• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1669-1670
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• 2006

LED have many problem as narrow light view angle, high price, drift phenomenon of color coordinate, high heating problem for lower power, lower weight and small size. But, with the development of blue LEDs and the improvement of LED brightness, color variation are becoming more and more popular as lighting and application devices in this page, 1 used the Light Tools which was a simulation program in order to recognize optical a few characteristic of LEDs arrangement along reflector matrial and designed LED Arranged 5 phi LED in 5mm interval In the square that was $10{\times}10$ And designs a reflection board on pcb, structural design of PCB changed as five type. - Aluminum, Gold. Chromium, Nickel, Copper.

• 한국표면공학회지
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• 제54권2호
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• pp.71-76
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• 2021

Ag925, silver with added copper, is popular alloy due to its low price. However, it has a difficult to use because of the low corrosion resistance. In various alloys, neodymium (Nd) works as an element to improve corrosion resistance by reacting with interstitial elements in the alloy. When 1.5 wt. % Neodymium was added to Ag925, the potential on the activated polarization in a potentiodynamic polarization test was increased from -0.15 V to -0.05 V. Ag925 with added neodymium showed the passivation after activation polarization. But When the potential increased around 50 mV, the current density is increased to 3 × 10-3. Ag925 with the 1.5 wt. % Nd had the low corrosion rate.

• 전력전자학회논문지
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• 제21권4호
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• pp.296-301
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• 2016

Using high magnetic flux from a 60 Hz high-current cable, a 2 W wireless-powered energy harvesting receiver for sensor operation, internet of things (IoT) devices, and LED lights inside electrical cable tunnels is proposed. The proposed receiver comprises a copper coil with a high number of turns, a ring-shaped ferromagnetic core, a capacitor for compensating for the impedance of the coil in series, and a rectifier with various types of loads, such as sensors, IoT devices, and LEDs. To achieve safe and easy installation around the power cable, the proposed ring-shaped receiver is designed to easily open or close using a clothespin-shaped handle, which is made of highly-insulated plastic. Laminated silicon steel plates are assembled and used as the core because of their mechanical robustness and high saturation flux density characteristic, in which the thickness of each isolated plate is 0.3 mm. The series-connected resonant capacitor, which is appropriate for low-voltage applications, is used together with the proposed receiver coil. The concept of the figure of merit, which is the product weight and cost of both the silicon steel plate and the copper wire, is used for an optimized design; therefore, the weight of the fabricated receiver and the price of raw material is 750 gf and USD $2 each, respectively. The 2.2 W powering capability of the fabricated receiver was experimentally verified with a power cable current of $100A_{rms}$ at 60Hz.

• Journal of the Korean Wood Science and Technology
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• 제36권1호
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• pp.110-123
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• 2008

환경 오염 및 인체 유해성으로 사용이 금지된 목재 방부제인 CCA를 대체하고 최근 CCA 대체방부제로 주로 사용되고 있는 고가의 구리 아졸화합물계(CUAZ)과 구리 알킬암모늄계(ACQ) 방부제를 대체하기 위하여 유기 폐기물인 두부비지를 이용하여 환경친화적인 목재방부제를 제조하였다. 목재 내로 유효성분의 용이한 주입을 위하여 다양한 농도의 황산으로 두부비지를 가수분해하였으며, 가수분해된 비지를 $CuSO_4$, $CuCl_2$, Borax 등의 금속염과 반응시켜 최종적으로 목재 방부제를 조제하였다. 이렇게 조제된 방부액은 감가압방법을 통해 목재내로 주입하였고 주입된 시편에 대한 용탈 실험을 실시하여 각 방부제의 주입능과 용탈성을 비교하였다. 비지의 산가수분해물의 이용과 암모니아수를 이용한 일시적인 해리를 통해 방부제의 유효성분이 효과적으로 주입되었으나 비지를 가수분해하기 위해 사용된 산의 농도가 높을수록 용탈량이 증가되었다. Borax의 첨가는 주입능과 용탈성에 부정적인 영향을 미쳤으나 가수분해 온도에 따른 주입능과 용탈성에는 차이가 없었다. 결과를 종합하면 비지의 1% 산가수분해물에 금속염으로 $CuCl_2$를 사용하였을 경우 생산 비용 및 환경적인 측면에서 목재방부제로 사용하기에 최적의 제조조건으로 생각되며 두부비지로 조제된 방부제의 주입능과 용탈성을 CuAz에 비교한 결과 차이가 없거나 우수한 것으로 나타나 환경친화적인 목재 방부제로서 사용가능성을 충분히 보여주었다.

• Ocean and Polar Research
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• 제31권2호
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• pp.167-176
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• 2009

Cobalt-rich manganese crusts on seamounts have received an increasing amount of attention as future resources for Co, Ni, Cu, and Mn. A dearth of detailed information regarding the relevant distribution characteristics, mining technologies, and ore processing technologies, however, has precluded potential evaluations of the technical and economic advantages of these crusts. In the past 4 years, Korea has undertaken a survey of the cobalt-rich manganese crusts in and around the Magellan Seamount and Mid-Pacific Mountains. This paper introduces the preliminary feasibility study of the distribution features and R&D results centered around the development of the cobalt-rich manganese crusts. The evaluation model was developed by modifying the model for the manganese nodules. In addition to considering the geological and geophysical differences between the manganese nodules and the cobalt-rich manganese crusts, an ore dressing subsystem was installed in the model. The mining subsystem is composed of a self-propelled collector--a pipeline with submersible hydraulic pumps for crust lifting. The smelting and chlorine leach method was selected for metallurgical processing. The production scales were established at 2,500t/y of cobalt metal. The production of three metals--cobalt, nickel, and copper--was considered in terms of metallurgical processing. The economic feasibility analyses demonstrated that the payback period was 11.4 years, the NPV was 36M$, and the IRR was 9.6% with the economic factors in the case of a cobalt price of US$ 25/lb. It was also demonstrated in this study that the payback period was 8.6 years, the NPV was 154M$, and the IRR was 14.0% in the case of a cobalt price of US$ 30/lb. This indicates that the approach under consideration appears to offer greater potential given the predicted metal prices.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.549-555
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• 2019

Electrocatalysis of oxygen reduction reaction (ORR) using Pt nanoparticles or bimetal on carabon was studied. Currently, the best catalyst is platinum, which is a limited resource and expensive to commercialize. In this paper, we investigated the cheaper and more active electrocatalysts by making Pt nanoparticles and adding 3D transition metal such as copper. Electrocatalysts were obtained by chemical reduction based on ethylene glycol solutions. Elemental analysis and particle size were confirmed by XRD and TEM. The electrochemical surface area (ECSA) and activity of the catalyst were determined by electrochemical techniques such as cyclic voltammetry and linear sweep voltammetry method. The commercialized Pt support on carbon (Pt/C, JM), synthesis Pt/C and synthesis Pt3Cu1 alloy nanoparticles supported on carbon were compared. We confirmed that the synthesized Pt3-Cu1/C has high electrochemical performance than commercial Pt/C. It is expected to develop an electrocatalyst with high activity at low price by increasing the oxygen reduction reaction rate of the fuel cell.

• 한국환경농학회지
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• 제19권5호
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• pp.401-418
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• 2000

1. Production of the artificial zeolite from coal ash Coal fly ash is mainly composed of several oxides including $SiO_2$ and $Al_2O_3$ derived from inorganic compounds remained after burning. As minor components, $Fe_2O_3$ and oxides of Mg, Ca, P, Ti (trace) are also contained in the ash. These components are presented as glass form resulting from fusion in the process of the combustion of coal. In other word, coal ash may refer to a kind of aluminosilicate glass that is known to easily change to zeolite-like materials by hydrothermal reaction. Lots of hot seawater is disposing near thermal power plants after cooling turbine generator periodically. Using seawater in the hydrothermal reaction caused to produce low price artificial zeolite by reduction of sodium hydroxide consumption, heating energy and water cost. As coal ash were reacted hydrothermally, peaks of quartz and mullite in the ash were weakened and disappeared, and new Na-Pl peaks were appeared strengthily. Si-O-Si bonding of the bituminous coal ash was changed to Si-O-Al (and $Fe^{3+}$) bonding by the reaction. Therefore the produced Na-Pl type zeolite had high CEC of 276.7 $cmol^+{\cdot}kg^{-1}$ and well developed molecular sieve structure with low concentration of heavy metals. 2. Utilization of the artificial zeolite in agro-environment The artificial zeolite(1g) could remove 123.5 mg of zinc, 164.7 mg copper, 184.4 mg cadmium and 350.6 mg lead in the synthetic wastewater. The removability is higher 2.8 times in zinc, 3.3 times in copper, 4.7 times in cadmium and 4.8 times in lead than natural zeolite and charcoal powder. When the heavy metals were treated at the ratio of 150 $kg{\cdot}ha^{-1}$ to the rice plant, various growth inhibition were observed; brownish discoloration and death of leaf sheath, growth inhibition in culm length, number of panicles and grains, grain ripening and rice yield. But these growth inhibition was greatly alleviated by the application of artificial zeolite, therefore, rice yield increased $1.1{\sim}3.2$ times according to the metal kind. In addition, the concentration of heavy metals in the brown rice also lowered by $27{\sim}75%$. Artificial Granular Zeolites (AGZ) was developed for the purification of wastewater. Canon exchange capacity was 126.8 $cmol^+{\cdot}kg^{-1}$. AGZ had Na-Pl peaks mainly with some minor $C_3S$ peaks in X-ray diffractogram. In addition, AGZs had various pore structure that may be adhere the suspended solid and offer microbiological niche to decompose organic pollutants. AGZ could remove ammonium, orthophosphate and heavy metals simultaneously. Mixing ratio of artificial zeolite in AGZs was related positively with removal efficiency of $NH_4\;^+$ and negatively with that of $PO_4\;^{3-}$. Root growth of rice seedling was inhibited severely in the mine wastewater because of strong acidity and high concentration of heavy metals. As AGZ(1 kg) stayed in the wastewater(100L) for 4days, water quality turned into safely for agricultural usage and rice seedlings grew normally.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.264-269
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• 2001

Large amounts of orange juice are produced in Japan every yea.. Accompanied by the production of orange juice, large amount of juice residues are also generated in nearly the same amounts with juice. Although, at present, some of these residues are marketed as a feed for cattle after drying and mixing with lime, the marketing price is lower than its production cost and the difference is paid by the consumers as a part of the price of orange juice. In the present work, we developed new innovative use of orange juice residue, a biomass waste, as adsorption gel for removing toxic heavy metals such as lead. arsenic, selenium and so on as well as radioactive elements such as uranium and thorium from environments. The major components of orange juice residue are cellulose. hemicellulose and pectin, which are converted into pectic. acid, an acidic polysaccharide, by means of saponification with concentrated sodium hydroxide solution. In the previous work, we found that crosslinked pectic acid gel strongly an selectively adsorbs lead over other metals such as zinc an copper. On the other hand. it is well known that polysaccharides such as cellulose can be easily phosphorylated and that phosphorylated polysaccharides have high affinity to uranium and thorium as well as some trivalent metals such as ferric iron and aluminum. Taking account of the noticeable characteristics of these polysaccharides, 2 types of adsorption gels were prepared from orange juice residue: one is the gel which was prepared by saponificating the residue followed by crosslinking with epichlorohydrin and another is that prepared by crosslinking the residue followed by phosphorylation. The former gel exhibited excellent adsorptive separation behavior for lead away from zinc owing to high content of pectic acid while the latter gel exhibited that for uranium and thorium. Both types of adsorption gels exhibited high affinity to ferric iron, which enables selective and strong adsorption for some toxic oxo-anions of arsenic (V and III), . selenium and so on via iron loaded on these gels. These results demonstrate that biomass wastes such as orange juice residue can be effectively utilized fer the purpose of removing toxic heavy or radioactive metals existing in trace or small amounts in environments.

• 전기화학회지
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• 제14권4호
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• pp.225-230
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• 2011

Copper indium gallium selenide (CIGS) 기반 박막 태양전지는 저렴한 제작 단가 및 다른 박막 태양전지에 비해 높은 효율을 보여 실리콘 기반 태양전지의 차세대 태양전지로 각광을 받고 있다. 구성 요소 중 buffer 층은 window 층과 absorber 층 사이의 높은 밴드 갭(band gap)을 해소 해주는 역할을 한다. 기존의 cadmium sulfide(CdS)의 인체 유해성 때문에 이를 대신할 indium sulfide(In2S3)를 이용한 buffer 층의 연구가 활발히 진행되고 있다. 본 연구에서는 전기화학적인 방법을 통해 값싸고 간편하게 indium sulfide buffer 층을 전극 표면에 합성하는 연구를 진행하였다. Indium-Tin-Oxide(ITO) 전극표면을 sodium thiosulfate 및 indium sulfate의 혼합물 용액에 담그고 환원 전위를 인가하여 indium sulfide를 합성하였다. 크기가 다른 두 전압을 교대로 인가하여 확산 한계(diffusion limit)를 최소화 함으로써 표면에 균일한 조성을 가지는 buffer 층을 합성해 낼 수 있었다. 또한 합성 중 온도의 조절을 통해 buffer 층의 밴드 갭을 최적화 할 수 있었다. 이렇게 전기화학적으로 합성된 buffer 층은 X-선 광전자 분광법과 회절법의 분석을 통해 ${\beta}$-indium sulfide 결정구조를 가짐을 확인 하였다.

• 설비공학논문집
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• 제25권11호
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• pp.595-599
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• 2013

The pipes used in buildings are generally categorized into metallic or plastic materials. Metal pipes, such as copper and stainless steel pipes, are mainly used for water and hot water supply, and for the heating system. However, plastic pipes made of polyethylene and cross-linked polyethylene are used for floor heating, water drainage, and air vent systems. Usually, plastic pipes have thermal demerits, such as high linear expansion coefficients and bending phenomenon by hot water, although the pipes have several merits of light weight, low price, low thermal conductivity, and the comparatively high workability of metal pipes. Therefore, if those kind of demerits are overcome, plastic pipes can be easily accepted for hot water systems. This research is aimed to evaluate the applicability for vertical heating pipes of a plastic pipe system consisting of electric fusion fitting of a conductive carbon compound and propylene random glass fiber pipe, through measurement of the expansion rate and leakage in summer and winter seasons, in the apartment construction field.