적니와 석회석을 이용한 혼합 중금속(Cr⁶⁺, Cu²⁺, As³⁺, Pb²⁺)의 제거

강구(Ku Kang),박성직(Seong Jik Park),신우석(Woo Seok Shin),엄병환(Byung Hwan Um),김영기(Young Kee Kim) 大韓環境工學會 2012 대한환경공학회지 Vol.34 No.8

본 연구에서는 적니와 석회석을 이용하여 혼합중금속의 제거능을 평가하였다. 적니의 중금속 흡착은 Pb2+ (94.0%), As³⁺ (67.1%), Cu2+ (37.5%), Cr6+ (36.6%) 순의 흡착률 나타났으며, 석회석은 Pb2+ (30.8%), Cu2+ (16.5%), Cr6+ (11.5%), As³⁺ (8.9%)의 흡착률을 나타내었다. 동적흡착 실험결과를 유사 1차 모델과 유사 2차 모델로 분석한 결과 두 모델 모두 실험결과에 잘 부합하는 것으로 나타났으며 평형흡착 실험결과 Freundlich 모델은 적니와 석회석의 Cr6+, Pb2+ 흡착에 부합하며, Cu2+ 흡착은 Langmuir 모델에 부합하였다. 용액의 pH가 5에서 9로 증가함에 따라서 흡착률은 증가하는 것으로 나타났다. 또한, 적니의 양이 증가함에 따라서 중금속의 흡착률은 증가하였지만, 단위 질량당 흡착량은 조금 감소하였다. 반면, 석회석의 양이 증가하여도 흡착양에 변화가 없는 것으로 나타났다. 본 연구 결과를 통해 적니와 석회석은 중금속을 효율적으로 제거할 수 있는 흡착제로 판단된다. This study examined the removal rate of heavy metals from synthetic control water using red mud and lime stone. Overall, the percent of absorption obtained in this study for the red mud treatment was 94.0% (Pb2+), 67.1% (As³⁺), 37.5% (Cu2+), and 36.6% (Cr6+), while that of lime stone was Pb2+ (30.8%), Cu2+ (16.5%), Cr6+ (11.5%), and As³⁺ (8.9%). The kinetic data presented that the slow course of adsorption follows the Pseudo first and second order models, the equilibriuim adsorption of Cr6+ and Pb2+ obeys Freundlich isotherm model, while the adsorption of Cu2+ obeys only Langmuir model. The results also showed that adsorption rate slightly increased with increasing pH from 5 to 9. Interestingly, this trend is similar to results obtained as function of loading amount of red mud. Meanwhile, an unit adsorption rate was slightly decreased. For lime stone, it did not much change in adsorption as function of treatment amount. Consequently, it was concluded that the absorbents can be successfully used the removal of the heavy metals from the aqueous solutions.

마이너스 자화 스피넬 산화물의 연 X선 방사광 분광 연구

양민영(Min Young Yang),성승호(Seungho Seong),이은숙(Eunsook Lee),강정수(J.-S. Kang) 한국자기학회 2020 韓國磁氣學會誌 Vol.30 No.2

By employing soft X-ray absorption spectroscopy (XAS) and soft X-ray magnetic circular dichroism (XMCD), the electronic structures of Li<SUB>0.5</SUB>FeCr<SUB>1.5</SUB>O₄ spinel ferrite have been investigated, which exhibits the negative magnetization phenomenon. It is found that that both Fe and Cr ions are trivalent, that most of Fe3+ ions occupy the A (T<SUB>d</SUB>) sites while Cr<SUP>3+</SUP> ions occupy the B (O<SUB>h</SUB>) sites, and that the magnetic moments of Fe ions and those of Cr ions are coupled antiferromagnetically to each other. Hence Li<SUB>0.5</SUB>FeCr<SUB>1.5</SUB>O₄ can be represented as (Fe)<SUB>A</SUB>[Li<SUB>0.5</SUB>Cr<SUB>1.5</SUB>]<SUB>B</SUB>O₄.

화강풍화토와 무기질 결합재를 활용한 친환경 흙포장에 관한 연구

정혁상(Jung Hyuksang),장철호(Jang Cheolho),안병제(An Byungjae),천병식(Chun Byungsik) 한국지반환경공학회 2009 한국지반환경공학회논문집 Vol.10 No.4

본 연구의 목적은 기존 흙 포장의 문제점인 장기적인 내구성 결여 및 균열발생을 보완한 친환경적 흙포장재를 개발하기 위한 것이다. 액상형태의 혼합이 용이한 무기질 결합재와 화강풍화토를 첨가량별로 배합하여 일축압축시험 및 투수시험을 실시하였다. 시험결과에 따라 적정 배합비를 산정하고 6가크롬(Cr<SUP>6+</SUP>)검출시험, 재령별 SEM촬영, 동결융해시험을 실시하여 적정성을 검증하였다. 연구 결과, 분말형 무기계 결합재의 배합비는 시멘트:플라이애시:석고의 비율이 각각 50:33:7이 가장 적합한 것으로 판단되었다. 그리고 6가크롬(Cr<SUP>6+</SUP>) 검출시험결과 6가크롬(Cr<SUP>6+</SUP>)의 발생량이 미미하였고, SEM촬영 결과 재령 3일에 에트린자이트 형성이 확인되어 재료가 화학적으로 조기강도 발현이 가능함을 알 수 있었다. In this study, the problem of existing soil pavement is a long-term durability lack and crack occurrence. It complements in order to develop the environmental soil pavement material which composites readily blended mineral binder of liquid and decomposed granite soils. It was estimated optimal mixture proportion for unconfined compressive strength, permeability, CR<SUP>6+</SUP> detection test, SEM test with age, freezing and thawing test. It resulted mixture proportion of powder types mineral binder for rates of cement : fly ash : plaster was optimal rates of 50 : 33 : 7, and CR<SUP>6+</SUP> detection test as a result was a slight production. SEM test with 3days as a result was made Ettringite. It was found that this material was early development of early-strength for chemical. This study indicated that it will execute field appliciability Evaluation test, examination of soil pavement method with decomposed granite soils and mineral binder.

시멘트 고화제 고결공법에서 발생하는 Cr⁶⁺의 환경영향 검토

오영민,김경태 한국해안해양공학회 2002 한국해안해양공학회 논문집 Vol.14 No.4

항만공사 시에 연약지반을 개량하기 위한 방법에는 여러 가지가 있는데 그 중에서 최근에 시멘트 고화제를 주입하는 방법이 많이 이용되고 있다. 그러나 이 방법은 시멘트 고화제에 함유된 6가 크롬(Cr⁶⁺)이 해수 중에 용출되어 수질환경을 악화시킬 수 있다는 논란이 일고 있다. 이러한 논란을 확인하기 위하여 현재 이 방법을 이용하여 연약지반 개량공사를 수행하고 있는 천수만의 오천항에서 현장관측을 실시하였다. 자료 분석결과, 용출수에서는 환경기준을 초과하는 Cr<sub>6+</sup>이 발견되지 않았다. Recently, the injection of cement stabilizer is used as one of ways to improve soft sea-bottom. However, this method makes an argument with Cr⁶⁺subject to emerge to the seawater from the cement stabilizer. To investigate the amount ofCr⁶⁺field measurements were carried out in Ochun harbor of Chunsoo Bay. The analysis shows the amount of Cr⁶⁺in the seawater met the demand of environmental criterion.

아파트 오수정화시설의 처리현황과 주변인자에 대한 연구

선용호(Yong-Ho Seon) 상지대학교 환경과학기술연구소 1999 환경과학연구 Vol.5 No.1

  본 연구는 생활하수 배출시설 중 인구밀집시설인 원주 단계 택지내 아파트를 임의로 3곳을 지정하여 아파트 오수정화시설의 처리효율을 알아보고, 전년도 처리효율과의 비교를 통하여 주변인자에 의한 영향에 대해 알아보고자 하였다. 실험은 Standard Method와 수질오염공정시험법에 준하여 10개항목을 실시하였다. 실험결과를 보면 전년에 비하여 BOD, COD<SUB>Cr</SUB> 제거율이 약 10~13%정도 낮아졌으며, 이는 IMF이후 경제적인 요인으로 인해 아파트 관리소 측의 폐슬러지 수거나, 오수정화시설의 정비 불량 등 관리 소홀과 각 가정의 식생활 패턴이 경제적인 식단으로 바뀌어가기 때문인 것으로 판단된다. 전년과 마찬가지로 각 아파트 오수정화시설은 방류수 수질기준에 크게 미치지 못하는 수치를 나타냈으며, 이에 대한 해결 방안으로 오수정화시설의 전문환경관리인에 의한 관리와 계절적인 요인이나, 입주자들의 식생활 패턴 등 주변인자에 대한 철저한 분석과 대응이 필요할 것으로 사료된다.   It was carried out a performance test for sewage treatment systems in three highly populated apartments located in dangae building site in Wonju, and comparing the last year"s results investigated the environmental effects about the study site on the performance. EPA Standard Method and Korea Standard Method were used for analyses of 10 items in our experiments. Because of the weak maintenance of sewage treatment systems with the change of life style due to the change of economic menu pattern after IMF, it was found that the removal efficiency of BOD and COD<SUB>Cr</SUB> was decreased in 10~13%. As same as last year"s results, it was found that the effluent concentration of BOD and SS was higher than the standard limits. We suggest that the solution of above problems is the improvement of the management of environmental engineer and the analysis of the envionmental effects.

재활시스템 구동을 위한 수소저장합금의 제조 특성 분석

신미연,권대규,유창호 제어로봇시스템학회 2019 제어로봇시스템학회 각 지부별 자료집 Vol.2019 No.1

In this paper, Zr0.9Ti0.1Cr0.6Fe1.4 and Zr0.9Ti0.1Cr0.7Fe1.3 were selected as Metal-Hydride(MH) alloys for driving the rehabilitative system. The MH alloys were fabricated by Arc-melting and the compositions of its were analyzed by Field Emission Scaning Electron Microscope(FE-SEM), Energy Dispersive X-ray Spectroscopy(EDS), X-Ray Diffractometry(XRD) and Inductively Coupled Plasma(ICP). As a result of the analysis, the alloys were nonuniform in composition although it was prepared as a single phase of hexagonal structure. In the future, the hydrogen storage capacity of the MH alloys will be evaluated by producing P-C-T diagram of each MH alloys. And MH alloys will be used at driving actuation system for confirming its actual performance.

고온피로균열성장 수명평가 모델 개선을 위한 크리프-역전 변수 도입

마영화(Young-Wha Ma),백운봉(Un-Bong Baek),윤기봉(Kee-Bong Yoon) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.8

Crack growth at elevated temperatures becomes an important consideration in estimating the remaining life, in determining the operating conditions and in deciding the inspection criterion and intervals. Fracture mechanics approaches that have been developed over the past few decades have proven useful in providing a rigorous framework for accomplishing these goals. In this paper, for improvement of creep-fatigue crack growth behavior model, it was performed to study for creep-reversal parameter measurement. Because conventional models to evaluate values of (Ct)avg become unuseful for creep-ductile materials with expensive ranges of the effect of cyclic plasticity for creep deformation. creep-fatigue crack growth tests for CR(creep-reversal parameter) measurements were tested by using trapezoidal loading waveforms with hold times of 0, 60, 600 and 3600 seconds. Measurements of the load-line deflection change and degree of reversal during hold periods were made using an elevated temperature clip-on capacitance gage. These reversed deflection changes were then used to calculate the experimental values of CR without any assumptions with regards to the creep deformation behavior of the materials or effects of cyclic plasticity. thus, The experimentally defined creep-reversal parameter, CR, will provide a direct means to accurate calculating (Ct)avg.

재생냉각 연소기의 냉각기구에 따른 냉각 특성 파악

김홍집(Hong Jip Kim),최환석(Hwan-Seok Choi) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.5

연료링의 위치 및 열차폐 코팅의 종류에 따른 연소기의 재생냉각 특성을 검토하였다. 연료링을 노즐의 중간 부분에 위치시키고 냉각채널을 분기시켜서 설계하는 방법이 열적으로 타당함을 확인하였다. 또한 복합재를 이용한 노즐확장부가 적용 가능한 기술적 상황이라면, 팽창비가 높고 열유속이 낮은 노즐 후류 부분은 이를 이용하는 것이 매우 적절하다고 판단된다. 적용 가능한 열차폐 코팅 중에서 30톤급 연소기 및 가스발생기 개발과정에서 사용했던 Y2O3 stabilized ZrO2과 내산화성이 우수한 Ni/Cr을 고려하였다. 내산화성이 우수한 Ni/Cr에 비해 세라믹 코팅(Y2O3 stabilized ZrO2)이 열차폐 효과가 우수한 것으로 파악되었다. Thermal analyses have been performed to study the effect of location of fuel ring and thermal barrier coatings in regenerative cooling channels in a full-scale combustor. For the effective cooling, the fuel ring has better be installed near axial location of the low expansion ratio and low heat flux, and branching of cooling channels is preferable. Also, the radiative cooled nozzle extension is thought to be reasonable for the cooling of combustion walls. Among the possible coatings, Y2O3 stabilized ZrO2 coating and Ni/Cr coating have been adopted. Compared with Ni/Cr coating which has high oxidation resistance, Y2O3 stabilized ZrO2 coating, one of ceramic coatings is found to be much effective to sustain the thermal survivability of combustion walls.

Fe-Si-Cr 분말합금의 열처리 효과

장평우(Pyungwoo Jang) 한국자기학회 2016 韓國磁氣學會誌 Vol.26 No.1

Effects of annealing of the gas-atomized Fe-9%Si-2%Cr powder which is suitable for high frequency application in mobile devices because of its high electrical resistivity were studied with an emphasis on the order-disorder phase transition. The formation of B2 ordered phase could not be suppressed during atomization process. When the powder was annealed at a temperature higher than 550 ℃ the peak diffracted from DO<SUB>3</SUB> phase could be detected. With increasing annealing temperature lattice parameter and coercivity decreased. An interesting phenomenon was an abrupt increment of coercivity in the powder annealed at 450 ℃. Highest permeability could be shown in the powder annealed at a relative low temperature of 150 ℃ and then the permeability decreased with annealing temperature. The above-mentioned results could be successfully explained by both the formation of DO<SUB>3</SUB> ordered phases and the change of electrical resistivity of the Fe-Si-Cr powder which was also originated from the phase transition.

Comparison of Creep Crack Growth Rates on the Base and Welded Metals of Modified 9Cr-1Mo Steel

Woo-Gon Kim(김우곤),Jae-Young Park(박재영),Song-Nan Yin(윤송남),Sung-Ho Kim(김성호),Yong-Wan Kim(김용완),Seon-Jin Kim(김선진) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

This paper is to compare creep crack growth rates (CCGR) on the base metal (BM) and welded metal (WM) of modified 9Cr-1Mo steel for Gen-IV reactors. Welded specimens were prepared by Shielded Metal Arc Weld (SMAW) method. To obtain material properties for the BM and welded metal, a series of creep and tensile tests was conducted at 600℃, and CCG tests was also performed using 1/2 compact tension specimens under different applied loads at 600℃. Their CCGR behaviors were analyzed by using the empirical equation of the da/dt vs. C<SUP>*</SUP> parameter and compared, respectively. It appeared that, for a given value of C<SUP>*</SUP>, the rate of creep propagation was about 2.0 times faster than in the WM than the BM. This reason is that a creep rate in the WM was largely attributed when compared with that in the BM. From this result, it can be utilized for assessing the rate of creep propagation on the BM and WM of the G91 steel.