• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.402-407
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• 2008

Recent popularity in mobile electronics requires higher standard on the mechanical strength of electronic packaging. Thus, the method of soldering between chip and substrate in electronic packaging process is changing from conventional method using intermetallic compound to a new method using organic solderability preservative (OSP) in order to improve the stability and the reliability of final product. Since current organic solder preservatives have several serious problems like thermo-stability during packaging process, however, it is necessary to develop new OSPs having thermo-stability. The main purpose of this study is to investigate the effect of MeOH/IPA (Isopropyl alcohol) ratio on the fluxing of a new OSP, developed in previous research, andto find out an optimum formulation of flux components for the application of the OSP in current packaging process. As a result of this study, it was revealed that higher MeOH/IPA ratio in flux showed better performance of fluxing a new OSP.

• KSBB Journal
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• v.10 no.1
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• pp.1-8
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• 1995

A lot of water soluble proteins and lipids are released from minced mackerel meat and lost into the washing waste during the leaching process of Kamaboko or surimi manufacture. The removed proteins and lipids are not only an edible things but also a big burden for treating the wastewater. In order to recover the proteins from the effluent and to use as food stuff, the "pH-shifting" treatment, a modified isoelectric point precipitation method, was tried. This method is based on a myogen-aggregation phenomenon, which occurs when a solution of sarcoplasmic proteins is acidified or alkalified beyond the critical pH zone of 2∼3 or 12∼13 respectively and then neutralized. The maximum amount of precipitation was obtained by shifting the pH of the wastewater from original pH to isoelectric point (pH 4) or alkali pH 12 and then changing to neutral pH. The precipitates were easily collected by filteration or centrifuging at 10,000rpm. The oils which were only floating in the washing wastewater are easily recovered by seperating with oil separator after pouring. The recovered proteins were slightly denaturated during this pH shifting precipitation process, while the composition of amino acids was good balance as a food.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.194-200
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• 2017

On-site Algae Collecting System (OACS) is one of urgent countermeasures to clean the raw water when the algae blooms severely. Rapid reaction capability, high efficiency and large capacity are required when applying OACS to large water areas. The total performance of OACS are always determined by unit process named Flotation, Trapping and Collection. The working efficiency and daily treatment quantity of OACS can be increased when it runs automatically. As the rapid development of OACS technology, in the first place, equipment are miniaturized and simple. And in the second place, automation process from Trapping to Collection are advanced. So, They produce results higher working efficiency, smaller residual sludge on treated water, system's advanced environmental friendly features and the increased amount of sludge by Collection process to achieve large capacity. Now OACS has overcome the algae multiplication rate to ensured the amount of removal algae. In another aspect, it is high economically feasible because of reducing operation cost against the large capacity.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.3
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• pp.76-89
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• 2014

The functions of urban park including health related benefit and climate adaptation and mitigation are expanding. However, in-depth research and discourse on the equitable distribution of expanded park function has been limited so far. Following research suggests Green Welfare concept to reflect distributive equity and multifunctionality in the process of urban park policy development and execution. This study developed park welfare indices to analyze disparities of neighborhood urban park(NUP) distribution viewed from green welfare by literature review. The findings analyzed through the Correlation Analysis and Cluster Analysis by SPSS 18.0. The results of the study are as follows. First, green welfare is defined as "to receive equitable benefits and participate in the delivery process of green services which are promoting health and securing safety from climate change risks for every citizen by life cycle regardless of socioeconomic status". Second, NUP per person in Seoul indicate meaningful differences by socioeconomic and environmental status of Seoul administrative districts. Park welfare indices correlated to NUP per person were shown population density(negative), percentage of individuals $aged{\geq}65$(positive), percentage of self-reliance of local finance(positive), flood and air pollution vulnerability by climate change(negative). Third, the cluster analysis identifies three significant clusters that indicate differences of park welfare level. Thus, it was found that NUP in Seoul from a green welfare perspective was provided disproportionately. Future urban park policy in Seoul was required equitable distribution of multifunctionality of park beyond quantitative expansion, and priority consideration should be given to park service consumer.

• Clean Technology
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• v.20 no.3
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• pp.218-225
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• 2014

Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. In this work, the gasification behavior of ash-free coal (AFC) was compared with that of the parent raw coal. In order to modify the gasification conditions, the raw coal gasified with fixed variables (water supply, space velocity, temperature, catalysts) in a fixed bed reactor. When catalysts are added by physical mixing method with coal, $K_2CO_3$ was the most effective additives for steam gasification of coal. However, the activity of ash-free coal (AFC) was much less reactive than raw coal due to high temperature extraction in a 1-methylnaphthalene under 30bar at $370^{\circ}C$ for 1 h, almost removed oxygen functional groups, and increased carbonization. The addition of $K_2CO_3$ in AFC achieved higher conversion rate at low temperature ($700^{\circ}C$). At that time, the molar ratio of gases ($H_2/CO$ and $CO_2/CO$) was increased because of water-gas shift reaction (WGSR) by addition of catalysts. This shows that catalytic steam gasification of AFCs is achievable for economic improvement of gasification process at mild temperature.

• Korean Journal of Food Science and Technology
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• v.47 no.4
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• pp.460-467
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• 2015

Sea urchin roe obtained from Anthocidaris crassispina and Pseudocentrotus depressus was briefly salt-fermented (5%), followed by ethanol treatment (1%) and the physicochemical properties as well as antioxidant activity were investigated. Compared to raw sea urchin roes, the salted one showed a significantly low amount of water (p<0.001) high salinity (p<0.05), ash content (p<0.001) and Na content (p<0.001). With salt-fermentation, the redness (p<0.05) and yellowness (p<0.001) of roe decreased noticeably, indicating the decomposition of endogenous carotenoids. Accordingly, the salted roe showed a lower DPPH radical scavenging activity than its unsalted counterpart. Additionally, it showed a significantly lower metal-chelating activity (p<0.05) and metal chelator content (e.g. ortho-phenolics) displayed by a negligible difference in titratable acidity. The salted roe showed significantly increased hardness (p<0.05) and total reducing capacity (p<0.001), which were attributed to the protein coagulation and the release of antioxidants bound to macromolecules after the ethanol treatment, respectively.

• Clean Technology
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• v.10 no.2
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• pp.61-72
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• 2004

In this study, aqueous/semi-aqueous cleaning agents which consist of organic solvent, surfactant, cosurfactant, and water were developed by changing formulation parameters such as organic solvent type and contents, surfactant type and contents, and cosurfactant/surfactant(A/S) ratio, etc.. And physical properties and flux removal of the formulated cleaning agents have been evaluated. Also, the performance of oil-water separation from the rinse water contaminated during the cleaning process was evaluated for its recycling. The formulated cleaning agents in this work expected to have good penetration because of their low viscosity and low surface tension values of 30.2~32.5 dyne/cm. The flux removal with the terpene type cleaning agent was higher than that with hydrocarbon type cleaning agent and two commercial products (CPA(commercial product A), CPB(commercial product B)). And the performance of oil-water separation by gravity settling from the rinse water contaminated with formulated cleaning agent and soils was shown to be very good. The cleaning agents developed in this work were applied to surface mounting technology(SMT) cleaning process for manufacturing electronic parts at L electronic company. As a result, the newly developed cleaning agents showed two times better cleaning speed for removal of solder cream than the conventional ond containing ethanol and IPA(isopropyl alcohol). In addition, malodor and VOC problems generated by the previous organic cleaning agents have been solved in the manufacturing field through introduction of the non-volatile and environmental-friendly cleaning agents to the field.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.168-168
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• 2012

Al doped ZnO (AZO)는 태양전지, 평판 디스플레이, OELD 등 광전자 소자에 적용되는 투명전도막용 재료인 ITO의 대체 재료로서 최근에 가장 각광받고 있는 물질이다. 하지만, $2.5{\times}10^{-4}{\Omega}{\cdot}cm$의 낮은 비저항과 90% 이상의 투과도를 갖는 ITO의 비해 AZO의 특성은 아직 부족한 상황이다. 수십 년간 많은 연구자들에 의해 다양한 제조 방법과 공정 조건들로 전기적, 광학적 특성을 향상시키기 위한 노력들이 진행되어 왔다. 하지만 실리콘 반도체와는 달리 II-VI족 물질의 정확한 근본적인 원리는 아직 불분명한 상태이다. 지금까지 AZO의 특성 향상의 원인을 결정립 크기, 주상구조의 우선 방위, 결정성, Zn-O 구조내의 산소 결핍 등의 메커니즘으로 설명해 왔다. 하지만, 본 연구에서는 지금까지 제안된 상기 요인의 변화 없이 전기적, 광학적 특성을 향상시키는 것이 짧은 열처리만으로도 가능했다. AZO 박막의 전기적, 광학적 특성에 큰 영향을 미치는 보다 근본적인 원인은 도핑 효율이다. ZnO 내에 도핑된 Al의 양보다 실제로로 활성화된 Al의 비율을 올리는 것이 중요하다. 본 연구에서 구조적, 조성적 변화 없이 도핑효율을 8.9%에서 66.7%까지 증가시켰으며, 이동도는 박막 표면의 및 결정립계 사이의 과잉산소를 줄임으로서 optical phonon scattering 감소를 통하여 증가시킬 수 있고, 이러한 과잉산소의 감소는 deep level emission을 감소시킴으로서 투과도 증가에도 영향을 준다. 본 연구에서 짧은 열처리를 통해 구조적 변화 없이 도핑효율의 증가만으로 $4.8{\times}10^{-4}{\Omega}{\cdot}cm$의 비저항과 90%의 투과도를 갖는 AZO 박막을 제조하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.223.1-223.1
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• 2015

본 연구에서는 지름이 다른 두 개의 디스크가 적층된 구조를 갖는 금 나노 구조체를 제작하고 그 광학적 특성에 대해 연구하였다. 나노임프린팅을 통하여 패턴된 폴리머 포어 어레이에 금 박막을 증착하고, 포어 내부에 증착된 금 나노구조체를 선택적으로 수거하는 방법을 이용하였다 [1]. 특히 금 증착 시, 빗각으로 증착 (oblique-angle deposition)을 하여 지름이 다른 두 개의 디스크가 적층되어 있는 구조를 형성하는 것이 가능하였다. 증착 각도의 조절을 통해 적층된 두 디스크의 지름 비율을 변화시킬 뿐만 아니라, 2차원 디스크 형태의 나노구조체부터 3차원 디쉬 형태의 구조체도 제작이 가능함을 확인하였다. 제안된 하향식 나노공정을 통하여 합성된 금 나노구조체를 이용하여 광열 전환(photothermal heat conversion)과 광 간섭성 단층 (optical coherence tomography) 측정을 진행하였고, 서로 다른 두 개의 디스크가 적층된 형태의 금 나노구조체는 상용 금 나노로드 (Au nanorod) 보다 높은 광 열 전환 효율을 갖을 뿐 아니라 우수한 OCT 이미징 특성을 보였다. 광열 전환 및 OCT 이미징 실험 결과는 각각 플라즈모닉 나노구조의 광흡수, 광산란 특성에 기반하므로, 본 연구를 통하여 제안된 금 나노구조체는 광흡수 및 광산란을 기반한 바이오이미징 나노프로브로 유용하게 사용될 수 있을 것으로 전망된다.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.807-809
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• 2009

Thin film deposition methods have been widely used and intensively investigated because high quality crystalline films enable to fabricate by sputtering. Especially rf magnetron sputtering deposition has advantages of being employ a relatively high deposition rate and also to achieve high crystalline films in low pressure because plasma density around target by magnetic is high. To apply ZnO thin film for SAW filter, it has highly flat surface, excellent c-axis preferred orientation and high resistivity value. As-deposited ZnO films showed the strong c-axis growth and excellent crystallinity. C-axis preferred orientation, resistivity and surface roughness highly depended on oxygen/argon gas ratio.