Effects of carbon to nitrogen ratio on the performance and stability of aerobic granular sludge

HyunGu Kim,JiTae Kim,DaeHee Ahn 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.1

The purpose of this study was to assess the nutrient salts removal efficiency and stability of the aerobic granular sludge (AGS) by change in C/N (carbon to nitrogen) ratio. The laboratory-scale experiments were performed to analyze the removal efficiencies for organic matter and contents of nitrogen, MLSS, sludge volume index, and extracellular polymeric substances (EPS) under C/N ratio conditions of 5.0, 10.0, 15.0, and 20.0. The microorganisms were observed using optical microscope and the microbial communities were analyzed using pyrosequencing. The increase in C/N ratio from 5.0 to 20.0 increased the organic matter and nitrogen removal efficiency to 95.9 and 79.1%, respectively. For the EPS contents, an influencing factor of granule stability, the polysaccharides to protein (PS/PN) ratio increased from 0.55 to 0.79. For the microbial community, the Thauera was the most common genus in ending phase occupying 63.7%. This microorganism is regarded as one contributing to organic matter degradation and improved production of EPS including AGS of microorganism, thus, may be an explanation of the results of this study such as increase in organic material in AGS and improvement of denitrification efficiency and contents of EPS with increase in C/N ratio.

Impact ionization and tunneling operations in charge-plasma dopingless device

Kim, Minsuk,Kim, Yoonjoong,Lim, Doohyeok,Woo, Sola,Im, Kyeungmin,Cho, Jinsun,Kang, Hyungu,Kim, Sangsig Elsevier 2017 Superlattices and microstructures Vol.111 No.-

<P><B>Abstract</B></P> <P>In this paper, we present the impact ionization and tunneling operations in a newly designed dopingless device. Our proposed device functions selectively—as either a <I>p</I>-channel impact-ionization MOSFET (<I>p</I>-IMOS) or an <I>n</I>-channel tunneling field-effect transistor (<I>n</I>-TFET)—according to the bias conditions. To realize the dopingless device, the charge-plasma effect is employed to induce <I>n</I>- or <I>p</I>-type regions without any doping process, by choosing an electrode metal with an appropriate work function. The band diagrams, <I>I–V</I> characteristics, subthreshold swings (<I>SS</I>), and carrier-concentration profiles of the device under the <I>p</I>-IMOS and <I>n</I>-TFET operation modes are analyzed in our study, using a commercial device simulator. The device yields an extremely low <I>SS</I> of 0.53 mV/dec under the <I>p</I>-IMOS operation mode. It also exhibits a low off-current of approximately 10<SUP>−14</SUP> A/μm and a high <I>I</I> <SUB>ON</SUB>/<I>I</I> <SUB>OFF</SUB> of approximately 10<SUP>8</SUP>, under the <I>n</I>-TFET operation mode.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A charge-plasma effect is employed to realize our newly designed dopingless device. </LI> <LI> The single dopingless device possesses both <I>p</I>-IMOS and <I>n</I>-TFET characteristics. </LI> <LI> Without any doping, the device can act similar to a conventional doped device. </LI> </UL> </P>

The effects of high salinity on nitrogen removal and the formation characteristics of aerobic granular sludge

HyunGu Kim,DaeHee Ahn 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.5

Thermal and electrical conductivity of Al(OH)3 covered graphene oxide nanosheet/epoxy composites

Kim, Jiwon,Im, Hyungu,Kim, Jong-min,Kim, Jooheon Springer-Verlag 2012 JOURNAL OF MATERIALS SCIENCE - Vol.47 No.3

Performance of ring oscillators composed of gate-all-around FETs with varying numbers of nanowire channels using TCAD simulation

Kim, Sutae,Kim, Minsuk,Woo, Sola,Kang, Hyungu,Kim, Sangsig Elsevier 2018 Current Applied Physics Vol.18 No.3

<P>In this paper, we investigate the performance of ring oscillators composed of gate-all-around (GAA) silicon nanowire (NW) field-effect transistors (FETs) with four different numbers of NW channels, for sub-10-nm logic applications. Our simulations reveal that ring oscillators with double, triple, and quadruple NW channels exhibit improvements of up to 50%, 85%, and 97%, respectively, in the oscillation frequencies (f(osc)), compared to a ring oscillator with a single NW channel, due to the large drive current, in spite of the increased intrinsic capacitance of a given device. Moreover, our work shows that the f(osc) improvement ratio of the ring oscillators becomes saturated with triple NW channels with additional load capacitances of 0.1 fF and 0.01 fF, which are similar to, or less than the intrinsic device capacitance (similar to 0.1 fF). Thus, our study provides an insight for determining the capacitive load and optimal number of NW channels, for device development and circuit design of GAA NW FETs. (C) 2017 Elsevier B.V. All rights reserved.</P>

소독부산물 제어를 위한 자연유기물(NOM) 제거와 고도정수처리공정 적용에 관한 연구

김현구 ( Hyungu Kim ),엄한기 ( Hanki Eom ),이동호 ( Dongho Lee ),주현종 ( Hyunjong Joo ) 한국물환경학회 2015 한국물환경학회지 Vol.31 No.5

Natural Organic Matter (NOM) is a precursor of disinfection by products. Recently, with the increase in NOM concentration caused by a large amount of algae, the creation of disinfection by-products is becoming a big issue. Therefore, in this study, PAC+Membrane+F/A hybrid process was organized to control disinfection by-products in small-scale water treatment plants. The optimal dosage of PAC was set at 20 mg/L through Lab. scale test. Also, it is judged that NOM concentration must be less than 1.0 mg/L to meet the recommended criteria of drinking water quality monitoring items of disinfection by-products during chlorination. The existing conventional water treatment process was compared to the independent F/A process and the PAC +Membrane+F/A hybrid process through pilot plant operation, and the result showed that there is a need to apply an advanced water treatment process to remove not only NOMs but also Geosmin caused by algae. Accordingly, it is considered that applying the PAC+Membrane+F/A process will help in controling a clogged filter caused by a large amount of algae and disinfection by-products created by chlorination and can be used as an advanced water treatment process to meet the recommended criteria of drinking water quality monitoring items.

중관학파의 학파적 특징과 티베트에서의 전개

김현구(Kim Hyungu) 보조사상연구원 2012 보조사상 Vol.37 No.-

티베트 불교사 전전기에 나타나고 있는 중관학파는 경중관과 유가행중관파로만 분류된다. 후전기의 티베트 종의논사들은 짠드라끼르띠의 중관사상을 기준으로 인도 중관사상을 다시 해석하며, 이것이 티베트 불교사의 전환점이 된다. 이 과정에서 자립논증파와 귀류논증파라는 학파명이 등장한다. 특히 쫑카빠는 귀류논증파를 불교 최고의견해로 정립한다. 이 과정이 쫑카빠의 『정리대해』와 『의취선명』에서 자립논증파와 귀류논증파의 학파적 특징과 차이로 나타나고 있다. 쫑카빠 이후의 종의문헌가들은 쫑카빠의 정의에 따라 중관학파 가운데에서 귀류논증의 관점을 가장 높은 사상체계로 평가한다. 그러나 실제 인도 중관학파에서 쫑카빠가 강조하고 있는 것과 같은 자립논증파와 귀류논증파 사이의 대립 구도가 나타나지 않고 있다. 오히려 유식학파와 중관학파라는 대립 구도를 바탕으로 학파적 독립성을 강화하고 있는 측면이 『입중론』에서 제시되고 있다. 그것은 유식학파를 하위의 종의로 내세우려는 중관학파의 요의ㆍ불요의설로 나타나고 있다. 이 글에서는 바비베카와 짠드라끼르띠의 교판 형식의 ‘공통점’을 고찰하면서 자립논증파와 귀류논증파의 원형적 모습을 추적하였다. 요의ㆍ불요의에 바탕한 교판 형식은 티베트에서 자립논증파와 귀류논증파가 등장하기 이전 인도 중관학파에서 나타나고 있는 학파적 특징이다. Yeshe sde, the first Tibetan doxographer in the eight-century, esteems the Yogācāra-Madhyamaka synthesis created by Śāntarakṣita and Kamalaśila as the highest Buddhist school of thought. Bhāviveka’s Sautrāntika-Madhyamaka is ranked second. Candrakīrti is not mentioned. The Indian and Tibetan evidence point to an eleventh-century resurrection of Candrakīrti’s writings in India and a twelfth-century birth of the Prāsaṅgika movement in Tibet. In the Tibetan Buddhist history of later diffusion(phyi dar), Tibetan Buddhist interpret of the idea of India Madhyamaka based on Candrakīrti’ views. It is a turning point in Tibetan Buddhist history, because it changes India Madhyamaka synthesis. In this process, the school name of Svātantrika and Prāsaṅgika appeared. Especially, the interpretation of Tsong kha pa serves a status of Prāsaṅgika as the highiest view of Buddhism. Tsong kha pa defines the difference and characteristics between Svātantrika and Prāsaṅgika on Tsa ba’i shes rab ces bya ba’i rnam bshad rigs pa’i rgya mtsho and dGong pa rab gsel. After Tsong kha pa’ definition, Tibetan doxographies esteem Prāsaṅgika as the highest Buddhist school of thought among the India Madhyamaka. However, the India Madhyamaka was originated from the debate with the Vijānavādin. Because it appears to build into Vijānavādin as subdivision of the India Madhyamaka. In this article, I examine the ’common things’ with Bhāviveka and Candrakīrti’s type of doctrin. To do this, I show that it’s origins and characteristics as a prototype of Madhyamaka before the emergence of Svātantrika and Prāsaṅgika in Tibet.

복합재료의 낙추 시뮬레이션 정합성 개선 방안 연구

김원희(Wonhee Kim),김종찬(Jongchan Kim),지현구(HyunGu Ji),장우영(Wooyeong Jang) 한국자동차공학회 2019 한국자동차공학회 학술대회 및 전시회 Vol.2019 No.11

차선유지지원장치(LKAS) 성능검증을 위한 평가시나리오 항목 설정과 분석

김경진(Kyungjin Kim),우현구(Hyungu Woo),용부중(Boojoong Yong),김성섭(Sung-sub Kim),임재환(Jae-Hwan Lim) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5

FLOW-3D를 이용한 자연형 어도 수리학적 특성 분석

정석일 ( Seokil Jeong ),송현구 ( Hyungu Song ),김지성 ( Jisung Kim ),김원장 ( Wonjang Kim ),김재옥 ( Jaeok Kim ) 한국농공학회 2013 한국농공학회 학술대회초록집 Vol.2013 No.-

하천 횡단 수공구조물인 보나 낙차공은 구조물 상ㆍ하류 생태계의 단절을 발생시켜 회귀성 어류 등 하천 생물의 생존을 위협하고 있기 때문에, 최근 하천 설계는 자연형 하천조성사업과 같이 하천의 치수 및 이수뿐만 아니라 생태학적인 면까지 고려하기 위하여 많은 노력을 하고 있다. 이러한 노력의 일환으로 본 연구에서는 자연형 어도를 설계하였고, FLOW-3D를 이용하여 수리학적인 특성을 분석하였다. 그림 1과 그림 2는 본 연구에서 설계한 어도의 형상으로 사행횟수를 다르게 하여 Type-I(사행 1번)과 Type-II(사행 3번)로 나누었다. 어도는 격벽 구간(A구간)과 콘크리트기둥 구간(B구간)으로 나뉘며, 총 길이는 200 m이다. A구간과 B구간의 바닥은 모래와 콘크리트이며, 이를 재현하기 위해 조도계수를 각각 다르게 하여 수치모의를 수행하였다. 수치모의는 평시를 가정하였으며, 수치모의 시간은 1,500초로 정상상태에 도달하였다. 그림 2와 3은 수치모의 결과로 Type 1과 Type 2의 B부분에서 국부적인 차이를 보이지만 전체적으로 유사한 흐름특성을 보이는 것으로 나타났다. A-03과 B-03부분을 제외한 전 구간에서 1.0 m/sec 이하의 유속이 발생하여 어류의 돌진속도와 비교하였을 때, 이동하는 것에는 큰 무리가 없는 것으로 나타났으며, A-03과 B-03 경계부근에서는 유속이 약 2.0 m/sec 으로 상대적으로 크게 발생하였지만, 격벽의 크기를 줄여 통수단면적을 크게 해 주거나, A-03 말단의 수위와 B-03 유입부 수위의 차이를 줄여준다면 충분히 어도의 기능을 수행할 것으로 판단된다.