• 한국생산제조학회지
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• 제19권1호
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• pp.57-64
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• 2010

Metal Injection Molding (MIM) is attractive because it produces consistent, complex-geometry components for high-volume, high-strength, and high-performance applications. Also MIM using in optical communication field, display field, and semi-conductor field is a cost-effective alternative to metal machining or investment casting parts. It offers tremendous single-step parts consolidation potential and design flexibility. The objective of this paper is to study the suitability of design, flow analysis, debinding and sinterin processes, and capability analysis. The suitable injection conditions were 0.5~1.5 second filling time, 11.0~12.5 MPa injection pressure derived from flow analysis. The gravity of the product is measured after debinding an sintering. The maximum and minimum gravity levels are 7.5939 and 7.5097. the average and standard deviation are 7.5579 and 0.0122; when converted into density, the figure stands at 98.154%. According to an analysis of overall capacity, PPM total, which refers to defect per million opportunities(DPMO), stands at 166,066.3 Z.Bench-the sum of defect rates exceeding the actual lowest and highest limits-is 0.97, which translates into the good quality rate of around 88.4% and the sigma level of 2.47.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.67-67
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• 2009

Due to the scaling down of the dielectrics thickness, the leakage currents arising from electron tunneling through the dielectrics has become the major technical barrier. Thus, much works has focused on the development of high k dielectrics in both cases of memories and CMOS fields. Among the high-k materials, $Al_2O_3$ considered as good candidate has been attracting much attentions, which own some good properties as high dielectric constant k value (~9), a high bandgap (~2eV) and elevated crystallization temperature, etc. Due to the easy control of ion energy and flux, low ownership and simple structure of the inductively coupled plasma (ICP), we chose it for high-density plasma in our study. And the $BCl_3$ was included in the gas due to the effective extraction of oxygen in the form of BClxOy compound. In this study, the etch characteristic of ALD deposited $Al_2O_3$ thin film was investigated in $BCl_3/N_2$ plasma. The experiment were performed by comparing etch rates and selectivity of $Al_2O_3$ over $SiO_2$ as functions of the input plasma parameters such as gas mixing ratio, DC-bias voltage and RF power and process pressure. The maximum etch rate was obtained under 15 mTorr process perssure, 700 W RF power, $BCl_3$(6 sccm)/$N_2$(14 sccm) plasma, and the highest etch selectivity was 1.9. We used the x-ray photoelectron spectroscopy (XPS) to investigate the chemical reactions on the etched surface. The Auger electron spectroscopy (AES) was used for elemental analysis of etched surface.

• 한국가구학회지
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• 제22권3호
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• pp.174-182
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• 2011

Over the last decade, Sick Building Syndrome has become a significant social issue in Korea and many methods have been considered to maintain comfortable indoor air quality. To reduce toxic substances emitted from wood composite products, the source control is an efficient method through the reduction of formaldehyde content by using natural material-based adhesives for composite wood products production. Among alternative materials, soybean protein is considered an appropriate natural material to replace formaldehyde-based resin and many efforts have been made to produce new products, such as soap, shampoo, ink, resin, adhesive and textile through changing the chemical or physical properties of soybean. To process soybeans into these useful products, the beans are dehulled and the oil is removed by crushing at very high pressure or by solvent extraction. For use soybean as an adhesive, it is processed at temperatures below $70^{\circ}C$ to preserve the alkaline solubility of the proteins. In addition, soybean-based adhesive is undergone treatment process to improve mechanical properties using urea, urease inhibitor N-(n-butyl) thiophosphoric triamide and sodium dodecyl sulfate. The modified soybean-based adhesive exhibited sufficient mechanical properties to use as an adhesive for composite wood products. This paper is a review article to discuss the possibilities of soybean-based adhesive for environment-friendly furniture materials.

• 한국산업보건학회지
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• 제21권1호
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• pp.1-10
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• 2011

Generally, the tire curing process is the process in which the sulfur is added and subsequently the tire is heated to give the tire elasticity. In this process, all kinds of the chemicals in the tire are emitted with a lot of heat. The chemical fume and heat aggravate the work environment. To solve this problem, 92 local exhaust ventilators and 8 gravity ventilators were used, but not satisfactory yet. Preliminary survey showed that the temperatures in the process were very high: 30.3, 32.9 and $37.2^{\circ}C$ at 2, 4 and 6m above the ground level, respectively in the winter (outside temperature was $2^{\circ}C$). It can be imagined that the process is severely hot in the summer time. The higher temperature distribution in the higher space tells us that the hot plume could not be removed with the existing ventilation systems. Therefore, in this study, some alternative ventilation systems were designed. The partitions were used to contain the hot plume to increase the capture efficiency. The gravity ventilators were newly designed to improve the extraction efficiency of hot fume. To satisfy the balance of pressure in the curing process, some supply air system was introduced by renewing the existing air conditioning system. Many alternative solutions were evaluated by using computational fluid dynamics modelling. The best and applicable solution was selected and the existing ventilation system was modified. After implementing the new ventilation system, the hot environment was much improved. The temperature reduction in the curing process was about $6.4^{\circ}C$.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1899-1909
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• 2015

Glaucoma is one of the most common causes of blindness which is caused by increase of fluid pressure in the eye which damages the optic nerve and eventually causing vision loss. An automated technique to diagnose glaucoma disease can reduce the physicians’ effort in screening of Glaucoma in a person through the fundal retinal images. In this paper, optimal hyper analytic wavelet transform for Glaucoma detection technique from fundal retinal images is proposed. The optimal coefficients for transformation process are found out using the hybrid GSO-Cuckoo search algorithm. This technique consists of pre-processing module, optimal transformation module, feature extraction module and classification module. The implementation is carried out with MATLAB and the evaluation metrics employed are accuracy, sensitivity and specificity. Comparative analysis is carried out by comparing the hybrid GSO with the conventional GSO. The results reported in our paper show that the proposed technique has performed well and has achieved good evaluation metric values. Two 10- fold cross validated test runs are performed, yielding an average fitness of 91.13% and 96.2% accuracy with CGD-BPN (Conjugate Gradient Descent- Back Propagation Network) and Support Vector Machines (SVM) respectively. The techniques also gives high sensitivity and specificity values. The attained high evaluation metric values show the efficiency of detecting Glaucoma by the proposed technique.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.221-221
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• 2013

Vertical LED (VLED) has been recognized as a way to obtain the high-power LED due to their advantages [1]. However, approximately 4% of the light generated from the active region is extracted, if the light extraction from side walls and back side is neglected because of Fresnel reflection (FR) and total internal reflection (TIR) [2,3]. In this study, the optical simulation of the VLED with the various microstructures was performed. Among them, the microlens having the diameter of 3 ${\mu}m$ and the height of 1.5 ${\mu}m$ shown the best result was chosen, and then, optimized microlens was formed on a GaN template using conventional semiconductor process. Various microstructures were proposed to improve the light extraction efficiency (LEE) of the VLED for the simulation. The LEE was simulated using LightTools based on a Monte Carlo ray tracing. The microstructures with hemisphere, cone, truncated and cylinder pattern having diameter of 3 ${\mu}m$ were employed on the top layer of the VLED respectively. The improvement of the LEE by using the microstructure is 87% for the hemisphere, 77% for the cone, 53% for the truncated, 21% for the cylinder, compared with the LEE of the flat surface at the reflectance of 85%. The LEE was increased by 88% at the height of 1.5 ${\mu}m$, compared with the LEE of the flat surface. We found that the microlens on the top layer is the most suitable for increasing the LEE. In order to apply the proposed microlens on n-GaN surface, we fabricated microlens on a GaN template. A photoresist array having hexagonal-closed packed microlens was fabricated on the GaN template. Then, optimization of etching the GaN template was performed using a dry etching process with ICP-RIE. The dry etching carried out using a gas mixture of Cl2 and Ar, each having a flow rate of 16 sccm and 10 sccm, respectively with RF power of 50 W, ICP power of 900 W and chamber pressure of 2 mTorr was the optimum etching condition as shown in Fig. 2(a).

• 한국식품과학회지
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• 제31권4호
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• pp.1011-1016
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• 1999

식물의 세포벽 모형에 근거하여 고온고압의 조건하에서 기계적인 전단웅력을 식물 세포벽에 가할 경우 수용성 다당류를 효과적으로 분리할 수 있다는 가설에 근거하여 사과박으로부터 펙틴을 추출하기 위해 압출처리법을 도입하였다. L/D비가 20: 1인 동방향완전맞물림형 이축압출기를 이용하여 압출기의 축회전수, 원료의 공급률 및 원료의 수분함량을 공정변수로 하고 압출기의 비기계에너지를 시스템의 매개변수로 하여 압출처리에 의한 수용성 다당류의 수율, 평균 분자량 및 galacturonic acid 함량을 분석한 후, 각각의 모형을 개발하였다. 펙틴의 수율과 품질을 동시에 비교해 볼때, 비기계에너지를 증가시키면 펙틴의 수율이 향상되는 것으로 나타났으나, 수율을 향상시키는 압출조건은 품질의 저하를 초래하는 것으로 나타났다. 비기계에너지가 191 kWh/ton인 고강도의 추출조건에서 수율은 20.1%로 나타나 기존의 산처리법에 의한 14.4% 수율보다 월등히 향상된 수율을 얻을 수 있었다. 한편, 비기계에너지가 96 kWh/ton인 저강도의 추출조건에서는 분자량이 240,000인 펙틴을 얻을 수 있어 산처리시 분자량 181,000의 펙틴보다 훨씬 양질의 펙틴을 얻을 수 있었다. 따라서, 목표로 하는 품질의 펙틴을 생산할 수 있으면서 최고의 수율을 얻을 수 있는 압출조건을 설정해야 하며, 이를 위해서 본 연구에서 제시한 펙틴의 수율 및 품질 모형을 이용할 수 있다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 제5회 압출 및 인발가공 심포지엄
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• pp.43-49
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• 2002

A7003 alloy has characteristics of their excellent weldability, high corrosion resistance and superior plastic working however the broadening of application for the alloy has been hampered by the lower extrudability associated by Mg content. For improvement of extrudability and enhanced recovery efficiency during Al scrap recyeling, it has been generally practiced to reduce Mg content in A7003 alloy. Therefore, it is necessary to investigate the influence of Mg content on mechanical strength and extrudability of A7003 alloy. For efficient material processing which has small amounts, life cycle assessment in material processing(MLCA) is evaluated. The quantitative analysis of energy requirements and $CO_2$ emission for production of A7003 extruded bar are estimated with different Mg content and billet pre-heating process (heating source by light oil or LPG). In particular, the estimation of energy requirements was performed within shipping and gating range (except the mining and extraction stages)to investigate the influence of the variables on energy requirements and $CO_2$ emission in detail. As Mg content increased, the flow stress and the extrusion pressure for A7003 alloy increased. It has been thought that an increment in extrusion pressure with increasing Mg content is caused by the solid solution hardening of Mg atoms in the matrix and increment in volume fraction of intermetallic compound, $Mg_2Si$. The extrudability and the tensile strength are equal to, or above that of conventional A 7003 alloy even the content of Mg varied from $1.1wt.\%\;to\;0.5wt.\%$ alloy. This means that minimizing the content of Mg in A7003 alloy can enhance recovery efficiency during Al scrap recycling. It can be quoted that rather than Mg content energy source for billet heating is a prime factor to determine the atmospheric $CO_2$ emission.

• 한국식품저장유통학회지
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• 제17권5호
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• pp.757-761
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• 2010

자소는 여러 질환을 치료하는 식물로 알려져 있는데, 본 연구는 자소 추출물을 이용하여 항산화 활성 및 항염증 활성을 알아보았다. 자소 추출물을 이용한 DPPH, FRAP 실험 결과, 농도에 따른 항산화 활성을 확인할 수 있었으며, 자소자 추출물의 경우 고온/고압 추출시 활성이 증가하는 것을 알 수 있었다. 마우스 동물모델을 이용한 항아토피활성 결과 귀와 상피의 비후를 감소시키고, 면역세포의 침투현상을 억제하는 것으로 나타났다. 이상의 결과로, 자소는 항산화 및 염증완화 소재로 이용할 수 있음을 확인하였다.

• 자원리싸이클링
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• 제4권3호
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• pp.32-39
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• 1995

중유회의 소각재로부터 바나듐과 니켈을 회수할 목적으로 본 연구에서는 중유회 소각재의 물리 화학적 특성 및 침출특성을 조사하였다. 소각재의 물리 화학적 특성은 성분분석, 주사전자현미경에 의한 형태관찰 및 X선 회절실험을 통하여 조사하였고, 소각재중의 바나듐과 니켈의 침출특성은 물과 황산용액에 대하여 행하였다. 실험결과 중유회 소각재의 주요 구성물질은 $V_4$O, $V_2$O4, $NaVO_3$, $Ni_3$($VO_4$)$_2$, $Fe_2$$O_3$, $CaSO_4$, $SiO_2$로, 수용성 물질이 적어 수침출에 의해서는 소량의 바나듐만이 침출되었다. 한편, 황산침출이나 고온고압하에서의 황산침출은 중유회 소각재로부터 바나듐과 니켈을 추출하는데 효과적인 방법이었다. 황산침출의 경우(pH 0.5, 9$0^{\circ}C$) 바나듐과 니켈의 침출율은 각각 99%와 45%였고, 고온고압하의 황산침출의 경우 (pH 1.0, $200^{\circ}C$, 60 psi) 바나듐과 니켈의 침출율은 각각 86%와 75%를 나타내었다.