• Resources Recycling
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• v.3 no.2
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• pp.28-34
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• 1994

A part of used cables, such as electric and communication cables has already been recycled by using simple processing methods. However, it has been found that the main problems in recycling of the used cables are insufficient treatment of fine stranded wires and low recovery of copper by air separation process. It has been shown that copper can be effectively separated from the PE using a solvent treatment method. In the present study, the used communication wires having diameter of 0.4 mm are treated in the mixing solution of toluene and water at $86^{\circ}C$ for about 10 minutes. In the solvent treatment, the copper wires recovered have 10~15mm length, which are much longer than that of 1~2mm length copper wires recovered by air table concentration method used in current recycling plants. The process consisting of cutting, air separation and electrostatic separation would be recommendable for the treatment of mixed cables. In this investigation, fine copper powders can also efficiently be recovered from insulation materials using electrostatic separator at the conditions of 20~50RPM roller speed and 15~30KV high DC power.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.63-74
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• 1994

The ultrathin oxide films less than 100$\AA$ were grown by thermal oxidation in $N_2O$ ambient to improve the controllability of thickness, thickness uniformity, process reproducibility and their electrical properties. Oxidation rate was reduced significantly at very thin region due to the formation of oxynitride layer in $N_2O$ ambient and moreover nitridation of the oxide layer was simultaneously accompanied during growth. The nitrogen incorporation in the grown oxide layer was characterized with the wet chemical etch-rate and ESCA analysis of the grown oxide layer. All the oxides thin films grown in $N_2O$, pure and dilute $O_2$ ambients show Fowler-Nordheim electrical conduction. The electrical characteristics of thin oxide films grown in $N_2O$ such as leakage current, electrical breakdown, interface trap density generation due to the injected electron and reliability were better than those in pure or dilute ambient. These improved properties can be explained by the fact that the weak Si-0 bond is reduced by stress relaxation during oxidation and replacement by strong Si-N bond, and thus the trap sites are reduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.95-101
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• 2017

In this paper, the sizing removal condition for the pretreatment of composite materials is obtained numerically by applying an image processing algorithm and nickel-plated carbon fiber is fabricated by a dry process method to enhance its electromagnetic shielding performance. Sizings that are wrapped in a polymer type material during the manufacturing of carbon fiber should be removed for dry coating. A numerical value, that is the correlation, can be obtained by determining the regular pattern of the carbon fiber in the image taken by a scanning electron microscope (SEM) after the sizing is removed. The application of the proposed numerical method to the SEM image of the fiber after the sizing is removed with solution, compressed air, solution and compressed air (hybrid), showed that this method of eliminating the sizing is superior to the hybrid method. Then, by spreading the carbon fiber roll with the sizing removed, we were able to produce nickel plated carbon fiber by the roll-to-roll sputtering method. The electromagnetic shielding performance of the fabricated 30, 40 and 100 nickel coated carbon fibers was measured. The Korea Advanced Institute of Science and Technology evaluated the electromagnetic shielding performance of the 100 nickel-coated carbon fiber to have a maximum value of 73.2 (dB) and a minimum value of 66.7 (dB). This is similar to the electromagnetic shielding rate of copper and shows that this material can be used as a cable for EV / HEV automobiles.

• Journal of the Korean Wood Science and Technology
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• v.28 no.3
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• pp.34-41
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• 2000

Recently many scientists have tried to synthesize biodegradable polymers due to durable and non-biodegradable products of conventional synthetic plastics when these were wasted in nature. So to reuse the wastepapers for biodegradable polymer resources, ONP (old newsprint), OCC (old corrugated containerbpard) were carried out by the pretreatment of chlorinite, hypochlorite and oxygen-alkali treatment conditions. For manufacturing of biodegradable polymer with wastepaper, this study performed to investigate change of chemical components and optimal pretreatment condition. The summarized results in this study were as follows: Lignin content in ONP and OCC was was higher than in MOW and ash content was the highest in MOW. More amount of ash components were reduced by wet defiberation than by dry defiberation. Wet defiberation fiber are better than dry defiberated fiber in chemical pretreatment condition for wastepapers, and the best result was obtained in the condition of sodium chlorite at $70^{\circ}C$, because it has high delignification ratio, ${\alpha}$-cellulose contents and degree of polymerization in this treatment condition. Oxygen-alkali treatment condition is the worst method because of low yield, low degree of polymerization in this pretreatments.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.6
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• pp.617-624
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• 1990

Proper processing condition of Yukwa(oil popped rice snack) for mass production and pop-ping mechanism of it were tested with Shinsun (waxy, Japonica type rice) which was excellent for Yukwa making. Optimum steaming time of dough was 15 min among 4 to 60 min and reasonable moisture content of the dough before steaming was 4895 among 48 to 53% which had good and fine texture. Acceptable stirring time of steamed dough was not significantly different among 1 to 4 min, but no stirring with much larger volume was shown very poor and too soft in texture. At the simplification test of milling method, wet milling was better then dry milling in expansion rate and high temperature treatment of dough at 6$0^{\circ}C$ gave negative effect on their quality. Extending high temperature treatment of dough, reducing sugars in the dough increased and it might be caused of starch degradation. In addition of some other protein sources to dough, Yukwa quality were in proportion to the protein content of the beans. At the long term storage of the Yukwa base, moisture absorption was different depending upon RH of atmosphere and the quality of Yukwa was inferior by storage time. By addition of some alcoholic beverage, such as Makkoli, Soju and Chungju, expansion rate and their texture were somewhat improved by increasing addition amount of them from 15% to. 30％ on dough (w/w).

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.333-338
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• 2015

In this study, we investigated carbonation-regeneration and agglomeration characteristics of dry sorbents. Experiment has been proceeded in the batch-type reactor, which is made of quartz: 0.05 m of I.D and 0.8 m in height. The sorbents that is collected at the cyclone of the carbonation reactor of continuous process were used in this study. The reactivity was studied at the various concentrations of water vapor, $N_2$ and $CO_2$ in the fluidizing gas at regeneration reaction. As a result, the reactivity increased as the regeneration temperature increased, the reactivity decreased as the concentration of water vapor increased. The absorption capacity showed the highest value in case of using $N_2$ 100% as regeneration gas. And decreased in order of $H_2O+N_2$, $CO_2$ 100% and $H_2O+CO_2$. The agglomeration characteristics were investigated according to the particle sizes and concentrations of water vapor at carbonation reaction. As a result, the particle with smaller size and higher concentration of water vapor showed the higher agglomeration characteristic.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.05a
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• pp.14-14
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• 2003

Silicon carbide (SiC)는 높은 power 영역과 높은 온도영역에서도 작동 가능한 우수한 반도체 물질이다. 또한 우수한 열적 화학적, 안정성을 가지고 있어 가흑한 조건에서의 소자로써도 사용 가능하다. 현재 SiC 적용분야로는 우수한 전기적, 기계적 성질을 이용한 미세소자(MEMS)와 GaN 와 거의 유사한 격자상수를 가지는 것을 이용한 GaN epitaxial 성장의 기판으로도 사용되어진다. 그러나 SiC 는 기존의 습식식각 용매에 대해 화학적 안정성을 가지고 있기 때문에 전자소자의 제작에 있어서 플라즈마를 이용한 건식식각의 중요성이 대두되어지고 있다. 소자제작에 있어 이러한 건식식각시 식각 단면의 제어, 이온에 의한 낮은 손상 정도, 매끄러운 식각 표면, 그리고 고속의 식각 속도둥이 요구되어진다. 본 실험에서는 식각 속도의 증가와 수직한 식각 단면둥을 획득하기 위하여 SF6 플라즈마에서 Source power, dc bias voltage, 그리고 외부에서 인가되는 자속의 세기를 변화시쳐가며 식각 속도, 식각 마스크와의 식각 션택비, 식각 단면둥과 같은 SiC 의 식각 특성을 관찰하였다. 식각 후 식각 단면은 주사전자 현미경(SEM)을 통해 관찰하였다. 본 실험에서의 가장 높은 식각 속도는 분당 1850n 로써 이때의 공정조건은 1400W 의 inductive power, -600V 의 dc bias voltage, 20G 의 외부자속 세기이었다. 또한, 높은 inductive power 조건과 낮은 dc bias voltage 조건에서 Cu는 $SF_6$ 플라즈마 내에서 식각부산물의 증착으로 인해 SiC 와 무한대의 식각선택비를 보였다. 이러한 Cu 마스크를 사용한 SiC 의 식각에서는 식각 후 수직한 식각 단변을 관찰할 수 있었다. 것올 알 수 있다. 따라서, 기존의 pve 보다 세라믹 기판의 경우가 수분 흡수율이 높아 더 오랫동안 전류를 흐르게 하여 방식성이 개선된 것으로 판단된다.을 통해 경도가 증가한 시편의 경우 석출상의 크기가 5nm 이하로 매우 작고 대체로 기지와 연속적인 계면을 형성하나, 열처리가 진행될수록 석 출상의 크기가 커지고 임계크기 이상에 이르면 연속적인 계면은 거의 발견되지 않고, 대부 분 불연속적이고 확연한 계면을 형성함을 관찰 할 수 있었다. 알루미나(${\alpha}-Al_2O_3$) 기판 위에 증착한 $(Ti_{1-x}AI_{x})N$ 피막은 마찬가지로 (200) 우선 방위를 나타내었으나, 그 입자의 크기가 수십 nm로 고속도강위에 증착한 피막에 비해 상당히 크게 형성되었다. 또한 열처리 후에 AIN의 석출이 진행됨에도 불구하고 경도 증가는 나타나지 않고, 열처리가 진행됨에 따라 경도가 감소하는 양상만을 나타내었다. 결국 $(Ti_{1-x}AI_{x})N$ 피막이 열처리 전후에 보아는 기계적 특성의 변화 양상은 열역학적으로 안정한 Wurzite-AlN의 석출에 따른 것으로 AlN 석출상의 크기에 의존하며, 또한 이러한 영향은 $(Ti_{1-x}AI_{x})N$ 피막에 존재하는 AI의 함량이 높고, 초기에 증착된 막의 업자 크기가 작을 수록 클 것으로 여겨진다. 그리고 환경의 의미의 차이에 따라 경관의 미학적 평가가 달라진 것으로 나타났다.corner$적 의도에 의한 경관구성의 일면을 확인할수 있지만 엄밀히 생각하여 보면 이러한 예의 경우도 최락의 총체적인 외형은 마찬가지로 $\ulcorner$순응$\lrcorner$의 범위를 벗어나지 않는다. 그렇기 때문에

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.224-230
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• 2001

The characteristics of $NO/N_2O$ annealed reoxidized nitrided oxide being studied as super thin gate oxide and gate dielectric layers of Non-Volatile Semiconductor Memory (NVSM) were investigated by Dynamic Secondary Ion Mass Spectrometry (D-SIMS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), and Auger Electron Spectroscopy (AES). The specimen was annealed by $NO/N_2O$ after initial oxide process and then rcoxidized for nitrogen redistribution in nitrided oxide. Out-diffusion of incorporated nitrogen during the wet oxidation in reoxidation process took place more strongly than that of the dry oxidation. It seems to indicate that hydrogen plays a role in breaking the Si N bonds. As reoxidation proceeds, incorporated nitrogen of $NO/N_2O$ annealed nitrided oxide is obsen-ed to diffuse toward the surface and substrate at the same time. ToF-SIMS results show that SiON species are detected at the initialoxide interface, and Si,NO species near the new $Si_2NO$ interface that formed after reoxidation. These SiON and $Si_2NO$ species most likely to relate to the origin of the state of memory charge traps in reoxidized nitrided oxide, because nitrogen dangling bonds of SiON and silicon dangling bonds of $Si_2NO$ are contained defects associated with memory effect.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.2
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• pp.41-48
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• 2020

In this study, organic carbon was extracted from the condensed water of food waste drying process to estimate the applicability as external organic carbon sources. The COD, TN, TP and TS of condensed water were 21,374 mg/L, 148 mg/L, 4.19 mg/L, and 455.7 mg/L, respectively. In addition, the content of biodegradable organics in condensed water was 47%. The fractional distillation and the vacuum evaporation were employed for extracting organic carbon. There were 8 extraction conditions, but 4 conditions were available for extraction. They were 1) 0mmHg, 110℃ 2) -600mmHg, 70℃ 3) -500mmHg, 80℃ 4) -600mmHg, 80℃. All 4 conditions showed the highest organic concentration and the highest quantity of organics when extracted 10% of initial volume. It was estimated that optimum conditions were 80℃, -600mmHg and 10% extraction. Then, extraction concentration, extraction quantity, extraction efficiency, extraction time, BOD/TCOD ratio, TVFAs/TCOD ratio and NH₃-N were 174,200 mg/L, 8,710 mg, 46%, 10 min, 0.97, 0.74 and 75.5 mg/L respectively. Therefore, the extracted organic carbon can be utilized as external organic carbon sources.

• Clean Technology
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• v.18 no.3
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• pp.287-294
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• 2012

In this study, performances of two cleaning methods were analyzed and a cleaning system was designed to develop a cleaning process of electronic components to remanufacture old laser copy machine. First, plasma cleaning as a dry cleaning method was executed to test cleaning ability. In cleaning of printed circuit board (PCB) by plasma, some damages were found near the metal parts, and considering the productivity, this method was not adequate for the cleaning of electronic components. With 4 different cleaning agents, ultrasonic cleaning tests were executed to select an optimal cleaning agent, aqueous agents showed superior cleaning performance compared to semi-aqueous and non-aqueous agents. Cleaning with aqueous cleaning agent A and 28 kHz ultrasonic frequency can be completed in 30 sec to 1 min. Finally, an ultrasonic cleaning system was constructed based on the pre-test results. Optimal cleaning conditions of 40 kHz and $50^{\circ}C$ were found in the field test. The productivity and economic efficiency in remanufacturing of laser copy machine are expected to increase by adapting developed ultrasonic cleaning system.