• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.227-238
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• 2016

This review article highlights different types of nano-sized catalysts for the selective alcohol oxidation to form aldehydes (or ketones) with supported or immobilized metal nanoparticles. Metal nanoparticle catalysts are obtained through dispersing metal nanoparticles over a solid support with a large surface area. The nanocatalysts have wide technological applications to industrial and academic fields such as organic synthesis, fuel cells, biodiesel production, oil cracking, energy conversion and storage, medicine, water treatment, solid rocket propellants, chemicals and dyes. One of main reactions for the nanocatalyst is an aerobic oxidation of alcohols to produce important intermediates for various applications. The oxidation of alcohols by supported nanocatalysts including gold, palladium, ruthenium, and vanadium is very economical, green and environmentally benign reaction leading to decrease byproducts and reduce the cost of reagents as opposed to stoichiometric reactions. In addition, the room temperature alcohol oxidation using nanocatalysts is introduced.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.185-191
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• 2001

The morphological variation and density of the Euglena viridis cells and environmental factors of urban waterways of Daejoncheon , Jeonjucheon, Kwangjucheon, Kumhogang, Mihocheon,and Musimcheon, Korea were studied from 25December, 1995 to 5 January, 1997 in order toelucidate possible relationships among the bio-logical and abiological factors. All E. viridis cells were same in having single star-cluster of chlo-roplast lobes and included two morphotypes based on other detailed morphology. The morphotype I cells agreed well with the typical form off. viridrs and commonly occurred in most of waters and bloomed with $5386\;cells\;{\cdot}\;mL^{-1}$ in Kwangjucheon. The density of the morphotype Ipositively correlated with ammonium (r = 0.80)and nitrite (r = 0.68), while negatively with nit-rate concentration. The morphotype II cells were characterized by having randomly scattered cytoplasmic granules beneath pellicle and unevenmargined lobes of chloroplasts. The density of the morphotype II positively correlated with nitrate (r = 0.98), while negatively correlated with ammonium and nitrite. However, the density of each morphotype was not significantly related with inorganic phosphate, temperature and pH of surface water. These results indicate that E. viridis includes two morphotypes in urban waterways in Korea, that coexist in the same period and station as a response of allocation of nitrogenous nutrients.

• Clean Technology
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• v.10 no.4
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• pp.221-228
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• 2004

Ethoxylated Nonyl Phenol Series (NP-series), nonionic surfactants, were applied for forming microemulsions in supercritical $CO_2$. Measurement results of the solubility in supercritical $CO_2$ are in the following; NP-series were high soluble in carbon dioxide in spite of the fact that those were not $CO_2$-philic surfactants traditionally well known. Water in $CO_2$ microemulsions were also formed stably. A complexation of hydrophilic lengths for $CO_2$-philic parts of NP-Series surfactants was optimized by NP-4 surfactant(N=4) for forming the microemulsions through the experiments. Formation of microemulsions was confirmed by measuring the UV-Visible spectrum through a spectroscopic method and existence of water in the microemulsions was confirmed as well. In order to apply it for a metal surface treatment or electroplating, an experiment for forming acid(organic, inorganic) solution in $CO_2$ microemulsions was carried out. Ionic surfactant in the reaction to an acid solution became unstable to form microemulsions, however, nonionic surfactant was formed stably in the reaction. Results of the study will be utilized for expanding the application scope of supercritical $CO_2$ which is an environmental-friendly solvent.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.4
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• pp.491-498
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• 2018

The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.

• Proceedings of the Korean Magnestics Society Conference
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• 2010.06a
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• pp.79-79
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• 2010

Semimetallic bismuth (Bi) has been extensively investigated over the last decade since it exhibits very intriguing transport properties due to their highly anisotropic Fermi surface, low carrier concentration, long carrier mean free path l, and small effective carrier mass $m^*$. In particular, the great interest in Bi nanowires lies in the development of nanowire fabrication methods and the opportunity for exploring novel low-dimensional phenomena as well as practical application such as thermoelectricity[1]. In this work, we introduce a self-assembled interconnection of nanostructures produced by an on-film formation of nanowires (OFF-ON) method in order to form a highly ohmic Bi nanobridge. A Bi thin film was first deposited on a thermally oxidized Si (100) substrate at a rate of $40\;{\AA}/s$ by radio frequency (RF) sputtering at 300 K. The sputter system was kept in an ultra high vacuum (UHV) of $10^{-6}$ Torr before deposition, and sputtering was performed under an Ar gas pressure of 2m Torr for 180s. For the lateral growth of Bi nanowires, we sputtered a thin Cr (or $SiO_2$) layer on top of the Bi film. The Bi thin films were subsequently put into a custom-made vacuum furnace for thermal annealing to grow Bi nanowires by the OFF-ON method. After thermal annealing, the Bi nanowires cannot be pushed out from the topside of the Bi films due to the Cr (or $SiO_2$) layer. Instead, Bi nanowires grow laterally as a mean s of releasing the compressive stress. We fabricated a self-assembled Bi nanobridge (d=192 nm) device in-situ using OFF-ON through annealing at $250^{\circ}C$ for 10hours. From I-V measurements taken on the Bi nanobridge device, contacts to the nanobridge were found highly ohmic. The quality of the Bi nanobridge was also proved by the high MR of 123% obtained from transverse MR measurements. These results manifest the possibility of self-assembled nanowire interconnection between various nanostructures for a variety of applications and provide a simple device fabrication method to investigate transport properties on nanowires without complex patterning and etching processes.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.266-277
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• 1995

The adult brown planthopper possesses tow oval shaped compound eyes which, on their ventral borders, curve around the base of the antennae. Compound eye of the adult brown planthopper is recognised apposition eye which each ommatidium is optically isolated from it surroundings, the rhabdoms receiving light only from their own corneal lens. Each ommatidium possesses its own dioptric apparatus formed from the cuticular cornea and an underlying crystalline cone. The retinula cells lying immediately beneath the crystalline cone have their individual rhabdomeres tightly opposed to form one central, closed rhbdom. The rhabdom stretches from the spex of the crystalline cone nearly to the basement membrane and is approximately 110~120 $\mu\textrm{m}$ in length. The crystalline cone is surrounded by a pair of primary pigment cells an these in turn are surrounded by accessory pigment cells. Accessory pigment cells extend beyond the crystalline cone surrounding the retinular cells in the distal region of the eye. The crystalline cone is surrounded by the distal-most regions of the retinula cells show the presence of seven cells and sections taken proximally in the last quarter of the omatidium before the basement membrane is reached, reveal the presence of a small, eighth retinula cell which also contributes to the central rhabdom. Each ommatidium has a central rhabdom formed from the modified inner border of all of the retinula cells. Th rhabdom consists of micrvilli arising from the inner wall of each retinula cell. In cross section th microvilli exhibit a characteristic honeycomb appearance. Pigment cells comprise the primary pigment cells enveloping the crystalline cone, the accessory pigment cells extending from the inner surface of the comea to the basement membrane and the small pigment cells of the basement membrane.

• Development and Reproduction
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• v.2 no.1
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• pp.75-80
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• 1998

메기 정자는 그 길이가 약 62.5 \mu m이며 구형의 핵, 짧은 중편 및 꼬리를 ㄱ진 일반적인 메기류 정자의 미세구조적 특징을 나타내었다. 정자는 대부분의 경골어류의 정자에서와 같이 첨체를 가지고 있지 않았으며 염색질은 완전치 농축되어 있었다. 핵와(nuclear fossa)는 약 0.6 \mu m 함입되어 있었고 그 속에 기부 중심립과 말단 중심립의 일부가 포함되어 있었다. 두 중심립은 140 \circ C의 각도로 배열되어 있었으며 말단 중심립에서 9개의 부수체가 언형질막을 향하여 배열되어 있었다. 미토콘드리아는 중편 세포질에서 2층 또는 3층으로 배열되어 있었으며 핵의 후반부와 꼬리의 기부를 둘러싸고 있었다. 꼬리는 축사만으로 구성되어 있었으며 lateral fins는 관찰되지 않았다. 메기 정자의 가장 큰 구조적 특징은 중편 세포질에 구성되어 있는 관구조(tubular structure)이었다. 대부분의 경골어류의 정자는 중편 세포질에 미토콘드리아만을 포함하고 있으나, 메기 정자에서는 중편 세포질의 전반부에 미토콘드리아가 포함되어 있고, 후반부에는 소관이 모여 망상구조를 형성하는 관구조가 잘 발달되어 있었다. 이와 같은 관구조는 현재까지 Characiformes의 정자 이외의 다른 경골어류에서는 보고된 바 없으며 이러한 구조는Characiformes과 메기류의 계통학적 관계를 연구하는데 매우 중요한 형질로 여겨진다. ^u The spermatozoa of Silurus asotus are appoximately 62.5 \mu m in length and relatively simple cells composed of spherical head, a short midpiece and a tail as in most Siluriformes. The ultrastructure of the spermatozoa of S. asotus is characterized by the following features. The nucleus measuring about 1.5 \mu m in length is depressed with a deep nuclear fossa of about 0.6 \mu m in length, two fifth of the nuclear diameter. The fossa contains the proximal centriole and the half of the distal centriole. Two centrioles form an angle of approximately 140 \circ to each other. the nine satellite rays radiate from the outer surface of the distal centriole. the mitochondrea surround the basal nucleus and the axoneme, and are arranged in two or three layers in the postnuclear cytoplasm. The lateral fins are lost in the sperm tail. The most significant feature is manifested in the midpiece. The midpece comprises two parts, the mitochondria and the tubular structure unlike other teleost fishes containing only the mitochondria. The tubular structure was reported only in the spermatozoa of Citharinus belonging to the characiformes of teleost fishes. Thus it is considered to be a good characteristics for the study of phylogenetic link between Siluriformes and Characiformes.

• Economic and Environmental Geology
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• v.28 no.4
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• pp.395-404
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• 1995

The geologic structure of the Cheju volcanic island has been investigated by analyzing the gravity and magnetic data. Bouguer gravity map shows apparent circular low anomalies at the central volacanic edifice, and the maximum difference of the anomaly values on the island appears to be 30 mgal. The subsurface structure of the island is modeled by three-dimensional depth inversion of gravity data by assuming the model consists of a stacked grid of rectangular prisms of volcanic rocks bounded below by basement rocks. The gravity modeling reveals that the interface between upper volvanic rocks and underlying basement warps downward under Mt. Halla with the maximum depth of 5 km. Magnetic data involve aeromagnetic and surface magnetic survey data. Both magnetic anomaly maps show characteristic features which resemble the typical pattern of total magnetic anomalies caused by a magnetic body magnetized in the direction of the geomagnetic field in the middle latitude region, though details of two maps are somewhat different. The reduced-to-pole magnetic anomaly maps reveal that main magnetic sources in the island are rift zones and the Halla volcanic edifice. The apparent magnetic boundaries inferred by the method of Cordell and Grauch (1985) are relatively well matched with known geologic boundaries such as that of Pyosunri basalt and Sihungri basalt which form the latest erupted masses. Inversion of aeromagnetic data was conducted with two variables: depth and susceptibility. The inversion results show high susceptibility bodies in rift zones along the long axis of the island, and at the central volcano. Depths to the basement are 1.5~3 km under the major axis, 1~1.5 km under the lava plateau and culminates at about 5 km under Mt. Halla. The prominent anomalies showing N-S trending appear in the eastern part of both gravity and magnetic maps. It is speculated that this trend may be associated with an undefined fault developed across the rift zones.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.731-736
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• 2019

In this article, Pt/TiO₂ was manufactured in the form of powder and honeycomb, and the influence of SO₂, which is a poisonous substance to catalyst, and regeneration method were investigated. The catalytic activity of Pt/TiO₂ before and after the exposure to SO₂ was also compared. The initial activity of Pt/TiO₂ was proportional to the injected H₂ concentration (1~5%). And the optimum temperature of the catalyst and conversion rate of H₂ were 183 ℃ and 95%, respectively. It was confirmed that when exposing 2,800 ppm of SO₂ to the powder and honeycomb Pt/TiO₂, the performance of catalyst was not measurable and also 0.69% sulfur (S) remained on the catalyst surface. As a result of the cleaning and heat treatment for the poisoning catalyst, the activity of the powder catalyst exhibited a conversion rate of H₂ greater than 96%. Whereas, the honeycomb catalyst showed a conversion rate of H₂ greater than 95% when it was regenerated through the heat treatment of H₂ or air atmosphere.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.49-54
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• 2007

This study was conducted to determine effects of composted livestock manure application on soil nutrient change. PVC pot $(30\times100cm)$ was filled with either volcanic ash soil (Gujwa series) or non-volcanic ash soil (Aewol series) and the 20 cm surface soils were applied with composted livestock manures of cattle pig and poultry at the rates of 0, 50, 100 and 150 ton/ha, respectively. After 210 days soils samples of phosphate, potassium, calcium, and magnesium affected by application of the compost. The applied composted were equivalent to the application of organic matter of $23\sim111$ ton/ha and nitrogen of $80\sim450$ ton/ha. Availability rate of phosphate after the application of composted livestock manures ranged from 1.6 to 91.7% according to the different composted. It was much higher in the non-volcanic ash soil than in the volcanic ash soil. Availability rate of potassium fractional recovery rate change ranged from 22 to 94% according to the different manures. It was larger in the composted Availability rate of calcium 38 to 93% and $9\sim90%$ in volcanic ash soil and non-volcanic ash soil, respectively, It was higher in the composted manures followed by cattle and composted pig manures. Availability rate magnesium ranged from 12 to 41% and $1\sim9%$ in volcanic ash soil and non-volcanic ash soil, respectively. The rate was higher in the composted poultry manure followed by pig and composted cattle manures.