• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.63-63
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• 2000

Deep submicron device contact hole에서의 bottom step coverage의 향상 및 SALICIDE공정의 필요성에 의해 collimated sputtering 및 ionized sputtering 등의 다양한 증착방법이 연구되어왔다. 반도체소자의 고집적화 및 미세화에 따라서 기존의 증착방법보다 더 높은 throughput을 가진 새로운 증착방법의 필요성이 대두되고 있다. Collimated sputtering방식으로 증착한 박막의 경우에는 증착속도가 느리고 collimator의 사용기간에 따른 공정조건의 변화가 단점으로 작용하였고 새로이 ionzied sputtering방식이 개발되었다. ionzied sputtering방식은 증착되는 금속 입자를 이온화시키고 기판에 바이어스를 걸어서 증착되는 입자의 방향성 및 증착속도의 향상을 얻을 수 있었다. 하지만 고집적도가 더욱 증가함에 따라서 더 높은 박막의 증착속도, bottom step coverage의 향상, 방향성의 향상과 더불어 증착되는 입자의 이온화 율의 증가 및 기존의 증착방식에 의한 박막보다 향상된 물성을 가진 박막증착의 필요성에 의해 hollow cathode magnetron sputtering방식이 연구되었다. HCM방식으로 titanium 박막을 증착하여 collimated sputtering 및 ionize sputtering 방식으로 증착한 titanium 박막과 물성을 비교해서 증착방식에 따른 박막물성의 차이를 연구하였다. 증착전에 기판온도는 30$0^{\circ}C$를 유지하였고 base pressure는 5.0$\times$10-9torr, working pressure는 5.7m torr로 유지하였다. power는 30kW를 가하여 50nm두께의 titanium박막을 증착하였다. 증착된 박막의 미세구조는 TEM 및 XRD로 분석하였다. HCM방식으로 증착한 titanium박막은 5nm두께의 비정질 층이 관찰되었고 ionized sputtering방식으로 증착한 titatnium박막에서 나타나는 것으로 보고된 silicon (002)와 titanium (0002) eledtron diffraction spot사이의 (10-10)spot은 관찰되지 않았다. 박막은 크고 작은 grain의 연속적 분포를 가졌고 HCM방식으로 증착한 titanium박막의 in-plane grain size가 다른 증착방식으로 증착한 박막에 비해 크게 관찰됨을 Plan-view TEM 분석을 통해서 확인되었다.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.1
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• pp.51-60
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• 1999

An intermittently-aerated, intermittently-decanted single-reactor process (KIDEA process : KIST intermittently decanted extended aeration process) was applied for nitrogen removal from wastewater. Synthetic wastewater with chemical oxygen demand (COD): nitrogen (N) ratio of approximately 5.25: 1 was used. The average COD removal efficiency reached above 95%, and under optimal conditions nitrogen removal efficiency also reached above 90%. This process consisted of 72 minute aeration, 48 minute settling and 24 minute effluent decanting with continuous feeding of influent wastewater from the bottom of the reactor, and did not require a separate anoxic mixing-phase. In this process, nitritation ($1^{st}$ step of nitrification) was induced but nitratation($2^{nd}$ step of nitrification) was suppressed. Main factors responsible for the accumulation of nitrite ion in the experimental condition were free ammonium and dissolved oxygen. This condition of nitrite build-up accelerated by continuous feed flow in the bottom of the KIDEA reactor because of high concentration of ammonia nitrogen in the influent. This research provides one of answers to control nitrate build-up.

• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.1
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• pp.14-23
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• 2010

A numerical model was developed for simulating a three-dimensional multilayer hydrodynamic and thermodynamic model in domains with irregular bottom topography. The model was designed for examining the interactions between flow and topography. The model was based on the three-dimensional Navier-Stokes equations and was solved using the fractional step method, which combines the finite difference method in the horizontal plane and the finite element method in the vertical plane. The numerical techniques were described and the model test and application were presented. For the model application to the northern part of Ariake Sea, the hydrodynamic and thermodynamic results were predicted. The numerically predicted amplitudes and phase angles were well consistent with the field observations.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.363-366
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• 2004

PZT thin films were formed by rf-magnetron sputtering on $Pt/Ti/SiO_2/Si$ substrate. Bulk PZT target containing $5\%$ excess PbO was used. They were formed with in-situ process at $650^{\circ}C$ as total thickness of 175 and 250 nm after the depositing of thin PZT films at room temperature, i. e. 2-step Sputtering. It was found that the ferroelectric perovskite phase is formed at $650^{\circ}C$ by XRD and the interface between room temp.-layer and $650^{\circ}C$ -layer is not existent. In the samples undergoing 2-step sputtering the dielectric constant was 600 or more and the leakage current density was $2{\times}10^{-7}A/cm^2$. So, we found that the room temp.-layer on the bottom electrode stabilize the underlaid layers.

• Journal of the Korean Society of Combustion
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• v.7 no.3
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• pp.32-36
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• 2002

A numerical study was carried out to investigate combustion phenomena in a model Scramjet engine, which had been experimentally studied at the University of Tokyo using a high-enthalpy supersonic wind tunnel. The main airflow was Mach number 2.0 and the total temperature of hot flow was 1800K. Equivalence ratio was set to be 0.26 which is higher than that of experiment to investigate the effect of strong precombustion shock. The results showed that self-ignition occurred at the rear bottom wall of the combustor and combined with the shear layer flame between fuel jet and main airflow. Then, precombustion shock was generated at the step location and reversely enhanced the mixing and combustion process behind the shock. Due to the high equivalence ratio, the precombustion shock moved upstream of the step compared with that of experiment.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.127-132
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• 2001

A numerical study was carried out to investigate the combustion phenomena in a model Scramjet engine, which had been experimentally studied in the University of Tokyo using a high-enthalpy supersonic wind tunnel. The main airflow was 2.0 in Mach number and the total temperature of hot flow was 1800K. Equivalence ratio was set to be rather higher value of 0.26 than that of experiment to investigate the effect of strong precombustion shock. The results showed that self-ignition occurred at the rear bottom wall of the combustor and combined with the shear layer flame between fuel jet and main airflow. Then, precombustion shock was generated at the step location and reversely enhanced the mixing and combustion process behind the shock. Due to the high equivalence ratio, the precombustion shock moved upstream of the step compared with that of experiment.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.33-39
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• 2004

The performance of a deep water drillship, is investigated with the view of the characteristics of the thrusters and the resistance increasement due to moonpooi. The model tests have been performed to obtain the resistance of two drillships with the moonpooi open and closed including shape changes of moonpool step. To design the DP system, thrust forces of azimuth thrusters have been measured during azimuthing at zero speed condition. Thrusters, azimuthing under the bottom of ship, have the interactions of the other thrusters due to flow changes made by other thrusters, and the existence of ship hull makes the thrust deduction higher than when the thrust operates by itself. The resistance increasement due to the moonpooi is highly dependent on the step height of the moonpool and the draft. It is found that the height of moonpool step can reduce the resistance increasement by moonpool.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.112-116
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• 2017

Present study investigated the influence of time step size, turbulent eddy viscosity, and the number of layer on rapid and unsteady propagation of dam break flow. When the time step size had a value such that it resulted in Cr of 0.89, a significant numerical oscillation was observed in the vicinity of the wave front. Higher turbulent viscosity ensured smooth and mild slope of velocity and water stage compared with the flow behavior by no viscosity. The vertical velocity at the lower layer positioned near the bottom showed lower velocity compared with other layers.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.4
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• pp.59-63
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• 2013

In this paper, the impact of the copper densities of substrate layers on IC package warpage is studied experimentally and numerically. The substrate strips used in this study contained two metal layers, with the metal densities and patterns of these two layers varied to determine their impacts. Eight legs of substrate strips were prepared. Leg 1 to leg 5 were prepared with a HD (high density) type of strip and leg 6 to leg 8 were prepared with UHD (ultra high density) type of strip. The top copper metal layer was designed to feature meshed patterns and the bottom copper layer was designed to feature circular patterns. In order to consider the process factors, the warpage of the substrate bottom was measured step by step with the following manufacturing process: (a) bare substrate, (b) die attach, (c) applying mold compound (d) and post reflow. Furthermore, after the post reflow step, the substrate strips were diced to obtain unit packages and the warpage of the unit packages was measured to check the warpage trends and differences. The experimental results showed that the warpage trend is related to the copper densities. In addition to the experiments, a Finite Element Modeling (FEM) was used to simulate the warpage. The nonlinear material properties of mold compound, die attach, solder mask, and substrate core were included in the simulation. Through experiment and simulation, some observations were concluded.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.1
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• pp.111-119
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• 2015

The negative factors of fishery in environmental aspect of view are Greenhouse gas emission problems by high usage of fossil fuel, destruction of underwater ecosystem by bottom trawls, reduction of resources by fishing and damage of ecosystem diversity. Especially, the Greenhouse gas emission from fisheries is an important issue due to Canc$\acute{u}$n meeting, Mexico in 1992 and Kyoto protocol in 2005. However, the investigation on the GHG emissions from Korean fisheries did not much carry out. Therefore, the quantitative analysis of GHG emissions from Korean fishery industry is needed as a first step to find a relevant way to reduce GHG emissions from fisheries. The purpose of this research is to investigate which degree of GHG emitted from fishery. Here, we calculated the GHG emission from Korean bottom pair trawl fishery using the LCA (Life Cycle Assessment) method. The system boundary and input parameters for each process level are defined for LCA analysis. The fuel use coefficient of the fishery is also calculated. The GHG emissions from the representative fishes caught by bottom pair trawl will be dealt with. Furthermore, the GHG emissions for the edible weight of fishes are calculated with consideration to the different consuming areas and slaughtering process also. The results will be helpful to understand the circumstances of GHG emissions from Korean fisheries.