• Natural Product Sciences
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• v.8 no.3
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• pp.83-89
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• 2002

Butea monosperma Kuntze, commonly known as 'Palash', is employed in various indigenous systems of medicine against several diseases and almost every part of the plant has diversified medicinal properties. The seeds are used as anthelmintic, aperient, digesti and to treat piles, skin diseases and abdominal troubles. They also have the property of reducing 'Kapha' and 'Vata' (in Ayurveda). In the present paper a detailed pharmacognostical evaluation of seeds has been undertaken. The study includes macro- and micro-scopical details, fluorescence powder study and HPTLC fingerprinting. The seed is characterized by finely ridged seed coat and palisade-like malpighian cells, discontinuous transparent linea lucida in upper half of malpighian layer and simple & oblong hilum. The study also concludes that the seed samples procured from different places have similar morphological and physico-chemical characteristics. These observations are also supported by similar TLC profiles. The estimation of heavy metals (to detect permissible toxic limits), and fatty acid composition have been carried out. An attempt has also been made to see the ecological and edaphic variations, if any.

• Journal of the Korean Professional Engineers Association
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• v.19 no.1
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• pp.25-32
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• 1986

The number of visiters to Bukhan Mt. national park, generation quantity of solid waste and collection system were researched to consider a counterplan for the pollution control of the national park and study for developing the effective treatment of solid waste was tried through the proximate analysis of each component containing. Results obtained in this study were summerized as follows; The great part of visitors go on an excursion to the Bukhan Mt. national park during July and August and also, the solid waste was generated nearly a half of the total amount at the same period. The major collection facilities in the national park were waste basket and incineration box. But the incineration box was too large in volume and very far in distance, and its collection period was irregular, so it was cause to the congestion of solid waste and bad smell and dirty. Therefore, to complete collection of solid waste, we must set up the waste basket which able to find within 40～50m from the origination place of solid waste and induce the visitors to throw the solid waste. It was obtained as moisture content: 48.5 wt%, volatile solid: 28.4wt％, fixed solid: 23.1 wt％, lower heating value: 1,320kca1/kg from experimental analysis of solid waste. According to this analysis, the incineration operation is possible, but the generation quantity of solid waste was too small to construct incineration plant for heat recovery. It was found that it is suitable for the aerobic composting by mixing with the night soil which generate in the national park after the recovery of resources such as metals, glasses and plastics.

• The Korean Journal of Ecology
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• v.18 no.3
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• pp.341-351
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• 1995

The relationship between land uses and water quality was investigated at Kyong-an Stream. Some 70% of this watershed was forested area, half of which was comprised of Pinus densilflora community. Concentrations of $NH_4^{+},\;NO_3^{-},\;NO_2^{-}, total nitrogen, $Cl^{-},\;PO_4^{3-}$, DO, and BOD increased gradually from upstream to downstream, whereas heavy metals did not have such tendancy with the exception of a few sites. Urban area was significantly correlated with hardness and chloride concentration. Relationship among phosphate concentration(P), cultivated field area(F), and stream length(S) in each basin was P = 1.7912 F/S＋0.0103. the concentration of $NH_4^{＋}$ was positively correlated with the population size and cow density within the catchment. The effect of urban area(U) and stream length of the pH(pH) was represented by pH = -4.7344 U/S＋6.52. It can be concluded that the control of nonpoint source pollution as well as point source pollution is one of the important problems of water quality management, especially geological properties must be considered for sustainable development.

• Transactions on Electrical and Electronic Materials
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• v.9 no.5
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• pp.206-208
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• 2008

Implantation of metals and ceramics with ions of nitrogen and other species has improved surface properties such as friction, wear and corrosion in numerous industrial applications. In recent years, PCB drills tend to be more minimized increasingly as the electronics components have been more highly accumulated and minimized. Therefore nitrogen ion implantation was performed onto PCB drill (0.15 & 0.3 mm in diameter), in order to investigate mechanical properties of WC-Co cermets surface through Nano-indentation tests. PCB drill was implanted at energy of 70 keV, 90 keV, 120 keV and with the dose range of $1{\times}10^{17}$ and $5{\times}10^{17}\;ions/cm^{2}$. After ion implantation, WC-Co PCB drill bits was tested in actual operating situation to apply cutting tools industry and is concluded that the life time of nitrogen ion implanted PCB drills is one and a half times longer than the unimplanted.

• Asian Journal of Turfgrass Science
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• v.11 no.4
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• pp.303-309
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• 1997

The investigation was cycle of aluminum of surface soil elements in dynamic grassland ecosystems at a steady state in a Zoysia japonica and a Miscanthus sinensis ecosystem in Mt. Kwanak, Korea. Average amounts of total storage for aluminum in Z japonica and M. sinensis grasslands were 8,426mg /$m^2$ and 7,849mg /$m^2$ respectively. Decay constants estimated on the base of experimental and mathematical model, were 0.04 in Z japonica grassland, and 0.08 in M. sinensis grassland. Half time to decay aluminum of litter soils were 17.33 years in Z japonica grass-land, and 8.66 years in Al. sinensis grassland. 95% decay times in Z japonica, and in M. sinensis grassland were 75.0 years and 35.0 years respectively. Needed times to lose almost all of elements in Z japonica and M. sinensis grassland were 125.0 years, and 62.50 years respectively. The metals were losed more rapidly in M. sinensis than in Z japonica grassland. The cycle of aluminum was investigated to be related with soil acidity. Key words: Cycle of aluminum, Zoysia japonica. Miscanthus sinensis, Mt. Kwanak, Decay constants, Soil acidity.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1225-1232
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• 2023

The ¹⁸⁰W is the lightest isotope of Tungsten with small abundance ratio. It is slightly radioactive (α decay), with an extremely long half-life. Its separation is possible by non-conventional single withdrawal cascades. The ¹⁸⁰W is used in radioisotopes production and study of metals through gamma-ray spectroscopy. In this paper, single withdrawal cascade model is developed to evaluate multicomponent separation in non-conventional transient cascades, and available experimental results are used for validation. Numerical studies for separation of ¹⁸⁰W in a transient single withdrawal cascade are performed. Parameters affecting the separation and equilibrium time of cascade such as number of stages, cascade arrangements, feed location and flow rate for a fixed number of gas centrifuges (GC) are investigated. The Salp Swarm Algorithm (SSA) as a bio-inspired optimization algorithm is applied as a novel method to minimize the feed consumption to obtain desired concentration in the collection tank. Examining different cascade arrangements, it is observed in arrangements with more stages, the separation is further efficient. Based on the obtained results, with increasing feed flow rate, for fixed product concentration, the cascade equilibrium time decreases. Also, it is shown while the feed location is the farthest stage from the collection tank, the separation and cascade equilibrium time are well-organized. Finally, using SSA optimal parameters of the cascade is calculated, and optimal arrangement to produce 5 gr of ¹⁸⁰W with 90% concentration in the tank, is proposed.

• Journal of Electrochemical Science and Technology
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• v.14 no.2
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• pp.105-119
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• 2023

The electrochemical chlorine evolution reaction (CER) is an important electrochemical reaction and has been widely used in chlor-alkali electrolysis, on-site generation of ClO^-, and Cl₂-mediated electrosynthesis. Although precious metal-based mixed metal oxides (MMOs) have been used as CER catalysts for more than half a century, they intrinsically suffer from a selectivity problem between the CER and parasitic oxygen evolution reaction (OER). Hence, the design of selective CER electrocatalysts is critically important. In this review, we provide an overview of the fundamental issues related to the electrocatalysis of the CER and design strategies for selective CER electrocatalysts. We present experimental and theoretical methods for assessing the active sites of MMO catalysts and the origin of the scaling relationship between the CER and the OER. We discuss kinetic analysis methods to understand the kinetics and mechanisms of CER. Next, we summarize the design strategies for new CER electrocatalysts that can enhance the reactivity of MMO-based catalysts and overcome their scaling relationship, which include the doping of MMO catalysts with foreign metals and the development of non-precious metal-based catalysts and atomically dispersed metal catalysts.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.238-243
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• 2001

Mass reduction and physicochemical properties of the produced compost were investigated during composting domestic food wastes without additive. A small composter used in this study had the height of 15 cm from the center of bottom half circle (diameter 24 cm) up to under the lid, the side length of 50 cm and the horizontal lid angle of $50^{\circ}$ and was operated at the heating unit temperature of $85^{\circ}$. It was mixed by the rotating arm for two minutes in every half hour while supplied with air flow at 3 L/min for 10 minutes in every half hour. This condition was found in a preliminary experiment as optimal for keeping the water content of composting material in the optimal range without adding any bulking materials. The domestic food wastes were added into the composter at the rate of 1 kg/day without additives during composting. The results were as follows; during the composting process, water content maintained in the range of $51.0{\sim}53.5%$. Hemicellulose and lignin contents did not show any tendency, but cellulose content decreased. During the composting process, $NH_3-N$ and $NO_2-N$ were not detected due to nitrification. The contents of inorganic compounds did not increase during the composting process. They were in the range of $1.32{\sim}1.71%\;P_2O_5$, $1.29{\sim}1.48%\;CaO$, $0.41{\sim}0.49%\;MgO$, and $0.38{\sim}0.74%\;K_2O$. For 20 days, weight reduction rate was 67.5% in wet basis, and decomposition rate was 48% in dry basis. Concentration of heavy metals (Cu, Cr, Cd, Pb, Zn, Hg, As) was less than the limiting value of the compost. Maturity of the produced compost was 3 grade through reaching maximum temperature of $46{\sim}48^{\circ}C$.

• Journal of the Korean Magnetics Society
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• v.18 no.5
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• pp.163-167
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• 2008

The electronic structure and magnetism of superlattice systems consisted of Heusler compound $Co_2MnSi$ (CMS) and zinc-blende MnAs (MA) are investigated by means of the all-electron full potential linearized augmented plane wave method within the generalized gradient approximation. Four superlattice systems are considered, that is CMS(m)/MA(n), where m and n, being either 2 or 4, denote the number of alternatingly arrayed layers of the compounds in a superlattice along [001] direction. From the calculated total magnetic moments as well as the total density of states, it is found that neither of the four systems is half-metallic. It is also found that the Mn atoms are antiferromagnetically coupled in the systems of CMS2/MA2 and CMS2/MA4. The total and atom-resolved density of states of the four superlattices are compared with those of the bulk $Co_2MnSi$ and MnAs, and the influences of the change in the systems symmetry on the magnetism and half-metallicity are discussed.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.1-28
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• 1990

The severe atrophic edentulism with poor neuromuscular control militates against successful conventional denture therapy. To such situation, a prescribing of dental implant treatment has been considered with some probability. Implant materials used as a trial for dental implants includes metals, plastic polymers and ceramics. The purpose of this study was to observe histologic response in osseointegration process at titanium implant-tissue interface based on biocompatibility at specific period of sequential natures which were divided into a half month, one, month, two months, three months and immediate as a base line. In this study, unilateral lower left premolar and molar teeth were extraced in three dogs. After allowing to heal for 6 months, three kinds of osseointegrated implant, $Br{\aa}nemark$, Corevent and kimplant(a prototype of SNU implant study)were inserted in each dog respectively according to the above sequence from front to back. The specimens were taken from those dogs at the same time since implant were inserted quite reverse order of the specified periods, and decalcified and processed for histologic examination for the light microscopy and the electron microscopy. The microscopic histologic findings at the interface between titanium implants and tissue were interpretated as follows : A. Light microscopic findings : a. Immediate : Implant were surrounded by compact bone and spongy bone. Microcrak was observed in the superficial bone tissue. Osteocytes were disappeared and bone lacunae were observed as a vacant space in some parts. In the contacting with the spongy bone, bone trabeculae and bone marrow were in contact with the implant. b. A half Month : Osteoblasts exist as a monolayer in th inner bone trabeculae and do bone additiocn. Osteoblasts&inflammatory cells were observed in some parts. c. One Month : The presence of osteoclasts decreased. Osteoblasts did active bone fromation, and bone marrow was in contact with the implant in the many places. d. Two Months : Bone formation was advanced in comparison with the b and c. The presence of osteoclsts was not observed. e. Three Months : The superficial bone tissue contacted with the implants was entirely composed by the compact bone. B. Electron microscopic findings : a. A half month and one month group : In the parts of the active bone formation, osteoblasts with the well developed endoplasmic reticulum and Golgi apparatus were arranged in the monolayer. In the parts of the bone resorption, ruffled border was well developed and many osteoclasts with the well-developed golgi apparatus, mitochondria, vacuole, vesicle and lysosome were existed. b. Three months group : No osteoblasts were observed in the superficial bone tissue. Bone matrix with collaen fiber was observed. c. No significant dirrerence in the histologic findings was observed in $Br{\aa}nemark$, Core-vent and kimplant.