• 한국환경과학회지
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• 제18권4호
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• pp.445-450
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• 2009

In this study, the fundamental experiments were performed for catalytic oxidation of NO (50 ppm) on $MnO_2$ in the presence of ozone. The experiments were carried out at various catalytic temperatures ($30-120^{\circ}C$) and ozone concentrations (50-150 ppm) to investigate the behavior of NO oxidation. The honeycomb type $MnO_2$ catalyst was rectangular with a cell density of 300 cells per square inch. Due to $O_3$ injection, NO reacted with $O_3$ to form $NO_2$, which was adsorbed at the $MnO_2$ surface. The excessive ozone was decomposed to $O^*$ onto the $MnO_2$ catalyst bed, and then that $O^*$ was reacted with $NO_2$ to form $NO_3^-$. It was found that the optimal $O_3$/NO ratio for catalytic oxidation of NO on $MnO_2$ was 2.0, and the NO removal efficiency on $MnO_2$ was 83% at $30^{\circ}C$. As a result, NO was converted mainly to $NO_3^-$.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.295-310
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• 2013

Industry- or regulatory-sponsored research activities on the resolution of Generic Safety Issue (GSI)-191 were reviewed, especially on the chemical effects. Potential chemical effects on the head loss across the debris-loaded sump strainer under a post-accident condition were experimentally evidenced by small-scale bench tests, integrated chemical effects test (ICET), and vertical loop head loss tests. Three main chemical precipitates were identified by WCAP-16530-NP: calcium phosphate, aluminum oxyhydroxide, and sodium aluminum silicate. The former two precipitates were also identified as major chemical precipitates by the ICETs. The assumption that all released calcium would form precipitates is reasonable. CalSil insulation needs to be minimized especially in a plant using trisodium phosphate buffer. The assumption that all released aluminum would form precipitates appears highly conservative because ICETs and other studies suggest substantial solubility of aluminum at high temperature and inhibition of aluminum corrosion by silicate or phosphate. The industry-proposed chemical surrogates are quite effective in increasing the head loss across the debris-loaded bed and more effective than the prototypical aluminum hydroxide precipitates generated by in-situ aluminum corrosion. There appears to be some unresolved potential issues related to GSI-191 chemical effects as identified in NUREG/CR-6988. The United States Nuclear Regulatory Commission, however, concluded that the implications of these issues are either not generically significant or are appropriately addressed, although several issues associated with downstream in-vessel effects remain.

• 건축역사연구
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• 제28권3호
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• pp.55-66
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• 2019

Pinson Hall is a dormitory building of Chosen Christian College, built in 1922, and it still remains comparatively well preserved as original form. This building is worthy in that it shows the living space of western style college in Korea, as well as characteristics of collegiate gothic style and building technology, designed by western architect in 1920s. At first, based on literate review and field survey, this study aims to trace the construction background and process of Pinson Hall, and find out its architectural characteristics with the original form when it is used as dormitory. Additionally, it deals with historic meaning and value of Pinson Hall as a modern western style college dormitory, through comparison with other dormitories in the same era. In conclusion, Pinson Hall is a Western style dormitory which allows students to accustom themselves to Western life style, using bed and desk, as well as it shows the new building technology in the early 1920s which has mixture of masonry and reinforced concrete structure.

• Structural Engineering and Mechanics
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• 제28권1호
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• pp.1-18
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• 2008

The conventional design of bridge piers against scour uses scour equations which involve number of uncertain flow, sediments and structural parameters. The inherent high uncertainties in these parameters suggest that the reliability of piers must be assessed to ensure desirable safety of bridges against scour. In the present study, a procedure for the reliability assessment of bridge piers, installed in main and flood channels, against scour has been presented. To study the influence of various random variables on piers' reliability sensitivity analysis has been carried out. To incorporate the reliability in the evaluation of safety factor, a simplified relationship between safety factor and reliability index has been proposed. Effects of clear water (flood channel) and live bed scour (main channel) are highlighted on pier reliability. In addition to these, an attempt has also been made to explain the failure of Black mount bridge of New Zealand based on its pier's reliability analysis. Some parametric studies have also been included to obtain the results of practical interest.

• Journal of Welding and Joining
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• 제18권1호
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• pp.91-96
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• 2000

Characteristics of the weld defect, such as a blowhole and a pit in lap-jointed fillet Co₂ welds of Zn-coated steel sheet were studied in order to make clear the sequence of the blowhole formation during welding. Main conclusions obtained are as follows: 1) Blowhole, wormhole and pit were found in fillet welds, although the optimum welding condition of 200A-23V-100cm/min was applied. 2) Zn was only detected at the solidification boundary at the early stage of the blowhole formation. 3) Most of the blowholes was started to form at lap-joint by the Zn vapor. With increasing of the Zn vapor and its pressure, the blowhole was develope to th bed surface until the completion of weld solidification. 4) The behavior of the blowhole in growth was similar to that of the columnar dendrite during welding.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.339-342
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• 2000

황화수소와 암모니아 함유악취의 동시처리를 위해 Thiobacillus sp.IW가 함유된 3상 생물막유동층반응기를 사용하였다. 본 연구에서 황화수소는 미생물에 의해 산으로 전환되었으며 이어서 유입된 암모니아와 반응하여 황산암모늄이 생성됨으로서 양성분은 제거되었다. 황화수소의 경우 45 mg/l h의 유입량에서도 거의 완전한 처리 효율을 보여주었으나, 암모니아의 경우 유입량이 10 mg/l h에서 증가함에 따라 처리효율은 점차 감소하였다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.287-292
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• 1998

The phenomena of local scour due to a current from a seadike closure gap which is protected by rock, then on to an erodible bed, have been studied. Based on the data of hydraulic model test, the scour characteristics have been investigated for the variation of maximum scour depth with time until reaching equilibrium stage and the shape of ultimate scour hole. A brief evaluation of DHL formula for the relationship between maximum scouring depth and time and a dimensionless form leading to time-scale introduced. On the basis of DHL formula, modified DHL formula denoted DHL-RDC formula is extend to the range of estimation of scour depth compared to DHL formula verified by model test.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.400-403
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• 2004

In conventional methods, the availability of floating crane has determined the size of a concrete caisson. However, this paper introduces a new method for larger caisson production that make it possible to complete caisson fabrication and launch out without use of floating crane. The new method carries out multi-step fabrication of caisson and horizontal transfer of caisson on a single casting bed which consists of collapsible soffit form, trough, aero go watercaster system or low frictional PTFE added jacking system, half-submergible floating dock. To make the new method successfully launched, the static and dynamic analysis is carried out to obtain the stability of caisson launching and experimental research is conducted in evaluating friction occurred between PTFE pad and steel track. Lastly, the comparison of the new method and the conventional method are detailed. With significant benefits in construction costs reduction and construction time reduction, this new method in this paper would be recommended for extensive application in large port and harbor construction projects.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.111-114
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• 2008

본 연구에서는 과산화수소 분해 반응을 이용한 초소형 추력기 성능평가를 실시하였다. 물리 화학적 안정성이 뛰어나고 분해 성능이 좋은 백금을 촉매로 사용하고 세라믹 폼을 지지체로 선정하였다. 실험에 사용된 단일 추진제는 90wt% 과산화수소로 질소 가스를 통한 직접 가압 방식으로 추력기에 공급된다. 추력기의 성능을 평가하기 위해서 특성 속도 효율을 구하고 압력곡선을 통해서 압력 상승 시간, 압력 하강 시간, 반응 지연 등을 종합적으로 살펴본다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.512-515
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• 2000

A parallel reactor system which is consisted of two trickle bed reactors (TBR) was developed for the biodegradation of trichloroethylene (TCE) in waste gas stream. The reactor were packed with porous ceramic materials and Burkholderia cepacia G4 was inoculated to form biofilms. Each reactor was operated alternatively in TCE degradation or reactivation mode, and the effect of switching time on TBR performance was investigated. The MO (monooxygenase) activity during the TCE transformation decreased below 10 % within 24 hr, but could be recovered to the initial high level within 10 hr after supplying the reactivation medium supplemented with phenol as a carbon source. This shows that the parallel TBR system has a great potential for the long-term stable treatment of TCE.