• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.747-752
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• 2011

The parrotfish Oplegnathus fasciatus is a sub-tropical species that is difficult to culture during the winter in South Korea. As a result, a recirculating aquaculture system (RAS) was developed to rear parrotfish. This study investigated the effects of stocking density and dissolved oxygen (DO) concentration on the growth and hematology of the parrotfish in the RAS. The experimental stocking densities were 5 (SD05), 10 (SD10), 15 (SD15), and 20 kg/m3 (SD20) total body weight to tank water volume. As the stocking density increased, the mean weight gain, feed efficiency, and specific growth rate tended to decrease. However, SD10 and SD15 did not differ statistically from SD05 in feed efficiency (P>0.05). Although better growth was achieved in SD05, SD10 and SD15 appeared to be acceptable, practically and economically, in terms of feed efficiency. The experimental DO concentration ranges were 3-4 (DO3), 5-6 (DO5), and 7-8 mg/L (DO7). The mean weight gain and survival tended to increase with the DO concentration, but there were no differences among treatments (P>0.05). Although the feed efficiency did not differ among the treatments, the specific growth rates and daily feed intake increased with the DO concentration and were the highest in DO7 (P<0.05). The cortisol concentration was the highest in DO3 (P<0.05), while there was no difference between DO5 and DO7 (P>0.05).

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.355-358
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• 2002

In this study, we have tried to find the maximum microbial efficiency at the various dissolved oxygen (DO) concentration conditions in the treatment of pharmaceutical wastewater. Experiments of activated sludge process were performed to examine the relation between microbial activity and DO concentration in a continuous bioreactor. The reduction rate of COD (chemical oxygen demand) was low at the DO concentration between 0 ppm and 1.0 ppm, but it went higher and showed maximum between 1.5 ppm and 3.0 ppm. Then the COD reduction rate was quickly decreased above the DO concentration of 3.0 ppm.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.256-258
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• 2019

최근 MPEG-Immersive 표준화 그룹에서는 여러 위치에 존재하는 다수의 360 영상을 취득하고 처리하여 사용자에게 제한적인 화면 전환 이동에 따른 운동 시차(motion parallex)를 제공하는 3 degrees of freedom plus (3DoF+) 기술에 관한 표준화가 진행되고 있다. 이러한 3DoF+ 표준화 기술에서의 압축은 기존의 HEVC 코덱을 사용하나, 현재 존재하는 360 영상 사용자 시점 기반 스트리밍 기법을 3DoF+ 스트리밍에 적용하기 위해서는 기존의 360 영상과 다르게 영상 서로 간의 참조과정으로 인한 의존성으로 문제가 존재한다. 본 논문에서는 해당 문제점을 서술하고, MCTS(Motion-Constrained Tile Set)를 사용하여 보다 적은 디코더와 사용자 시점에 맞게 효율적으로 영상을 전송할 수 있는 MCTS 기반 타일 그룹 분할 방법을 제안한다.

• Journal of Korea Multimedia Society
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• v.15 no.6
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• pp.711-721
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• 2012

The objective of this study is to propose an efficient 3D reconstruction method for developing a stereo-vision-based haptics system which can replace "robotic eyes" and "robotic touch." The haptic rendering for 3D images requires to capture depth information and edge information of stereo images. This paper proposes the 3D reconstruction methods using LoG(Laplacian of Gaussian) algorithm and DoG(Difference of Gaussian) algorithm for edge detection in addition to the basic 3D depth extraction method for better haptic rendering. Also, some experiments are performed for evaluating the CPU time and the error rates of those methods. The experimental results lead us to conclude that the DoG method is more efficient for haptic rendering. This paper may contribute to investigate the effective methods for 3D image reconstruction such as in improving the performance of mobile patrol robots.

• Journal of Korean Society on Water Environment
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• v.31 no.2
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• pp.87-93
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• 2015

In this study, the inhibitory effect of toxic metals was investigated on the activated sludge of the municipal sewage treatment plant. The allowable concentration of toxic metals was also estimated for the stable operation of the biological treatment process. The single and mixture toxicity of $Cu^{2+}$, $Al^{3+}$ and $Zn^{2+}$ were evaluated for the activated sludge microorganisms. As a result, nitrifying microorganisms were more susceptible than heterotrophic microorganisms. $IC_{10}$ (Inhibition Concentration of 10%) of $Cu^{2+}$, $Al^{3+}$ and $Zn^{2+}$ for the nitrifying microorganisms was 3 mg/L, 7 mg/L and 25 mg/L, respectively. The mixture toxicity showed three times more sensitive than the single toxicity. The concentrations of $Cu^{2+}$, $Al^{3+}$ and $Zn^{2+}$ to minimize the inhibitory effect on organic matter removal and nitrification in batch experiments were found to be 1.3 mg/L, 2.5 mg/L and 6.3 mg/L.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.4
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• pp.519-526
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• 2006

In this study, the major operating factors in SND(simultaneous nitrification and denitrification) using bioreactor packed with submerged cilia media and granular sulfur such as variation of nitrification rate, organic matter removal efficiency and denitrification efficiency in different DO concentration were mainly evaluated. Synthetic wastewater and actual sewage were used as influent wastewater. Experiment with synthetic wastewater as influent wastewater was divided into three phases with the adjustment of DO concentration. As the results, nitrification efficiency and T-N removal efficiency in the Phase 3(DO 1.0~2.0 mg/L) were 99% and 52.3%, which is significantly greater than those in other two phases. Also, loading rate and denitrification efficiency of SCPGS(Submerged Cilia media Packed with Granular Sulfur) were calculated as $0.44kg\;NO_3^--N/m^3-day$ and 50%, respectively. On the other hand, nitrification rate was decreased from 99% to 64% according to the DO concentration with the variation from 3.0~3.5 mg/L(phase1) to 0.4~0.6mg/L(phase2). Although the nitrification rate was decreased in 64% according to the variation of the DO concentration, T-N removal rate was rapidly increased to 49% by increasing of the denitrification efficiency. Experiment with actual sewage as influent wastewater was carried out to evaluate efficiency of SCPGS in real operation condition of full-scale sewage water treatment plant. At the time, T-N removal rate in this experiment and full-scale wastewater treatment plants were given by 43% and 20%, respectively. The above results indicate that SCPGS can be used as an advanced treatment process for economical efficiency considered.

• The Journal of the Korean dental association
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• v.54 no.8
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• pp.613-629
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• 2016

This study assayed regional distribution of dental hospital & dental clinics, the number of population & households per one dental hospital & clinic, operation condition & duration. This study used public data that display from 1946 years(the first dental clinic open in republic of korea) to 2016 years. We collected present condition of 21,686 dental hospital and clinics available in public data portal site on 28. Feb.2016. Data were classified by scale, location, permission year, operation duration of dental hospital & clinics and were analyzed using SPSS 20.0 program. Surveyed on Feb. 2016. Best top 10 regions of permission dental clinics are (1) Gangnam-gu, Seoul(1,337), (2) Seongnamsi, Gyeonggi-do(555), (3) Songpa-gu, Seoul(491), (4) Yeongdeungpo-gu, Seoul(472), (5) Suwon-si, Gyeonggi-do(443), (6) Seocho-gu, Seoul(428), (7) Nowon-gu, Seoul(417), (8) Goyang-si, Gyeonggi-do(413), (9) Jung-gu, Seoul(380), (10) Yongin-si, Gyeonggi-do(353). Whereas best top 10 regions of operating dental clinics are (1) Gangnam-gu, Seoul(581), (2) Seongnamsi, Gyeonggi-do(415), (3) Suwon-si, Gyeonggi-do(382), (4) Seocho-gu, Seoul(320), (5) Changwon-si, Gyeongsangnam-do(303), (6) Songpa-gu, Seoul(295) (7) Goyang-si, Gyeonggi-do(290), (8) Bucheon-si and Yongin-si, Gyeonggi-do(262), (9) Jeonju-si, Jeollabuk-do(224). Average population per one dental hospital & clinic by regional local government are 3,120 people. Best five region of population per one dental hospital & clinic are (1) Sejong-si(5,272), (2) Gangwon-do(4,653), (3) Chungcheongbuk-do(4,513), (4) Gyeongsangbuk-do(4,490), (5) Chungcheongnam-do(4,402). Average households per one dental hospital & clinic by regional local government are 1,316 households. Best three region of households per one dental hospital & clinic are (1) Sejong-si(2,126), (2) Gangwon-do(2,057), (3) Gyeongsangbuk-do(1,946). From 1946 to 1986, permission and operating dental hospital and clinics was steadily increasing. On 1986-1990, 1991-1995, permission, operation and closure of dental hospital and clinics increase rapidly. From the 2011-2015 to 2016(present), permission, operation and closure of dental hospital and clinics is decreasing. Average operating duration of closured dental hospital and clinics are 14.054 years. We need to map of dental hospital and clinics for open and operation of one, base on analyzed results. In an era of 30,000 dentist, we should to be concerned about operation of dental clinics in the light of past operating condition.

• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.665-671
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• 2020

MPEG-I is actively working on standardization on the coding of immersive video which provides up to 6 degree of freedom (6DoF) in terms of viewpoint. 3DoF+ video, which provides motion parallax to omnidirectional view of 360 video, renders a view at any desired viewpoint using multiple view videos acquisitioned in a limited 3D space covered with upper body motion at a fixed position. The MPEG-I visual group is developing a test model called TMIV (Test Model for Immersive Video) in the process of development of the standard for 3DoF+ video coding. In the TMIV, the redundancy between a set of input view videos is removed, and several atlases are generated by packing patches including the remaining texture and depth regions into frames as compact as possible, and coded. This paper presents an atlas generation method that removes small-sized blocks in the atlas for more efficient 3DoF+ video coding. The proposed method shows a performance improvement of BD-rate bit savings of 0.7% and 1.4%, respectively, in natural and graphic sequences compared to TMIV.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.68-70
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• 2012

피쳐폰(Feature Phone)이 주를 이루던 초기 3G(Third Generation)는 사용자의 데이터 사용량이 많지 않았다. 그러나 스마트폰이 등장하면서 데이터를 이용한 서비스의 다양화, 저렴한 데이터 요금 정책으로 데이터 사용량이 대폭 증가하였다. 이동통신사가 예상하지 못한 데이터 사용량 증가로 3세대 망의 새로운 보안상 취약점이 나타났고 이를 이용한 DoS(Denial of Service) 공격이 발생하고 있다. 본 논문에서는 3세대 망에서 나타날 수 있는 DoS 공격의 하나인 DCH(Dedicated Channel) 고갈형 DoS 공격에 대한 논의하고 정상 사용자의 패킷 사용 패턴을 이용한 탐지 기법을 제안한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.431-431
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• 2016

J 호소는 1942년도에 충청남도 아산시 선장면에 설치된 농업용 저수지로서, 현재 COD, TN, TP 모두 등급외의 수질상태를 보이고 있다. J 호소 상류 유역은 축산농가가 다수 위치하고 있으며, 설치된 지 70년이 지난 노후화된 저수지로 고농도의 오염물질 유입뿐만 아니라 호소 바닥의 오염 퇴적물에 의한 내부 부하가 중요한 수질오염원이 되고 있다. 호소의 수질은 현재 COD 10.6~16.5 mg/L, Chl-a $75mg/m^3$ 이상으로 수질오염도가 매우 높으며, 특히 늦봄에서 초가을까지 외기온도 상승 및 저수율 저하와 함께 부영양화 증가, 녹조 대발생 등으로 호 내 물고기 대량 폐사 및 악취발생 등으로 민원이 다수 발생하고 있다. 이러한 현상의 직접적인 원인은 수중의 DO 농도 결핍이며, 따라서 수중의 DO 농도를 일정수준 이상으로 유지시켜 주는 것은 호소 수질관리를 위해 매우 필요하다고 판단된다. 본 연구에서는 공기 중의 산소를 호소 수체에 포기시켜 주는 마이크로버블 발생장치를 J 저수지에 설치하여 수체의 DO 농도 변화 등을 분석하였고, 본 연구결과는 농업용 호소의 수질개선을 위한 기술개발 및 계획수립의 기초자료로 활용하고자 하였다. 마이크로버블 포기장치는 수심이 약 4m 되는 저수지 제방 근처에 100m 간격으로 총 3지점에 설치하였다. 버블 발생기는 기액 2상류 선회형 마이크로 버블 발생장치로 3지점에 각 1set(1set에 3기로 구성)씩 구성하여 저수지 바닥 층에서 상부로 1m 떨어진 지점에 고정식으로 설치하였다. 총 공기흡입량은 380 LPM이며, 사용동력은 12.2kW를 사용하였다. 마이크로 버블 포기장치 설치 후 호 내 DO 농도 변화를 평가하기 위하여 호소 전체에 18개 지점을 선정하여 수심 50cm 간격으로 DO 농도를 측정하였다. 가동 전에는 DO 평균농도가 표층에서는 약 7.7mg/L로 나타났고, 수심에 따라 거의 수직적으로 감소하여 바닥층에서는 약 0.2mg/L로 거의 무산소 상태를 보이고 있었다. 마이크로 버블 가동 2주 후에는 수심 3m까지의 모든 수층에서 DO 농도가 약 6.0mg/L 이상을 보였고, 바닥층에서는 DO 약 3.4mg/의 농도를 나타내었다. 가동 3주 후에도 2주 후와 비슷한 수치를 보이고 있었으나 가동 4주가 지나면서부터는 호소 바닥층(수심 3.5m)에서도 DO 농도가 7.0mg/L 이상의 높은 농도를 유지하는 것으로 조사되었다. 호소 저층에서 호기성 상태의 지속적 유지는 퇴적 오염물질이 수층으로 용출되는 것을 예방할 수 있으므로 마이크로버블을 잘 활용하면 호소의 악취제거 및 수질개선에 많은 도움이 될 것으로 판단된다.