울릉(사동)항 2단계 동방파제 축조공사 중 해성퇴적모래층 강도정수 평가

김홍석,김철환,하태균,김래현,Kim, Hong-Seok,Kim, Cheol-Hwan,Ha, Tae-Gyun,Kim, Rae-Hyeon 한국지반공학회 2014 지반 : 한국지반공학회지 Vol.30 No.7

하폐수의 재사용 및 방류를 위한 폭기조 내 표준산소전달 효율 모니터링 시스템에 관한 연구

김홍석,김용범,고경한,김상우,심환보,Kim, Hong-Seok,Kim, Yong-Beom,Ko, Kyung-Han,Kim, Sang-Woo,Shim, Hwan-bo 한국자원리싸이클링학회 2019 資源 리싸이클링 Vol.28 No.6

본 연구에서는 활성 슬러지 하수처리장에서 배출되는 off-gas에 대한 포집 및 측정 모니터링을 통해 폭기조의 산소전달효율을 측정하고 청수와 비교하여 시스템의 신뢰성을 검증하는 연구를 수행하였다. 먼저, 청수를 기반으로 용존산소, 산소전달계수 및 표준산소전달효율을 측정하였으며 각각 8.60 mg/L, 9.49/hr, 23.96%의 값이 얻어졌다. 한편, 하수처리장 현장에서 진행한 off-gas 시험 결과 표준산소전달효율이 22.81%로 계산되어 청수와의 차이가 거의 없는 것으로 나타났다. 이는 현장에 설치된 산기관의 성능 및 폭기조의 상황을 모니터링 시스템을 이용해 실시간으로 확인함으로써 신뢰성있는 데이터를 확보할 수 있음을 의미한다.

4- 비닐시클로헥센을 이용한 방향족 니트로 화합물의 환원반응

김홍석,김동일,김청식,주영제 ( Hong Seok Kim,Dong Il Kim,Cheong Sig Kim,Young Je Joo ) 한국공업화학회 1994 공업화학 Vol.5 No.5

부타디엔의 고분자반응 또는 운반 및 보관과정에서 이량화되어 생성되는 4-비닐시클로헥센(VCH)을 이용하여 방향족 니트로화합물을 Pd/C 촉매하에서 촉매 전달 수소화반응시켜 높은 수율의 아닐린유도체로 합성하였다. 니트로벤젠고리에 치환기가 치환된 오르토-니트로톨루엔, 오르토-니트로페놀, 오르토-니트로아니졸의 경우는 파라-니트로톨루엔, 파라-니트로페놀, 파라-니트로아니졸의 반응보다 반응 소요시간이 길었다. 4-비닐시클로헥센-에탄올-Pd/C계에서 오르토, 메타, 파라-클로로니트로벤젠, 파라-니트로벤즈알데히드, 파라-니트로벤질알코올, 파라-니트로벤질 아세테이트 등의 화합물에서는 환원반응뿐만 아니라 가수소 분해반응도 진행되어 파라-톨루이딘이 생성되었다. Most of the aromatic nitro compounds were reduced to amines in high yield by transfer of hydrogen from 4-vinyl cyclohexene to the substrate via palladium catalyst. The usefulness of the method is not affected by the presence of a variety of other functional groups such as -OH, -OCH₃, -CH₃, -CO₂H, and -Cl, except for halogen which is removed during hydrogenation. The reduction of ortho-substituted nitrobenzene such as o-nitrotoluene, o-nitrophenol, o-nitroanisole was slower than the para isomer. Typically, the nitro compound is refluxed in ethanol with a large exess of 4-vinylcyclohexene in the presence of Pd-C catalyst. Under the above conditions, p-nitrobenzaldehyde, p-nitrobenzyl alcohol, and p-nitrobenzyl acetate were reduced to p-toluidine.

포밀벤조일디아조메탄과 티오펜유도체의 로듐촉매반응

김홍석,김상화,김동일,Kim, Hong Seok,Kim, Sang Hwa,Kim, Dong Il 대한화학회 1996 대한화학회지 Vol.40 No.6

비구면 인공수정체와 구면 인공수정체의 술 후 구면수차, 고위수차 및 대비감도의 비교

김홍석,김상우,하병진,김응권,김태임,Hong Seok Kim,Sang Woo Kim,Byung Jin Ha,Eung Kweon Kim,Tae-im Kim 대한안과학회 2008 대한안과학회지 Vol.49 No.8

Purpose: To compare spherical aberration, higher-order aberration, and contrast sensitivity of eyes implanted with aspheric (AcrySof IQ) or spherical (AcrySof Natural) intraocular lenses. Method: Seventy-five eyes implanted with posterior chamber intraocular lenses were divided into two groups: AcrySof IQ (35 eyes) and AcrySof Natural (40 eyes). Wavefront analysis (spherical, higher-order and total aberration) using iTace, and contrast sensitivity (under photopic and mesopic condition) using Optec 6500 were performed at 1 month and 3 months postoperatively. Result: One month after surgery, the IQ IOL (intraocular lens) group had lower values of spherical aberration (p<0.001) and higher-order aberration (p=0.048) than the Natural IOL group. The IQ IOL group also showed better contrast sensitivities at 1.5- and 3-cpd spatial frequencies in mesopic conditions. Three months after surgery, the IQ IOL group had less spherical aberration (p<0.001) and higher-order aberration (p=0.027) than the Natural IOL group and showed better contrast sensitivities at the 3-cpd spatial frequency in mesopic conditions. Conclusions: Aspheric AcrySof IQ IOL induced significantly less higher-order aberration and spherical aberration than AcrySof Natural IOL. The contrast sensitivity was better under mesopic conditions in the AcrySof IQ IOL-implanted group. J Korean Ophthalmol Soc 49(8):1256-1262, 2008

시멘트와 Fe(II)을 이용한 환원성 탈염소화반응의 유효반응성분 규명

김홍석,이유정,김하얀,황인성,Kim, Hong-Seok,Lee, Yu-Jung,Kim, Ha-Yan,Hwang, In-Seong 한국지하수토양환경학회 2006 지하수토양환경 Vol.11 No.6

본 연구는 시멘트/Fe(II) 시스템에서 TCE의 환원성 탈염소화에 관여하는 유효반응성분을 규명하기 위하여 수행되었다. 먼저 시멘트 자체에 존재하거나 혹은 그 수화물에 존재하는 성분을 다량 함유하고 있는 hematite(${\alpha}-Fe_2O_3$), lepidocrocite(${\gamma}$-FeOOH), akaganeite(${\beta}$-FeOOH), ettringite($Ca_6Al_2(SO_4)_3(OH)_{12}$)를 대상으로 TCE 분해실험을 수행하여 이러한 물질이 시멘트/Fe(II) 시스템에서 탈염소반응에 관여할 수 있는지 고찰한 결과, hematite가 잠재적 유효반응성분으로 선정되었다. 각 시스템의 반응속도상수를 비교해 본 결과 200 mM Fe(II)에 hematite와 CaO를 1 : 4(몰비)로 주입한 시스템($k\;=\;0.637\;day^{-1}$)이 기존의 cement와 Fe(II)을 이용한 경우($k\;=\;0.645\;day^{-1}$)와 가장 비슷한 동력학적 분해경향을 보인다는 것을 알 수 있었다. 처음에 pH 조절이 주목적으로 주입되었던 CaO 역시 분해반응에서 중요한 역할을 담당하는 것으로 나타났는데, CaO 첨가량이 증가할수록 hematite/CaO/Fe(II) 시스템의 분해능은 증가하다가 CaO 양이 일정 수준에 다다르면 증가세가 둔화되는 경향을 보여 주었다. SEM(Scanning Electron Microscopy) 분석을 통해서는 hematite/CaO/Fe(II) 시스템 내에서 분해능이 커질수록 육각형 판상의 결정이 새롭게 형성된다는 것을 확인 할 수 있었으며 이 결정은 portlandite, green rust($SO_4$), Friedel's salt 등일 가능성이 높은 것으로 판단되었다. 그리고 동일 시료의 XRD(X-Ray Diffraction) 분석을 통해서는 hematite, magnetite/maghemite, green rust($SO_4$)의 존재를 확인할 수 있었다. SEM 및 XRD 분석에서 공통적으로 나타나는 green rust($SO_4$)가 유효반응성분일 가능성이 높다고 판단되었다. Experimental study was conducted to identify the active agent for reductive dechlorination of TCE in cement/Fe(II) systems. Several potential materials-hematite (${\alpha}-Fe_2O_3$), lepidocrocite (${\gamma}$-FeOOH), akaganeite (${\beta}$-FeOOH), ettringite ($Ca_6Al_2(SO_4)_3(OH)_{12}$)-that are cement components or parts of cement hydrates were tested if they could act as reducing agents by conducting TCE degradation experiments. From the initial degradation experiments, hematite was selected as a potential active agent. The pseudo-first-order degradation rate constant ($k\;=\;0.637\;day^{-1}$) for the system containing 200 mM Fe(II), hematite and CaO was close to that ($k\;=\;0.645\;day^{-1}$) obtained from the system containing cement and 200 mM Fe(II). CaO, which was originally added to simulate pH of the cement/Fe(II) system, was found to play an important role in degradation reactions. The reactivity of the hematite/CaO/Fe(II) system initially increased with increase of CaO dosage. However, the tendency declined in the higher CaO dosage region, implying a saturation type of behavior. The SEM analysis revealed that the hexagonal plane-shaped crystals were formed during the reaction with increasing degradation efficiency, which was brought about by increasing the CaO dosage. It was suspected that the crystals could be portlandite or green rust ($SO_4$) or Friedel's salt. The XRD analysis of the same sample identified the peaks of hematite, magnetite/maghemite, green rust ($SO_4$). Either instrumental analysis predicted the presence of the green rust ($SO_4$). Therefore, the green rust ($SO_4$) would potentially be a reactive agent for reductive dechlorination in cement/Fe(II) systems.

경유자동차 질소산화물 저감을 위한 Urea-SCR 기술 현황

김홍석,조규백,정용일,Kim, Hong-Seok,Jo, Gyu-Baek,Jeong, Yong-Il 재료연구소 2008 機械와 材料 Vol.19 No.4

시멘트/Fe(II) 및 hematite/Fe(II) 시스템의 TCE 분해반응 시 Ca 성분의 영향

김홍석,황경엽,안준영,이주영,황인성,Kim, Hong-Seok,Hwang, Kyung-Yup,Ahn, Jun-Young,Yi, Jou-Young,Hwang, In-Seong 한국지하수토양환경학회 2011 지하수토양환경 Vol.16 No.1

Reactive reductants of cement/Fe(II) systems in dechlorinating chlorinated hydrocarbons have not been identified. The previous studies showed that a hematite/CaO/Fe(II) system had TCE degradation characteristics similar to those of cement/Fe(II) systems with regard to degradation kinetics and that lime (CaO) plays an important role in enhancing the reactivity for TCE dechlorination. The current study shows identified the formation of gypsum ($CaSO_4$) in the hematite/CaO/$FeSO_4$ system through the XRD analysis. The amounts of the gypsum increased with increment of the initial CaO dose. However, when CaO in the hematite/CaO/$FeSO_4$ system was replaced with gypsum, TCE degradation was not observed. Ca-removed Portland cement extracts (CPCX) in combination with $FeSO_4(CPCX/FeSO_4)$ showed no TCE degradation. On the other hands, the Portland cement extracts (PCX) in the presence of $FeSO_4(PCX/FeSO_4)$ and CPCX/CaO/$FeSO_4$ systems degraded 0.2 mM TCE within 5 days, indicating that CaO also played an important role dechlorination reactions in the systems. The pseudo-first-order rate constants (k) of the CPCX/CaO/$FeSO_4$ systems were 0.20, 0.24, and 0.72 $day^{-1}$, when the CaO dosages were 25, 50 and 75 g/L, respectively. The XRD analyses showed identified the common peaks having the d-values of 3.02, 2.27, and 1.87 in the reaction systems that showed TCE degradation. However, it was not possible to clearly identify the crystalline minerals having the three peaks from the references in JCPDS cards. This study reveals that the reactive agents in the cement/Fe(II) and the hematite/Fe(II) systems are likely to be those containing CaO and Fe(II).

Ammonium Ion Binding Property of Naphtho-Crown Ethers Containing Thiazole as Sub-Cyclic Unit

김홍석,Kyung Soon Do,Ki Soo Kim,심준호,차근식,남학현 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.10

디젤 엔진 분무의 액적 미립화 모델 및 벽면 충돌 모델에 관한 연구

김홍석,성낙원,Kim, Hongsuk,Sung, Nakwon 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.1

In this research computational methods for the droplet atomization and spray wall impingement are studied for the non-evaporating diesel fuel spray. The TAB(Taylor Analogy Breakup) model and Wave model are compared with experiments in order to describe droplet atomization process. The Watkins model and O'Rourke model are compared to simulate the spray wall impingement. As a result, It is found that the application of the Wave model has a good agreement with the experimental data in the case of high pressure injection. With regard to wall Impingement phenomena, it is found that the Watkins model is appropriate to the high temperature cylinder wall condition, while the O'Rourke model is appropriate to cold starting problem.