• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2578-2590
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• 2023

In this work, a 24-month two-batch fuel management strategy for the APR1400 using LEU + has been investigated, where enrichments of 5.9 and 5.2 w/o are utilized in lieu of the conventional 4-5 w/o UO₂ fuel. In addition, an Accident Tolerant Fuel (ATF) clad based on the swaging technology is applied to APR1400 fuel assemblies. In this special ATF clad design, both outer and inner SS316 layers protect the conventional zircaloy clad. Erbia (Er₂O₃) is introduced as a burnable absorber with two-fold goals to lower the critical boron concentration in the long-cycle LEU + loaded core as well as to handle the LEU + fuel in the existing front-end fuel facilities without renewing the license. Two types of fuel assemblies with different loading of gadolinia (Gd₂O₃) are considered to control both the reactivity and the core radial power distribution. The erbia burnable absorber is uniformly admixed with UO₂ in all fuel pins except for the gadolinia-bearing ones. In this study, two core designs were devised with different erbia loading, and core performance and safety parameters were evaluated for each case in comparison with a core design without any burnable absorbers. The core analysis was done using the two-step method. First, cross-sections are generated by the SERPENT 2 Monte Carlo code, and the 3-D neutronic analysis is performed with an in-house multi-physics nodal code KANT.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 추계학술대회
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• pp.297-302
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• 2004

본 연구에서는 수직배치형 블록을 가지는 컨테이너 터미널을 대상으로 안벽에서 컨테이너의 양${\cdot}$적하 작업을 담당하는 안벽크레인(Q/C)에 대한 하역생산성을 비교분석하였다. 분석 대상이 되는 안벽크레인의 유형은 기존의 싱글트롤리 타입외에 차세대 안벽크레인으로 인식되고 있는 듀얼트롤리, 더블트롤리, 수직순환식의 하역방식을 가지는 장비에 대한 하역생산성을 순작업시간당 생산성 측면에서 이들 하역장비의 성능을 측정해 보았다. 이들 차세대 컨테이너 크레인은 기존의 싱글트롤리 타입의 장비에 비해 기계적 싸이클 타임이 짧으며, 선회방식이 상이하여 현재의 싱글 트롤리타입보다 하역생산성이 매우 높을 것으로 보고 있다. 본 연구의 결과로 제시된 4가지 유형의 안벽크레인에 대해 작업싸이클타임과 시뮬레이션 기법을 이용하여 기계적생산성과 순작업생산성을 산출하였다.

• Steel and Composite Structures
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• 제21권2호
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• pp.343-356
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• 2016

As the common cast-in-place construction works fails to meet the enormous construction demand under rapid economic growth, the development of prefabricated structure instead becomes increasingly promising in China. For the prefabricated structure, its load carrying connection joint play a key role in maintaining the structural integrity. Therefore, a novel end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column was proposed. Under action of low cycle repeated horizontal loadings, comparative tests are conducted on 6 prefabricated pre-stressed intermediate joint specimens and 1 cast-in-place joint specimen to obtain the specimen failure modes, hysteresis curves, skeleton curves, ductility factor, stiffness degradation and energy dissipation capacity and other seismic indicators, and the seismic characteristics of the new-type prefabricated beam-column connecting joint are determined. The test results show that all the specimens for end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column have realized the design objectives of strong column weak beam. The hysteretic curves for specimens are good, indicating desirable ductility and energy dissipation capacity and seismic performances, and the research results provide theoretical basis and technical support for the promotion and application of prefabricated assembly frames in the earthquake zone.

• KEPCO Journal on Electric Power and Energy
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• 제4권1호
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• pp.19-24
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• 2018

가스터빈 동익에 대한 지속적인 국산화 개발이 추진되어, 국내 정밀 주조 기술을 향상시키고, 동익의 유지 보수 비용을 낮추는 등의 직간접적인 긍정적 효과를 가져왔지만, 여전히 국산화 개발품이 발전소에서 안정적인 실사용이 가능한지에 대한 우려가 존재한다. 향상된 소재와 주조기술을 바탕으로 조직학적, 기계적 성질에서 충분한 품질을 확보하였더라도, 개발품을 대상으로 다양한 신뢰성 검증이 요구되는 이유이다. 고속회전시험기는 로터, 디스크 등의 회전체에 원심력을 가하여, 이에 따른 제품의 특성을 분석하기 위한 시험장비로 일반적으로 과속도시험을 통한 최종적인 품질검사에 주로 사용된다. 본 논문에서는 전력연구원에 구축된 고속회전시험기를 활용한 가스터빈 동익에 대한 과속도시험을 포함한 저주기피로시험 사례를 중심으로 신뢰성 시험 및 평가 결과를 기술하였다.

• 콘크리트학회논문집
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• 제15권5호
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• pp.635-642
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• 2003

최근들어 노후화된 교량의 증가에 따라 바닥판의 보강효과에 대한 많은 연구가 이루어지고 있으나 대부분의 연구는 실험실 수준에 국한되어 있으며, 구조물의 피로거동은 이동하중이 아닌 고정반복하중에 의한 연구가 집중적으로 시행되고 있다. 본 연구에서는 이동하중의 영향을 반영하기 위하여 국내에서 실측된 축하중으로 활하중 모델을 제시하였다. 확률론적 해석과 신뢰성 해석을 적용하여 탄소섬유쉬트와 격자형 탄소섬유로 성능향상된 바닥판의 보강효과 및 연장수명을 예측한 결과 성능향상 된 설계 2등급의 교량바닥판은 일반적인 증가 차량하중에 대하여 사용기간동안 충분한 내하력뿐만 아니라 충분한 피로거항성을 갖는 것으로 나타났다.

• 미생물학회지
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• 제30권2호
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• pp.113-118
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• 1992

소양호에서 인(P) 의 순환 과정중 유기인산염 분해율을 1990 1월 부터 1991녕 4 월 까지 측정한 결롸 1-2220 nM/l/hr 의 범위였다. 표층의 경우 8월에 가장 높았으며, 성층이 깨지는 10월과 11 월에는 8월보다 1/240배 이하로 낮은 값이였다. 우기인산염 분해율과 엽록소 a 와는 높은 상관 관계(R = 0.69) 를 나타내었고, specific activity는 겨울에 45-122 nM/hr/$\mu$g chl. a 으로조사기간중 최조값을, 10월에는 2 nM/hr/$\mu$g chl. a 로서 최저값을 나타내었다. 유기인산염 분해율과 DIP 농도와는 역상관의 관계이였다. 성층기에는 식물 플랑크톤이 증식하면서 유도된 alkaline phosphatase 에 의하여 유기인산염을 분해하고, 표, 심층부가 섞이는 가을에는 중, 심츤부로부터 충분한 양의 DIP 가 공급되는 것으로 나타나, 소양호의 부영양화 상태가 매우 심각함을 알 수 있었다.

• Journal of Mechanical Science and Technology
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• 제17권1호
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• pp.1-10
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• 2003

This paper summarizes the results of the fatigue test of four composite bridge decks in extreme temperatures (-30$^{\circ}C$ and 50$^{\circ}C$ ). The work was performed as part of a research program to evaluate and install multiple FRP bridge deck systems in Dayton, Ohio. A two-span continuous concrete deck was also built on three steel girders for the benchmark tests. Simulated wheel loads were applied simultaneously at two points by two servo-controlled hydraulic actuators specially designed and fabricated to perform under extreme temperatures. Each deck was initially subjected to one million wheel load cycles at low temperature and another one million cycles at high temperature. The results presented in this paper correspond to the fatigue response of each deck for four million load cycles at low temperature and another four million cycles at high temperature. Thus, the deck was subjected to a total of ten million cycles. Quasi-static load-deflection and load-strain responses were determined at predetermined fatigue cycle levels. Except for the progressive reduction in stiffness, no significant distress was observed in any of the composite deck prototypes during ten million load cycles. The effects of extreme temperatures and accumulated load cycles on the load-deflection and load-strain response of FRP composite and FRP-concrete hybrid bridge decks are discussed based on the experimental results.

• 대한기계학회논문집
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• 제8권6호
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• pp.569-575
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• 1984

본 연구에서는 가장 하혹한 부식 환경 분위기에서 널리 사용되는 오오스테나 이트계 스테인레스 강재 용접부에 대해 비등 염화 마그네슘 용액 중에서의 SCC 발생 및 전파특성을 초기 응력강도계수(initial Stress intensity factors) $K_{Ii}$ 값에 대하여 비교, 검토함으로서 모재, 용접열 영향부, 용착금속 및 비이드 형상에 따른 용 접부의 SCC 감수성을 정량적으로 구명하였다. 또한 이상과 같은 각 부분의 SCC 특성 을 용접부의 조직적 및 기계적 특성 변화와 관련시켜 고찰하였다.

• 상하수도학회지
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• 제25권6호
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• pp.825-837
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• 2011

Seonakdong river consists of stagnant sections whose flowrate is controlled by the Daejeo and Noksan gates. As a result, there is not a minimum flow during normal times. The Daejeo and Noksan gates are located at the upstream head and the downstream end of Seonakdong river, respectively. Seonakdong river is an estuarine tributary of Nakdong river, which is a reservoir-like river used for agricultural irrigation, with the gate at the estuary of the river to prevent the intrusion of saline. Since the construction of the water gates, the water quality of the river has become degraded. This could also be due to the internal loading of pollutants, especially nutrients, from the sediments of the river because of the elongated detention time by the water gates. This study was thus conducted for the purpose of evaluating the current hydrologic-cycle system and providing measures for the rehabilitation of the hydrologic cycle. In this research, the daily outflow in Seonakdong River was simulated using the SWAT and SWMM models, and the water quality concentration including BOD, SS, TN, and TP were analyzed. The possibility of the application of SWAT-SWMM hybrid simulation was determined through the verification of both models. The error analysis shows that the results of both SWAT and SWAT-SWMM simulations make good agreements with those of field observations. For the single simulation results of SWAT, $R^{2}$ and NSE are 0.758, 0.511, respectively. For the hybrid simulation results of SWAT-SWMM, those are 0.880, 0.452, which means that the hybrid simulation can give more accurate results for the watershed where both the agricultural and urban areas exist.

• Membrane and Water Treatment
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• 제9권3호
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• pp.181-188
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• 2018

A sidestream contains the filtrate or concentrate from the belt filter press, filter backwash and supernatant from sludge digesters. The sidestream flow, which heads back into the sewage treatment train, is about 1-3% less than the influent flow. However, the sidestream can increase the nutrient load since it contains high concentrations of phosphorus and nitrogen. In this study, the removal of PO4-P with organic matter characteristics and bacteriological changes during the sidestream treatment via ladle furnace (LF) slag was investigated. The sidestream used in this study consisted of 11-14% PO4-P and 3.2-3.6% soluble chemical oxygen demand in influent loading rates. LF slag, which had a relatively high $Ca^{2+}$ release compared to other slags, was used to remove $PO_4-P$ from the sidestream. The phosphate removal rates increased as the slag particle size decreased 19.1% (2.0-4.0 mm, 25.2% (1.0-2.0 mm) and 79.9% (0.5-1.0 mm). The removal rates of dissolved organic carbon, soluble chemical oxygen demand, color and aromatic organic matter ($UV_{254}$) were 17.6, 41.7, 90.2 and 77.3%, respectively. Fluorescence excitation-emission matrices and liquid chromatography-organic carbon detection demonstrated that the sidestream treatment via LF slag was effective in the removal of biopolymers. However, the removal of dissolved organic matter was not significant during the treatment. The intact bacterial biomass decreased from $1.64{\times}10^8cells/mL$ to $1.05{\times}10^8cells/mL$. The use of LF slag was effective for the removal of phosphate and the removal efficiency of phosphate was greater than 80% for up to 100 bed volumes.