction. The target area of thrombotic infarction was 1 mm anterior to bregma and 3 mm lateral to midline with 2 mm in diameter, which were decreased by administration of DHSMT. To assess gene expression pattern of cerebral infarction, mRNA was isolated and reacted with microarray chip(Agilant's DNA Microarray 44K). Scatter and MA plot analysis were performed to clustering of each functional genes. M value [M=log2(R/G), A={log2(R ${\times}$ G)}/2] was between -0.5 and +0.5 with 40% difference. After pretreatment with DHSMT, the expression levels of mRNA of many genes involved in various signaling pathway such as apoptosis, cell cycle, cell proliferation, response to oxidative stress, immune response, angiogenesis, and inflammatory cytokine were markedly inhibited in photothrombotic ischemia lesion compared to the control group. These results suggest that DHSMT prevent ischemic death of brain on photothrombotic ischemia model of mice through modulation of gene expression at the transcriptional level.