• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.220-227
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• 2000

The purpose of this study is to develop the non-gravity fluidized dryer. In this non-gravity fluidized dryer the fluidized zone is produced by two paddles in mixer, which maximizes the surface area of materials and then heated air through the guiding panels dehumidify them. This can conduct the drying process quickly and control moisture contents to lower limits. The ventilation system is closed loop system, which can be changeable to open system, and can be used as a multi-purposed dryer in which mixing, drying, granulating and cooling process is conducted. In order to develop non-gravity fluidized dryer, in the first the fundamental experiments performed to mixing accuracy and then the other parts of dryer and control system were examined to check whether they were designed properly and operated harmoniously with mixer. Also the preparatory experiments were fulfilled to examine the efficiency and reliability of dryer. Lastly, on the basis of preparatory experiments in case the initial moisture contents, desired moisture contents, heated air velocity and heating temperature were vary, performance test for the non-gravity fluidized dryer carried out.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.867-869
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• 1999

In this study, $SrBi_{2}Ta_{2}O_{9}$(SBT) thin films were etched as a function of $SF_6$/Ar gas mixing ratio in magnetically enhanced inductively coupled plasma(MEICP) system fer a fixed rf power, dc-bias voltage, and chamber pressure. The etch rate of SBT thin film was $1500{\AA}/min$ and the selectivities of photoresist (PR) and $SiO_2$ to SBT thin film were 0.48 and 0.62, respectively when the samples were etched at a rf power of 600W, a dc-bias voltage of -150V, a chamber pressure of 10 mTorr and a gas mixing ratio of $SF_6/(SF_6+A)$=0.1. In order to examine the chemical reactions on the etched surface, X-ray photoelectron spectroscopy(XPS) and secondary ion mass spectrometry(SIMS) were done.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.30-39
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• 2001

The direct injection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced by the high pressure injector is of paramount importance in DISI(Direct Injection Spark Ignition) engines in that the primary atomization process must meet the requirement of quick and complete evaporation, mixing with air and combustion especially to prohibit the excessive HC emissions. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the DISI engine. The direct Mie scattered and shadowgraph images presented the macroscopic view of the liquid sprays and vapor fields. The velocity and particle size of fuel droplets were investigated by phase doppler anenometer(PDA) system. The processes of atomization and evaporation with a DISI injector were observed and consequently utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.56-63
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• 2003

Micro/nano adhesion and friction properties of mixed self-assembled monolayer (SAM) with different chain length for MEMS application were experimentally studied. Many kinds of SAM having different spacer chains(C6, C10 and C18) and their mixtures (1:1) were deposited onto Si-wafer, where the deposited SAM resulted in the hydrophobic nature. The adhesion and friction properties between tip and SAM surfaces under nano scale applied load were measured using an atomic force microscope (AFM) and micro scale applied load were measured using ball-on-flat type micro-tribotester. Surface roughness and water wetting angles were measured with SPM (scanning probe microscope) and contact anglemeter. Results showed that wetting angles of mixed SAMs showed the similar value of pure SAMs. The coating surface morphology was increased as mixing of SAM. Nano adhesion and nano friction decreased as increasing of the spacer chain length and mixing of SAM. Micro friction was decreased as increasing of the spacer chain, but micro friction of mixed SAM showed the value between pure SAMs. Nano adhesion and friction mechanism of mixed SAM was proposed in a view of stiffness of spacer chain modified chemically and topographically.

• Advances in environmental research
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• 제1권2호
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• pp.125-142
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• 2012

Clean development mechanism (CDM) validity study was conducted to suggest better and more adaptable CDM scenario on water treatment plant (WTP). Potential four scenarios for CDM project; improvement of intake pumping efficiency, hydro power plant construction, solar panel construction and system optimization of mechanical mixing process were evaluated on S-WTP in Korea. Net present value (NPV) of each scenario was estimated based on sensitivity analysis with the variable factors to investigate the CDM validity percentile. Hydro power plant construction was the best option for CDM business with 97.76% validity and $1,127,069 mean profit by 9,813 $tonsCO_2e$/yr reduction. CDM validity on improvement of intake pumping efficiency was 90.2% with $124,305 mean profit by huge amount of $CO_2$ mitigation (10,347 $tonsCO_2e$/yr). System optimization of mechanical mixing process reduced 15% of energy consumption (3,184 $tonsCO_2e$/yr) and its CDM validity and mean profit was 77.25% and $23,942, respectively. Solar panel construction could make the effect of 14,094 $tonsCO_2$ mitigation annually and its CDM validity and mean profit was 64.68% and $228,487, respectively.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.861-866
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• 2004

A numerical flow analysis has been performed on the partial admission turbine of KARI turbopump to support the aerodynamic and structural dynamic assessments. The flow-field in a partial admission turbine is essentially three dimensional and unsteady because of a tip clearance and a finite number of nozzles. Therefore the mixing plane method is generally not appropriate. To avoid heavy computational load due to an unsteady three dimensional calculation, a frozen rotor method was implemented in steady calculation. It adopted a rotating frame in the grid block of a rotor blade by adding some source terms in governing equations. Its results were compared with a mixing plane method. The frozen rotor method can detect the variation of flow-field dependent upon the blade's circumferential position relative to the nozzle. It gives a idea of wake loss mechanism starting from the lip of a nozzle. This wake loss was assumed to be one of the most difficult issues in turbine designers. Thus, the frozen rotor approach has proven to be an efficient and robust tool in design of a partial admission turbine.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.25-28
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• 2000

In this study, $Y_2$O$_3$ thin films were etched with inductively coupled plasma (ICP). The etch rate of $Y_2$O$_3$, and the selectivity of $Y_2$O$_3$ to YMnO$_3$ were investigated by varying Cl$_2$/(Cl$_2$+Ar) gas mixing ratio. The maximum etch rate of $Y_2$O$_3$, and the selectivity Of $Y_2$O$_3$ to YMnO$_3$ were 302/min, and 2.4 at Cl$_2$/(Cl$_2$+Ar) gas mixing ratio of 0.2 repectively. In x-ray photoelectron spectroscopy (XPS) analysis, $Y_2$O$_3$ thin film was dominantly etched by Ar ion bombardment, and was assisted by chemical reaction of Cl radical. These results were confirmed by secondary ion mass spectroscopy(SIMS) analysis. YCI, and YCl$_3$ existed at 126.03 a.m.u, and 192.3 a.m.u, respectively

• 펄프종이기술
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• 제33권3호
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• pp.1-8
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• 2001

Paper consists of fiber network and paper properties were highly affected by fiber characteristics. Many researchers have tried to relate fiber and paper properties. Softwood and hardwood fiber's are quite different in their properties. Generally, softwood fiber's are longer and more flexible than hardwood fibers. At present, many paper mills make mixed paper with softwood and hardwood fibers except for special grade. During fracture some fiber's are broken and others are pulled out. In this paper, the number of broken and pulled out fiber's during fracture is analyzed depending on the mixing ratio of softwood and hardwood fiber's. Fiber length, curl, kink, coarseness, WRV and formation index were measured. Double-edged strength samples were prepared to observe the number of broken and pulled out fiber's. Mixed paper strength was decreased with increasing hardwood fibers ratio. During fracture, softwood fiber's were more likely broken and hardwood fibers were more likely pulled out. The strength of paper which consists of softwood fibers was determined by fiber's broken strength and that of hardwood fibers by fiber's debonding strength. Paper strength was changed depending on the fiber's bonding capability. If the fiber is longer and more flexible, the fiber network becomes stronger and stiffer.

• 한국융합학회논문지
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• 제9권11호
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• pp.75-81
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• 2018

블록체인 내의 모든 트랜잭션이 공개되기 때문에 익명성과 프라이버시 문제는 중요해지고 있다. 공개 블록체인은 사용자 대신 공개키 주소를 사용하여 익명성을 보장하는 것처럼 보이지만 트랜잭션 그래프를 기반으로 다양한 기법을 통해 추적함으로써 익명성을 약화시킬 수 있다. 본 논문에서는 블록체인 환경에서 익명성과 프라이버스를 보호하기 위하여 다양한 보안 기법을 융합하여 사용자의 추적을 어렵게 하는 기법을 제안한다. 제안 기법은 k-anonymity 기술, 믹싱 기술, 은닉서명, 다단계 기법, 램덤 선택기법, 영지식 증명 기법 등을 융합하여 인센티브 및 기여자의 참여를 통해 익명성과 프라이버시를 보호한다. 성능 분석을 통해 제안기법은 기여자의 수가 공모자의 수보다 많은 환경에서는 공모를 통한 프라이버시 및 익명성 훼손이 어렵다는 것을 보였다.

• 한국산림과학회지
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• 제96권5호
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• pp.561-566
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• 2007

This study was conducted to clarify runoff production processes in forested catchment through hydrograph separation using three-component mixing model based on the End Member Mixing Analysis (EMMA) model. The study area is located in the coniferous-forested experimental catchment, Gwangneung Gyeonggido near Seoul, Korea (N 37 45', E 127 09'). This catchment is covered by Pinus Korainensis and Abies holophylla planted at stocking rate of 3,000 trees $ha^{-1}$ in 1976. Thinning and pruning were carried out two times in the spring of 1996 and 2004 respectively. We monitored 8 successive events during the periods from June 15 to September 15, 2005. Throughfall, soil water and groundwater were sampled by the bulk sampler. Stream water was sampled every 2-hour through ISCO automatic sampler for 48 hours. The geochemical tracers were determined in the result of principal components analysis. The concentrations of $SO_4{^{2-}$ and $Na^+$ for stream water almost were distributed within the bivariate plot of the end members; throughfall, soil water and groundwater. Average contributions of throughfall, soil water and groundwater on producing stream flow for 8 events were 17%, 25% and 58% respectively. The amount of antecedent precipitation (AAP) plays an important role in determining which end members prevail during the event. It was found that ground water contributed more to produce storm runoff in the event of a small AAP compared with the event of a large AAP. On the other hand, rain water showed opposite tendency to ground water. Rain water in storm runoff may be produced by saturation overland flow occurring in the areas where soil moisture content is near saturation. AAP controls the producing mechanism for storm runoff whether surface or subsurface flow prevails.