저탁도시 PAC와 Ca-PAX의 입자제거 및 슬러지 탈수성 비교

심유섭,유명진,조희경,이상수,곽종운 대한상하수도학회 2002 상하수도학회지 Vol.16 No.4

This study was accomplished to evaluate the characteristics of particle removal and sludge dewatering and to find out the optimal condition of coagulation depending on the dosage of different coagulants (PAC, Ca-PAX) in low turbidity water. The experiments were carried out at a pilot plant of conventional rapid sand filtration system using artificial raw water. There was no large difference in the removal efficiencies of turbidity and total particle counts for both coagulants. However, Ca-PAX was required less than PAC to obtain the same efficiency of removal, and the initial head loss in a filter increased more fastly in case of PAC. The results on the evaluation of sludge from settling tank indicated that specific resistance of sludge was decreased inversely to the dose of both coagulant and specific resistance of Ca-PAX sludge was lower than that of PAC, therefore dewatering of sludge in case of Ca-PAX was better.

메셀로스폐액의 주입율에 따른 2단탈질공정의 질소 제거

정창화,심유섭,김성준,박철휘 대한상하수도학회 2003 상하수도학회지 Vol.17 No.6

The purpose of this study was to develop a solution to reduce the cost of methanol as external carbon source. The raw water of J-S.T.P. contains low concentration of readily biodegradable organics and high concentration of nitrogen due to the influents of industrial wastewater and leachate. Consequently, the influent C/N ratio is very low, and thus the supplemental addition of methanol is required to provide external carbon source for denitrification. Pilot plant experiments composed 2-stage denitrification process were performed to examine the effects and performances of the selected carbon source and the operation conditions for applications in practice. When the same amount of denitrifying substrates based on denitrification rate of methanol were injected, the effluent T-N concentration of using mecellulose wastewater was similar to that of methanol. Comparing the influent concentration of carbon source and the denitrification rate, it was shown that the denitrifying potential of mecellulose wastewater was 60% and injecting 1/3 of carbon source into the preanoxic tank was appropriate to ensure the stabilized effluent water quality. The COD,, requirement of mecellulose wastewater per nitrogen removed was 1.4 times of the required amount for methanol, and the settlability of sludge treated with mecellulose wastewater improved about 29%, which confirmed its potential as effective external carbon source.

X-선 회절법에 의한 소결광내의 칼슘페라이트 생성에 미치는 Al_2O_3, SiO_2 및 MgO의 영향

朴埈賢,趙兪貞,尹晟燮,許完旭,金亨順 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.7

In order to elucidate the fundamental aspects of the minerals formation processes during sintering, the Fe_2O_3-CaO-Al_2O_3-SiO_2 system and the effect of MgO on synthesized iron ore sinter were studied by image analysis and X-ray diffraction method. Most existed calcium ferrite was identified to be a solid solution of CaO·2Fe_2O_3 with a small amount of solubility of Al_2O_3 and SiO_2. With an increase of the content of Al_2O_3 in the system, the amount of calcium ferrite was increased. On the other hand, the amount of calcium ferrite was decreased, and the amount of hematite was increased with increasing the content of SiO_2. Crystal structure of calcium ferrite with Al_2O_3 and SiO_2 was changed from monoclinic to triclinic as well as the unit cell volume shrank with fixing Al_2O_3 and increasing SiO_2. With increasing the content of MgO(1∼3 wt%), the amount of magnetite was increased and hematite was decreased but calcium ferrite was not changed.

GPS-X 시뮬레이션을 이용한 2단탈질 공정에서 외부탄소원 적용성 평가

정창화,심유섭,김태형,박철휘 대한상하수도학회 2004 상하수도학회지 Vol.18 No.1

The purpose of this study was to evaluate adaptability of external carbon source using GPS-X program in pilot plant composed with 2-stage denitrification process. The result from analysis of pilot plant operation and GPS-X simulation showed that effluent concentration could be simulated similarly by modifying operation conditions, such as DO concentration, C/N ratio and other calibrated parameter. In order to satisfy the standard of the effluent water quality on T-N of 20㎎/L, it required approximately 3.1 of C/N ratio and 50% of nitrogen removal efficiency when influent T-N is 36.9㎎/L. To maintain the stable water quality of the receiving water, the effluent T-N concentration should be less than 10-15㎎/L and the appropriate C/N ratio to remove nitrogen was 4.27-6.82. The analysis of sensitivity to kinetic coefficient and reaction constant showed that Y_(H) and μ_(mAUT) were most sensitive to nitrate and ammonia nitrogen, relatively and sensitivity coefficient of their were 1.32, 1.98. It was concluded that as Y_(H) decreased and μ_(mAUT) increased, the reaction rates of denitrification and nitrification increased and the removal efficiencies of NO₃^(-)-N and NH₄^(+)-N improved.

Characteristic Analysis on Axial Flux Permanent Magnet Synchronous Generator Considering Wind Turbine Characteristics According to Wind Speed for Small-Scale Power Application

Yu-Seop Park,Seok-Myeong Jang,Ji-Hwan Choi,Jang-Young Choi,Dae-Joon You IEEE 2012 IEEE transactions on magnetics Vol.48 No.11

<P>To use a permanent magnet (PM) synchronous generator to wind power generation systems, the wind turbine characteristics according to wind speed should be considered in the design stage and performance evaluation. Using the wind turbine characteristics provided by a manufacturer, we predict the performance of a wind power generator that uses an axial flux PM by analyzing the electromagnetic field characteristics. To avoid the long analysis time required by the three-dimensional finite element method because of the structural features of axial flux PM machines, an alternative analytical approach is presented, and its results are validated experimentally. In addition, we present an AC-DC-DC converter that is connected to the experimental setup for back-to-back tests in order to obtain constant output regardless of wind speed variations.</P>

Exploring Multiple Biomarker Combination by Logistic Regression for Early Screening of Ovarian Cancer

Yu-Seop Kim,Min-Ki Jang,Chan-Young Park,Hye-Jeong Song,Jong-Dae Kim 보안공학연구지원센터 2013 International Journal of Bio-Science and Bio-Techn Vol.5 No.2

Analytic Modeling of a Depletion-Mode Cylindrical Surrounding-Gate Nanowire Field-Effect Transistor

Yu, Yun Seop,Park, Hyung-Kun American Scientific Publishers 2012 Journal of nanoscience and nanotechnology Vol.12 No.7

<P>A compact model for depletion-mode p-type cylindrical surrounding-gate nanowire field-effect transistors (SGNWFETs) is proposed. The SGNWFET model consists of two back-to-back Schottky diodes for the metal-semiconductor (MS) contacts and the intrinsic SGNWFET. Based on the electrostatic method, the intrinsic SGNWFET model was derived from current conduction mechanisms attributed to bulk charges through the center neutral region, in addition to accumulation charges through the surface accumulation region. The authors' previously developed Schottky diode model was used for the M-S contacts. The new model was applied to an advanced design system (ADS), whereby the intrinsic part of the SGNWFET and the Schottky diode were developed using the Verilog-A language. The results of the simulation of the newly developed SGNWFET model reproduced the experiment results considerably well.</P>

Explicit continuous current-voltage (I-V) models for fully-depleted surrounding-gate MOSFETs (SGMOSFETs) with a finite doping body.

Yu, Yun Seop,Cho, Namki,Oh, Jung Hyun,Hwang, Sung Woo,Ahn, Doyeol American Scientific Publishers 2010 Journal of nanoscience and nanotechnology Vol.10 No.5

<P>An analytical and continuous dc model for cylindrical doped surrounding-gate MOSFETs (SGMOSFETs) in the fully-depleted regime is presented. Starting from Poisson's equation, an implicit charge equation is derived approximately by a superposition principle with the exact channel potential and the charge equations in the depletion approximation. Also, a new explicit charge equation is derived from the implicit charge equation. The current equations without any charge-sheet approximation are based on the implicit and explicit charge control models, and both of them are valid for all the operation regions (linear, saturation, and subthreshold) and traces the transition between them without any fitting parameters. In the case of the SGMOSFETs with the fully-depleted condition, both of results simulated from the SGMOSFET models reproduce various 3D simulation results within 5% errors.</P>

Electromagnetic Field Characteristic Analysis and Comparison of Slotless Permanent Magnet Synchronous Generators with Grid Connection

Yu-Seop Park 한국자기학회 2018 Journal of Magnetics Vol.23 No.2

This paper deals with the characteristic analysis of permanent magnet (PM) wind power generators according to stator winding topology to compare the machine performance, and the experimentally measured current with grid connection is employed for the investigation. The analysis models dealt with in this study have the slotless structure in their stator core to eliminate the cogging torque with the identical PM rotor, and three coil winding types according to coil pitch and winding types are addressed for their comparison. One of the analysis models is manufactured to be integrated with a grid-connected power converter, and the measured phase current of the generator is applied to investigate their flux density, resulting radial force and power loss characteristics of each analysis model. For the reasonable comparison, the generators have very similar equivalent circuit parameters, such as induced voltage and resistance, so the load voltage and current characteristics are almost identical. From the results dealt with in this study, one of the analysis models is proposed to be applied for the small-scale wind power generation systems.

Characteristic Analysis and Comparative Investigation on Permanent Magnet Synchronous Machines considering Operating Conditions

Yu-Seop Park 한국자기학회 2017 Journal of Magnetics Vol.22 No.4

This paper deals with the comparative investigation on an interior permanent magnet synchronous machine (IPMSM) and a surface-mounted permanent magnet synchronous machine (SPMSM) considering operating conditions, and finite element method (FEM) is employed to analyze their electromagnetic field characteristics. For the reasonable comparison, those machines have identical machine size and equivalent circuit parameters, such as induced voltage and resistance, and one of the analysis models is manufactured for the experimental verification. From the no-load and load test, the induced voltage and phase current are measured, and the validity of analysis results are demonstrated by showing well corresponded results. In addition, since the phase current contains harmonic components, they are considered in the power loss characteristic analysis by considering operating conditions to investigate their influence on machine performance. In this study, the SPMSM shows relatively better core loss and rotor loss characteristics compared to IPMSM when the machines are operated in high rotational speed condition.