• Journal of Korean Society of Forest Science
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• v.40 no.1
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• pp.63-69
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• 1978

A bark comprises about 10 to 20 percents of a typical log by volume, and is generally considered as an unwanted residue rather than a potential1y valuable resourses, As the world has been confronted with decreasing forest resources, natural resources pressure dictate that a bark should be a raw material instead of a waste. The utilization of the largely wasted bark of genus Pinus, Quercus, and Populus grown in Korea can be enhanced by learning their chemical properties. However, the chemical study of tree bark grown in korea have never been undertaken. In the present paper, the studies on the chemical properties of bark comprise carbohydrates, lignin, and extractives, composition of reducing sugars and five essential elements. The results may be summarized as follows: 1. Bark are much richer in quantity of lignin and extractives than the corresponding wood, and are chiefly consisted of lignin, extractives and carbohydrates orderly. It is the same with ash contents. Alcohol-benzene extractives of populus bark are the highest among three genus. 2. Although glucose constitutes the major sugar in both pine and hardwoods bark, in pinus, arabinose and xylose are the next but in hard woods, the next is xylose. 3. Essential elements, Ca and Kjeldahl-N are higher in the bark than in the wood. Ca content is the highest among others, and N,K followed it. Essential elements are higher in Quercus than in Populus and pinus.

• Korean Journal of Weed Science
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• v.16 no.1
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• pp.14-20
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• 1996

Growth, nutrient uptake and photosynthesis as affected by submersion of shoot in pickerel weed (Monochoria vaginalis Presl.) were determined. The shoots of pickerel weeds in hydroponic culture were subjected to the submerged or emerged condition at 3- or 5-leaf stage for 8 or 10 days. Under submerged condition, growth in plant height was enhanced, but leaf number, leaf area, fresh and dry weight were reduced compared to those under the emerged condition. Similar responses in growth to submergence were obtained with the pickerel weeds rooted in the soil. Under submergence, chlorophyll content increased during the first 2 days, but thereafter remarkably decreased at 3-leaf stage and after the first 4 days at 5-leaf stage. Compared to the emerged condition, uptakes of $NH_4\;^+$-N, $NO_3\;^-$-N, $P_2O_5$ and $K^+$ were reduced, but uptakes of $Ca^{++}$ and $Mg^{++}$ increased under the submerged condition. Photosynthetic rate of shoot under water, measured by $CO_2$electrode, showed the maximum by 210 ${\mu}$moles $HCO_3\;^-$/g F.W. at the 8th day after submergence(DAS) at 3-leaf stage and 320 ${\mu}$moles $HCO_3\;^-$/g F. W. at 6 DAS at 5-leaf stage. These results indicate that pickerel weeds grow much better when the shoot is air-exposed and are less tolerable to submergence at 3 leaf-stage than at 5-leaf stage.

• Journal of the Mineralogical Society of Korea
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• v.16 no.4
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• pp.333-339
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• 2003

A new mineral, Zn analogue of rancieite (Chimooite), has been discovered at the Dongnam mine, Korea. It occurs as compact subparallel fine­grained flaky or acicular aggregates in the massive manganese oxide ores which were formed by supergene oxidation of rhodochrosite­sulfide ores in the hydrothermal veins trending NS­N25E and cutting the Pungchon limestone of the Cambrian age. The flakes of chimooite are 0.2 mm for the largest one, but usually less than 0.05 mm. The acicular crystals are elongated parallel to and flattened on (001). This mineral shows gradation to rancieite constituting its marginal part, thus both minerals are found in one and the same flake. Color is bluish black, with dull luster and brown streak in globular or massive aggregates. Cleavage is perfect in one direction. The hardness ranges from 2.5 to 4. Under reflected light it is anisotropic and bireflectant. It shows reddish brown internal reflection. Chemical analyses of different parts of both minerals suggest that rancieite and chimooite constitute a continuous solid solution series by cationic substitution. The empirical chemical formula for chimooite has been calculated following the general formula, $R_2_{x}$ M $n^{4+}$$_{9­x}$ $O_{18}$ $.$n$H_2O$ for the 7 $\AA$ phyllomanganate minerals, where x varies from 0.81 to 1.28 in so far studied samples, thus averaging to 1.0. Therefore, the formula of Zn­rancieite is close to the well­known strochiometric formula $_Mn_4^{4+}$ $O_{9}$ $.$4$H_2O$. The mineral has the formula (Z $n_{0.78}$N $a_{0.15}$C $a_{0.08}$M $g_{0.01}$ $K_{0.01}$)(M $n^{4+}$$_{3.98}$F $e^{3+}$$_{0.02}$)$_{4.00}$ $O_{9}$ $.$3.85$H_2O$, thus the ideal formula is (Zn,Ca)M $n^{4+}$$_4$ $O_{9}$ $.$3.85$H_2O$. The mineral has a hexagonal unit ceil with a=2.840 $\AA$ c=7.486 $\AA$ and a : c = 1 : 2.636. The DTA curve shows endothermic peaks at 65, 180, 690 and 102$0^{\circ}C$. The IR absorption spectrum shows absorption bands at 445, 500, 1630 and 3400 c $m^{1}$. The mineral name Chimooite has been named in honour of late Prof, Chi Moo Son of Seoul National University.ity.versity.ity.y.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.253-260
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• 2005

Salt accumulation in the plastic film house soils under continuous cultivation condition causes problems such as salt damages to plants, nitrate accumulation in vegetables, groundwater contamination, etc. due to excess application of fertilizers. Objective of this research was to find an optimum adsorbent to reduce salt concentration in the soil solution of plastic film house soils, where crop injuries have been observed due to the salt accumulation. The soils were significantly high in available P $(1,431{\sim}6,516mg\;kg^{-1}),\;NO_3-N\;(117.60{\sim}395.73mg\;kg^{-1})$, exchangeable Ca $(4.06{\sim}11.07\;cmol_c\;kg^{-1})$ and Mg $(2.59{\sim}18.76\;cmol_c\;kg^{-1})$, as compared to those of the average upland soils in Korea. Soils were treated with each of adsorbent such as ion-exchange resin, zeolite, rice bran, etc. at 2% level and prepared into saturated-paste samples. After equilibrium, soil solution was vacuum-extracted from the soil and measured for changes of the pH, EC, and concentrations of $Ca^{2+},\;Mg^{2+},\;K^+,\;Na^+,\;{NH_4}^+,\;{PO_4}^{3-}\;and\;{NO_3}^-$. Rice bran effectively removed ${PO_4}^{3-}\;and\;{NO_3}^-$ in the soil solution up to 100%. Efficiency was decreased in the orders of rice bran > ion-exchange resin > zeolite. Removal efficiencies of zeolite and ion-exchange resin for $Ca^{2+}$ were ranged from 1 to 65% and from 7 to 61%, respectively. Ion-exchange resin was also effective for removing $Mg^{2+},\;K^+,\;Na^+,\;and\;{NH_4}^+$. Overall results demonstrated that rice bran and ion-exchange resin could be applicable for salt accumulated soil to remove the respective anion and cation.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.25-34
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• 2013

The purpose of this study is to investigate the properties of Menyanthes trifoliata habitat in coastal lagoons. To characterize plant composition in the habitats in the lagoon, the plot sampling method was applied. The depths of water and floating mat were measured. Surface water quality factors including pH, electrical conductivity (EC), dissolved oxygen (DO), and total dissolved solids (TDS) were measured in the sites. Phosphate, nitrate, ammonium, and major cations were measured in laboratory. The wetland has 78 taxa of wetland plants. The average coverage and density of M. trifoliata was 62.6% and $71.2/m^2$, respectively and Phragmites australis is important associate in Sunyoodam lagoon. The average depths of floating mats were 26.5cm in M. trifoliata and 68.9cm in the P. australis-M. trifoliata communities, and the water depth below the mat was 106.5cm and 17.7cm, respectively. The values of pH, DO, EC and TDS in the water were 5.06, 46.1%, 59.4 ${\mu}s/cm$, and 29.3 mg/L, respectively. The concentrations of phosphate, nitrate, and ammonium showed 47.2, 9321, and 15.9 ${\mu}g/L$, respectively. The concentrations of Ca, K, Na, and Mg had 11.1, 1.5, 15.1, and 11.3 mg/L, respectively. The habitats of M. trifoliata in the lagoon corresponds to a kind of lowland communities in Hewett's classification. To conserve the habitats of M. trifoliata in Sunyoodam lagoon, the supply of open water area, the construction of observation deck, and the block of inflow from the surrounding paddy fields are needed in the future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.77-77
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• 2009

$Pb(Zr,Ti_O_3$계 세라믹스는 우수한 압전 특성으로 인하여 압전변압기 및 액츄에이터, 센서 등 많은 분야에 응용이 되어져 왔다. 그러나, 최근 들어 $1000^{\circ}C$에서 급속도로 많은 휘발을 하는 PbO는 환경 및 인체에 나쁜 영향을 미칠 뿐 아니라 사용 후의 처리도 어려워 선진국에서는 사용을 제한하거나 줄이고 있는 추세에 있다. 따라서, PbO를 포함하지 않은 무연 (Lead-free)계 압전 세라믹스에 대한 연구가 많은 관심을 끌고 있으며 앞으로는E 장래성 있는 하나의 이슈 분야가 될 것이다. 이러한 Pb-based System 세라믹스를 대체 할 재료로서 $(Bi_{1/2}Na_{1/2})TiO_3$나 Tungsten-Bronze type, $(K_{1/2}Na_{1/2})NbO_3$ 등이 주로 연구가 되고 있다. 특히, alkali niobate를 기초로 한 $(K_{1/2}Na_{1/2})NbO_3(NKN)$은 무연 압전 물질로서 많은 주목을 받고 있다. 그러나, NKN의 주요 성분인 K 의 높은 조해성 때문에 일반적인 고상방법으로는 고 밀도의 세라믹을 얻기 힘들뿐더러 낮은 상전이 온도 때문에 많은 응용에는 제약이 되고 있다. 이러한 세라믹의 단점을 보완하고자 Hot forging, RTGG, SPS 등 과 같이 특수한 소결방법을 사용하여 고밀도의 세라믹을 제작하지만 이 방법들은 제품 대량 생산에 있어 경제적으로나 복잡한 제조과정을 고려할 때 매우 비효율적이라고 판단된다. 그러므로 $BaTiO_3$, $LiTaO_3$, Mg, Ca등을 첨가 시켜 소결을 향상시키고 고밀도를 얻기 위해 많은 연구가 진행 중이다. 따라서 본 연구에서는 Pb-based계의 세라믹스를 대체할 우수한 특성의 세라믹스를 제작하고자 기존의 $(K_{1/2}Na_{1/2})NbO_3(NKN)$세라믹스에서 낮은 용융온도 때문에 소결하기 어려운 $KNbO_3$를 제거한 $NaNbO_3$에 $LiNbO_3$와 $BaTiO_3$를 추가한 $NaLiNbO_3-BaTiO_3$세라믹스에 $K_4CuNb_8O_{23}$(KCN)을 첨가함으로서 이에 따른 압전 및 유전 특성을 조사하였다.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.90-98
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• 1999

This study was conducted to select proper substrate and nutrient solution concentration for favorable growth and quality in common thyme (Thymus vulgaris L.). The growth of common thyme was better in deep flow culture (DFT) than in other substrate cultures. As the nutrient solution concentration rose, the ratio of dry matter increased, while the fresh weight and the number of lateral shoots decreased. The contents of total chlorophyll and vitamin C were higher in DFT than others. Ca, K, P were showed high contents in cocopeat, but Mg content was the highest at half-fold concentration in DFT. Common thyme showed low content of nitrate in DFT compared with that in other substrate culture. DFT was the most effective system for pronoting growth and quality of common thyme. The optimal concentration of nutrient solution in common thyme was half-fold(EC=1.2mS/cm) of herbs nutrient solution by European Vegetable R&D Center.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.195-201
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• 2011

This paper estimates the structural performance of spirally confined concrete having electric arc furnace (EAF) oxidizing slag aggregates. The EAF oxidizing slag is a by-product generated from iron and steel industry. The EAF oxidizing slag have been largely put to low-value-added uses due to its expansive properties of the free-CaO and free-MgO. Recently, this problem has been solved by the advances in steelmaking technology and thereby stabilizing EAF oxidizing slag aggregate. To verify the application of the EAF oxidizing slag aggregate to the structural concrete usage, a total of 27 cylindrical specimens with a diameter of 150 mm and a height of 300 mm were cast and tested. The test parameters were aggregate type and spiral reinforcement yield strength. Experimental results showed that the structural performance of specimens with EAF oxidizing slag aggregates was equivalent to that of confined concrete with natural aggregates.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.55-63
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• 2000

Bentonite has low hydraulic conductivity and high sorption capacity to limit hazardous heavy metals migration, and thus it has been considered as a liner material for the landfill of hazardous wastes. With a domestic bentonite sorption tests were carried out to investigate the adsorption isotherm and the effect of solution chemistry and temperature on adsorption. Freundlich isotherm was applied to fit the experimental data of lead adsorption, which fitted them well. Freundlich constants and correlation coefficient were calculated to be $K_{F}$\;=\;1.14$, n = 1.70, and $r^{2}\;=\;0.99$, respectively. The distribution coefficients($K_{d}$) for the adsorption of lead decreased with increasing initial lead concentration. The IL increased with increasing the pH of solution and sharply increased at pH > 7, which was attributed to the precipitation of lead species. The IL decreased with increasing the ion strength of solution. The $K_{d}$ gave a small increase with the concentration of ${SO_4}^{-2}$, whereas it had a nearly constant level with the concentration of ${HCO_3}^{-}$ in solution. An increase in the temperature of experimental solution increased the $K_{d}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.637-644
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• 2014

Two Chionoecetes crabs, C. opilio and C. japonicus are primary targets of trap fisheries in the East Sea. To promote the sustainable management of these species, we investigated their reproductive biology and spatial distribution based on samples collected in standardized traps in the coastal waters of eastern Korea from September 2007 to August 2008. The estimated spawning season of C. opilio was March-April, whereas that of C. japonicus continued year-round. The estimated molting period of both species was September-October. Fecundity of C. opilio was proportional to female, size, ranging from 44,791 to 151,538 eggs, and the estimated body size at 50% sexual maturity was 63.9 mm carapace width. Egg bearing female C. opilio were mostly collected depths of 200-300 m, particularly off Hupo and Chuksan, suggesting that these areas are their major spawning grounds. In contrast, female C. japonicus were mostly collected at depths of 400-600 m, peaking at 600 m. The species-specific catch rate was higher for C. opilio above 400 m, similar at ca. 450 m, and higher for C. japonicus below 500 m. These vertical differences indicate apparent spatial segregation of the species, suggesting that spatially-explicit fisheries management plans may be necessary for mitigating conflicts between the respective crab fisheries and maintaining these crabs.