• 한국건설순환자원학회논문집
• /
• 제2권3호
• /
• pp.180-187
• /
• 2014

본 연구에서는 시멘트 사용량을 저감하고 다량의 혼화재를 사용하여 고강도 콘크리트 제조 과정에서 시멘트에 의한 $CO_2$ 발생량을 감소시킬 목적으로 혼화재 및 무기계 자극제를 사용한 고강도 콘크리트의 역학적 특성을 평가하였으며, HVMA 결합재 도출과 W/B 변화 및 양생온도에 따른 HVMA 고강도 콘크리트를 실험하였다. 실험결과, 다량의 혼화재와 무기계 자극제인 열병합애시와 무수석고를 혼합 사용한 HVMA 결합재 배합을 설계하였으며, 설계된 HVMA 결합재를 사용할 경우 W/B 26% 수준에서 HVMA 고강도 콘크리트 배합이 유동특성과 역학적 특성이 양호한 것으로 나타났다. 또한 HVMA 결합재를 사용한 고강도 콘크리트의 양생온도 영향을 검토한 결과, 양생온도 $20^{\circ}C$ 이상 확보한 경우에는 50MPa 이상의 고강도 HVMA 고강도 콘크리트 제조가 실용화 가능성이 높은 것으로 나타났다.

• 화약ㆍ발파
• /
• 제8권1호
• /
• pp.3-16
• /
• 1990

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill $\varphi{70mm}$ on the calcalious sand stone(sort-moderate-semi hard Rock). The total numbers of feet blast were 88. Scale distance were induces 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites (m) W : Maximum Charge per delay-period of eighit milliseconds or more(Kg) K : Ground transmission constant, empirically determind on th Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity $D/W^b$ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three graups. Cabic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge per delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m----under l00m----- $V=41(D/3\sqrt{W})^{-1.41}$ -----A Over l00m-----$V= 121(D/3\sqrt{W})^{-1.66}$-----B K value on the above equation has to be more specified for furthur understang about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• 화약ㆍ발파
• /
• 제9권4호
• /
• pp.3-12
• /
• 1991

The cautious blasting works had been used with emulsion explosion electric M /S delay caps. Drill depth was from 3m to 6m with Crawler Drill 70mm on the calcalious sand stone (soft-moderate-semi hard Rock) . The total numbers of feet blast were 88. Scale distance were induces 15.52-60.32. It was applied to Propagation Law in blasting vibration as follows .Propagtion Law in Blasting Vibration V=k(D/W/sup b/)/sup n/ where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W ; Maximum Charge per delay -period of eight milliseconds or more(Kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity D/W/sup b/ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three groups. Cabic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over loom distance because the frequency is varified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m--under 100m----V=41(D/ W)/sup -1.41/-----A Over l00m---------V=121(D/ W)/sup -1.56/-----B K value on the above equation has to be more specified for furthur understand about the effect of explosives. Rock strength, And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• 자원리싸이클링
• /
• 제31권3호
• /
• pp.40-52
• /
• 2022

탄소광물화 기술은 석탄재와 이산화탄소를 반응시켜 건설재료 등으로 활용이 가능한 복합탄산염 등의 부산물을 생산함과 동시에 이산화탄소를 탄산염에 고정화하여 온실가스 감축효과를 얻을 수 있는 기술로, 이산화탄소 감축 및 경제적 잠재력을 고려하면 국가 온실가스 감축 목표를 실현하기 위한 유용한 방안이 될 수 있다. 그러나 아직까지는 해당 기술의 이산화탄소 감축 성능과 환경적인 이점, 경제성 등에 대한 자료가 적어서 기술의 상용화 가능성에 대해서는 명확하지 않은 상태이다. 본 연구는 국내 순환유동층 발전소에서 발생되는 이산화탄소와 석탄재를 이용하는 이산화탄소 투입량 기준 6,000 tonCO₂/년 규모의 탄소광물화 설비에 대해 이산화탄소 감축량 및 경제성 분석을 수행했다. 공정 분석 결과 1톤의 복합탄산염 생산 시 실질적인 이산화탄소 감축량은 약 45.8 kgCO₂eq, 연간 약 805.3 tonCO₂로 산정되었으며, 경제적 편익 분석 시 비용편익분석비(B/C Ratio)는 1.04, 내부수익률(IRR)은 10.65 %, 순현재가치(NPV)는 24,713,465 원으로 나타나, 탄소광물화 설비가 어느 정도 경제성을 확보하고 있는 것으로 분석되었다.

• 한국유기농업학회지
• /
• 제32권1호
• /
• pp.91-105
• /
• 2024

본 연구에서는 페놀 화합물, 라디칼 소거능, 환원능력 분석 및 세포 내 ROS 측정을 통해 질경이 추출물의 항산화 능력을 확인하였다. 질경이 추출물의 총 폴리페놀 및 플라보노이드함량은 각각 50.91±0.78 mg GAE/g, 100.99±0.44 mg rutin/g으로 나타났으며, DPPH 및 ABTS radical 소거능과 환원력 모두 농도 의존적으로 증가하였다. 또한, 세포 내 ROS는 질경이 추출물에 의해 생성이 억제됨을 확인하였다. 항염증 활성은 RAW 264.7 세포를 이용하여 염증을 유도한 뒤 NO 측정과 western blot 분석을 통해 염증성 단백질 발현량을 확인하였다. 질경이 추출물은 LPS를 처리한 RAW 264.7 세포에서 NF-ĸB의 신호 전달 경로를 억제하여 염증성 단백질인 iNOS 및 COX-2의 발현량을 조절하였으며, 이로 인해 NO의 생성량을 억제하였다. 본 실험 결과를 통해 질경이 추출물의 항산화 및 항염증에 대한 우수한 활성을 확인하였으며, 식의약품 분야를 비롯한 농산업 분야에서 다양한 기능성 천연 소재로 활용될 수 있을 것으로 기대된다.

• Nuclear Engineering and Technology
• /
• 제45권5호
• /
• pp.637-652
• /
• 2013

Instrumentation and control systems in nuclear power plants have been digitalized for the purpose of maintenance and precise operation. This digitalization, however, brings out issues related to cyber security. In the most recent past, international standard organizations, regulatory institutes, and research institutes have performed a number of studies addressing these systems cyber security.. In order to provide information helpful to the system designers in their application of cyber security for the systems, this paper presents methods and considerations to define attack vectors in a target system, to review and select the requirements in the Regulatory Guide 5.71, and to integrate the results to identify applicable technical security control requirements. In this study, attack vectors are analyzed through the vulnerability analyses and penetration tests with a simplified safety system, and the elements of critical digital assets acting as attack vectors are identified. Among the security control requirements listed in Appendices B and C to Regulatory Guide 5.71, those that should be implemented into the systems are selected and classified in groups of technical security control requirements using the results of the attack vector analysis. For the attack vector elements of critical digital assets, all the technical security control requirements are evaluated to determine whether they are applicable and effective, and considerations in this evaluation are also discussed. The technical security control requirements in three important categories of access control, monitoring and logging, and encryption are derived and grouped according to the elements of attack vectors as results for the sample safety system.

• Corrosion Science and Technology
• /
• 제17권6호
• /
• pp.279-286
• /
• 2018

Austenitic stainless steels used in nuclear power plants mainly use pipes made of seamless pipes, which depend on imports. The manufacturing process and high cost are some of the problems associated with seamless pipes. Therefore, in this study, the corrosion characteristics of the seamless pipe and the SAW pipe were assessed to determine the safety and reliability of the SAW pipe in a bid to replace the seamless pipe. Microstructure was analyzed using an optical microscope and the degree of hardness was measured using a Rockwell B scale. Intergranular corrosion resistance was evaluated by ASTM A262 Practice A, C, and E methods. The degree of sensitization was determined using a DL-EPR test. Anodic polarization test was performed in deaerated 1% NaCl solution at $30^{\circ}C$ and the U-bend method was used to evaluate the SCC resistance in 0.01 M $Na_2S_4O_6$ at $340^{\circ}C$ and 40% NaOH solution at $290^{\circ}C$. Weld metal of the SAW pipe specimen showed relatively high degree of sensitization and intergranular corrosion rate. However, annealing to SAW pipes improved the corrosion properties in comparison to that of the seamless pipe.

• Nuclear Engineering and Technology
• /
• 제53권5호
• /
• pp.1676-1685
• /
• 2021

We develop a new high-fidelity multiphysics model to simulate boron chemistry in the porous Chalk River Unidentified Deposit (CRUD) deposits. Heat transfer, capillary flow, solute transport, and chemical reactions are fully coupled. The evaporation of coolant in the deposits is included in governing equations modified by the volume-averaged assumption of wick boiling. The axial offset anomaly (AOA) of the Seabrook nuclear power plant is simulated. The new model reasonably predicts the distributions of temperature, pressure, velocity, volumetric boiling heat density, and chemical concentrations. In the thicker CRUD regions, 60% of the total heat is removed by evaporative heat transfer, causing boron species accumulation. The new model successfully shows the quantitative effect of coolant evaporation on the local distributions of boron. The total amount of boron in the CRUD layer increases by a factor of 1.21 when an evaporation-driven increase of soluble and precipitated boron concentrations is reflected. In addition, the concentrations of B(OH)₃ and LiBO₂ are estimated according to various conditions such as different CRUD thickness and porosity. At the end of the cycle in the AOA case, the total mass of boron incorporated in CRUD deposits of a reference single fuel rod is estimated to be about 0.5 mg.

• 대한기계학회논문집B
• /
• 제39권4호
• /
• pp.317-324
• /
• 2015

본 연구에서는 아파트단지에 적용되는 태양열 급탕 시스템의 에너지 활용도를 높이기 위해 유기랭킨사이클을 적용하여 해석적 연구를 수행하였다. 시스템 해석은 Aspen $Plus^{(R)}$을 활용하였으며 태양열집열기는 급탕 온도와 유기랭킨 사이클의 운전 조건을 고려하여 진공관형 집열기를 적용하였다. R134a, R141a, R245fa 등의 냉매를 작동유체로 선정하였으며, 시스템 성능해석을 통하여 R245fa 냉매가 적용가능성이 가장 높게 나타났다. 비가역성 해석과 민감도 해석을 통해 유기랭킨 사이클 시스템의 효율 및 성능 확보를 위해서는 증발기와 터빈에 대한 기술 개발이 매우 중요하다는 것을 밝혀냈으며, 순수 급탕으로만 활용하는 시스템에 전기 생산 설비를 추가하게 되면 약 50%의 추가적인 경제성이 확보됨을 확인하였다.

• Nuclear Engineering and Technology
• /
• 제52권6호
• /
• pp.1164-1171
• /
• 2020

T-junction structures play an important role in nuclear power plant systems. Research on liquid entrainment is mostly based on small-scale branch pipes (d/D ≤ 0.2) and attention paid to large-scale branch pipes (0.33 < d/D < 1) is insufficient. Accordingly, this study implements a series of experiments on the liquid entrainment of T-junction with different angles (32.2°,47.9°,62.3°,90°) through a large-scale branch (d/D = 0.675). The onset liquid entrainment is related to the gas phase Froude number Fr_g, the dimensionless gas chamber height h_b/d and the branch pipe angle 𝜃. As Fr_g increases, h_b/d also rises. With a constant h_b/d, the onset liquid entrainment changes from droplets entrainment by the gas phase to that by the rising liquid film. The steady-state liquid entrainment is related to w_3g, h/d and 𝜃. With constant w_3g and h/d, the branch quality grows as the branch angle increases. With a certain h/d, the branch quality increases, as the w_3g number increases.