Advanced H2O2 oxidation for diethyl phthalate degradation in treated effluents: effect of nitrate on oxidation and a pilot-scale AOP operation

Ko, K. B.,Park, C. G.,Moon, T. H.,Ahn, Y. H.,Lee, J. K.,Ahn, K. H.,Park, J. H.,Yeom, I. T. IWA Publishing 2008 Water Science & Technology Vol.58 No.5

<P>One of the objectives of this study was to delineate the effect of nitrate on diethyl phthalate (DEP) oxidation by conducting a bench-scale ultraviolet (UV)/H2O2 and O3/H2O2 operations as suggested in a previous study. We also aim to investigate DEP oxidation at various UV doses and H2O2 concentrations by performing a pilot-scale advanced oxidation processes (AOP) system, into which a portion of the effluent from a pilot-scale membrane bioreactor (MBR) plant was pumped. In the bench-scale AOP operation, the O3 oxidation alone as well as the UV irradiation without H2O2 addition could be among the desirable alternatives for the efficient removal of DEP dissolved in aqueous solutions at a low DEP concentration range of 85±15 μg/L. The adverse effect in the UV/H2O2 process was significantly greater than that in the UV oxidation alone, and its oxidation was almost halved by the nitrate. However, the nitrate clearly enhanced the DEP oxidation in the O3 oxidation and O3/H2O2 process. Especially, the addition of nitrate almost doubled the DEP oxidation efficiency in the O3/H2O2 process. The series of pilot-scale AOP operations confirmed that about 30-50% of DEP dissolved in the treated MBR effluent streams was, at least, oxidized by the O3 oxidation alone as well as the UV irradiation without H2O2 addition. The UV photolysis of H2O2 was most effective for DEP degradation with an H2O2 concentration of 40 mg/L at a UV dose of 500 mJ/cm2.</P>

Formaldehyde 처리 귀리의 젖소 소화관내 영양소 분해율 측정

이상철(S . C . Lee),김병기(B . K . Kim),문여황(Y . H . Moon),문점동(C . D . Moon),안병홍(B . H . Ahn) 한국영양사료학회 1996 韓國營養飼料學會誌 Vol.20 No.1

유리系 內의 Ferrite의 Mossbauer Spectra

安振盛,金俊植,李敬行,趙壽烈,董徹,洪致裕 동국대학교 자연과학연구소 1984 자연과학연구 논문집 Vol.4 No.-

本 硏究는 5NiO-5CdO-10Fe₂O₃-30Na₂CO₃-10SiO₂(mole %)유리계에 대한 Mossbauer parameter의 溫度依存性을 조사하였다. Mossbauer spectrum은 한쌍의 Quadrupole doublet의 중첩으로 fitting하였으며 이중 하나는 tetrahedral site,다른 하나는 octahedral site이다. 상대적인 共鳴吸收面積比로부터 octahedral site와 tetrahedral site에 대한 Debye temperature를 계산하여 본 결과 각각 418K, 449K 임을 알았다. 또한 θ?값들을 이용해 least square method로 isomer shiftdral site의 壓力依存系數 α와 2.97×10?mm/sec K, I.S(0)일때의 를 평가해본 결과 octahedral site의 α는 2.97×10?mm/sec K,I.S(0)는 tetrahedral site이고 α의 3.2305×10?mm/sec K, I.S(0)는 0.276mm/sec임을 알았다. 그리고 quadrupole splitting은 측정온도가 증가함에 따라 서서히 감소함을 알았다. The temperature dependence of the Mossbauer parameter for 5NiO-5CdO-10Fe₂O₃-30Na₂CO₃-10SiO₂(mole %) quenched glass system was investigated. The spectra were fitted as superposition of a pair of quadrupole double ; One is for the tetrahedral site and the other is for the octahedral site. From the relative absorption area ratios of the spectra, the Debye erature of two sites were calculated to be 418K and 449K for the octahedral site and the ?edrai site, respectively. From these Debye temperatures, We can see that the isomer shifts and the coefficients αof the pressure dependence of the isomer shift are 0.456mm/sec, 2.97×10?mm/sec K for octahedral site and 0.276mm/sec K, 3.2305×10?mm/sec K for ?edral site. Also, we can see that the quadrupole splittings of two sites are gradually decresed the increase of the measuring temperature.

Group nearest-neighbor queries in the L₁ plane

Son, W.,Bae, S.W.,Ahn, H.K. North-Holland Pub. Co ; Elsevier Science Ltd 2015 Theoretical computer science Vol.592 No.-

<P>Let P be a set of n points in the plane. The k-nearest-neighbor (abbreviated as k-NN) query problem is to preprocess P into a data structure that quickly reports k closest points in P for a query point q. This paper addresses a generalization of the k-NN query problem to a query set Q of points, namely, the group k-nearest-neighbor query problem, in the L-1 plane. More precisely, a query is assigned with a set Q of at most m points and a positive integer k with k <= n, and the distance between a point p of P and a query set Q is defined as the sum of L-1 distances from p to all q is an element of Q. The maximum number m of query points Q is assumed to be known in advance and to be at most n. In this paper, we propose two algorithms, one based on the range tree and the other based on a data structure for segment dragging queries, and obtain the following complexity bounds: (1) a group k-NN query can be handled in O (T-min log n + (k + m(2))(log logn + logm)) time after preprocessing P using O(m(2)nlog(2)n) space, where T-min = min {k + m, m(2)}, or (2) a group k-NN query can be handled in O ((k + m)log(2) n + m(2)(log(is an element of) n + log m)) time after preprocessing P using O (m(2)n) space, where is an element of > 0 is an arbitrarily small constant. We also show that our approach can be applied to the weighted group k-nearest-neighbor query problem and the group k-farthest-neighbor query problem. (C) 2015 Elsevier B.V. All rights reserved.</P>

Covering a simple polygon by monotone directions

Ahn, H.K.,Brass, P.,Knauer, C.,Na, H.S.,Shin, C.S. Elsevier 2010 Computational Geometry Vol.43 No.5

In this paper we study the problem of finding a set of k directions for a given simple polygon P, such that for each point p@?P there is at least one direction in which the line through p intersects the polygon only once. For k=1, this is the classical problem of finding directions in which the polygon is monotone, and all such directions can be found in linear time for a simple n-gon. For k>1, this problem becomes much harder; we give an O(n<SUP>5</SUP>log<SUP>2</SUP>n)-time algorithm for k=2, and O(n<SUP>3k+1</SUP>logn)-time algorithm for fixed k>=3.

An assessment of axial pre-compression for the KSTAR central solenoid

Ahn, H.J.,Kim, H.T.,Kim, Y.O.,Chu, Y.,Park, H.K.,Park, K.R.,Oh, Y.K.,Kim, Y.S.,Han, D.W.,Kim, Y.H. Elsevier 2017 Fusion engineering and design Vol.124 No.-

<P><B>Abstract</B></P> <P>The central solenoid (CS) of the KSTAR consists of four pairs of superconducting coils compressed axially by preloading structures. The axial pre-compression is needed to suppress the maximum attractive or repulsive force of the coils based on reference operation scenarios. All CS coils were assembled with eight sets of preloading and supporting structures under precise dimensional control. Only shells of preloading structures were heated to make 6mm gap between the preloading structure and coil assembly. The gap was, then, filled up by wedge movement so that axial pre-compression be applied after thermal contraction of shells. However measured pre-compression is about 55% of the design value. A detailed investigation has been carried out to find reasons for the preloading reduction by comparing strain measurement and structural analysis results. The minimum residual compression is estimated as 6.5MN. It is expected to have no serious problem during large plasma current H-mode discharge with consideration of the anti-slip design. A structural analysis model of KSTAR CS magnet has been developed based on the measured strains during operations and will give a guide line for future high performance and long pulse operations of KSTAR.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A detailed investigation has been carried out to find reasons for the preloading reduction for KSTAR CS by comparing strain measurement and structural analysis results. </LI> <LI> A structural analysis model of KSTAR CS magnet has been developed based on the measured strains during operations. </LI> <LI> It is expected to have no serious problem during large plasma current H-mode discharge in future with consideration of the anti-slip design of each component. </LI> </UL> </P>

Y₂O₃ 첨가량에 의한 Al₂O₃ 복합재 세라믹스의 균열 치유와 고온 굽힘강도 특성

남기우(K. W. Nam),김해숙(H. S. Kim),손창석(C. S. Son),김성광(S. K. Kim),안석환(S. H. Ahn) 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.11

The four kinds of Al₂O₃ composite ceramics were prepared using a mixture of 85 wt.% Al₂O₃ (mean size 0.5 ㎛), 15 wt.% SiC powder with Y₂O₃ as an additive powder (0, 1, 3 and 5 wt.%). The crack-healing strengths were studied as functions of crack-healing temperature and amount of Y₂O₃. The in-situ crack-healing behavior was observed at 1,573 K for 1 h in the air. The heat treated specimen with 3 wt.% of Y₂O₃ showed better crack-healing ability than specimen with 1 or 5 wt.% of Y₂O₃. In case of specimen with 3 wt.% of Y₂O₃, the bending strength of the crack-healed specimen at 1,473 K was recovered to the bending strength of smooth specimen treated at 1573 K. The heat-resistance limit temperature of Al₂O₃ composite ceramics was 1,073 K, 1,373 K, 873 K for the specimen with 1, 3, 5 wt.% of Y₂O₃.

An improved data stream algorithm for clustering

Kim, S.S.,Ahn, H.K. Elsevier 2015 Computational Geometry Vol.48 No.9

In the k-center problem for streaming points in d-dimensional metric space, input points are given in a data stream and the goal is to find the k smallest congruent balls whose union covers all input points by examining them. In the single-pass streaming model, input points are allowed to be examined only once and the amount of space that can be used to store relative information is limited. In this paper, we present a single-pass, (1.8+ε)-factor, O(d/ε)-space data stream algorithm for the Euclidean 2-center problem for any d≥1. This is the first result with an approximation factor below 2 using O(d/ε) space for any d. Our algorithm naturally extends to the Euclidean k-center problem with k>2. We present a single-pass (1.8+ε)-factor data stream algorithm for the Euclidean k-center problem for any d≥1, which uses O(2<SUP>k</SUP>(k+3)!d/ε) space and O(2<SUP>k</SUP>(k+2)!d/ε) update time.

Al₂O₃ 복합 세라믹스의 고온 굽힘강도에 미치는 Y₂O₃의 영향

김해숙(H.S. Kim),안석환(S.H Ahn),손창석(C.S. Son),김종순(J.S. Kim),남기우(K.W Nam) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-

The four kinds of Al₂O₃ composite ceramics were prepared using a mixture of 85 wt.% Al₂O₃ (mean size 0,5 ㎛), 15 wt.% SiC powder with Y₂O₃ as an additive powder (0, 1, 3 and 5 wt.%), The crack-healing strengths were studied as functions of crack-healing temperature and amount of Y₂O₃. The in-situ crack-healing behavior was observed at 1,573 K for 1 h in the air. The heat treated specimen with 3 wt.% of Y₂O₃ showed better crack-healing ability than specimen with 1 or 5 wt.% of Y₂O₃. In case of specimen with 3 wt.% of Y₂O₃, the bending strength of the crack-healed specimen at 1,473 K was recovered to the bending strength of smooth specimen treated at 1573 K. The heat-resistance limit temperature of Al₂O₃ composite ceramics was 1,073 K, 1,373 K, 873 K for the specimen with 1, 3, 5 wt.% of Y₂O₃.

Effects of Egg Yolk Antibodies Produced in Response to Different Antigenic Fractions of E. coli O157:H7 on E. coli Suppression

Chae, H.S.,Singh, N.K.,Ahn, C.N.,Yoo, Y.M.,Jeong, S.G.,Ham, J.S.,Kim, D.W. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.11

The objective of this research was to provide the characterization and method for producing anti-E. coli O157:H7 antibodies in egg-laying hens and to determine if the antibody can restrain the proliferation of E. coli O157:H7 in-vitro. Selected antigenic fractions (whole cell, outer membrane protein and lipopolysaccharide (LPS)) from E. coli O157:H7 were injected to hens in order to produce anti-E. coli O157:H7 antibodies. The immune response and the egg yolk antibodies of laying hens against the whole cell, outer membrane protein and LPS antigens were monitored by ELISA. The level of antibodies against whole cell antigen monitored through ELISA sharply increased after the initial immunization, and it was found to be maximum on day 49 however, the level was maintained up to day 70. Antibodies (5 mg/ml) directed against the whole cell inhibited E. coli proliferation 10-13 times more than outer membrane protein or LPS. The antibody response against the whole cell antigens appeared to have higher activity in restraining the proliferation of E. coli O157:H7 than antibody against outer membrane protein or LPS. Results reflected that increasing the IgY's in the egg yolk could prevent greater economic losses due to human and animal health from pathogenic bacteria i.e. E. coli O157:H7.