• International Journal of Advanced Culture Technology
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• 제10권2호
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• pp.220-224
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• 2022

The efficiencies of rates and energy in the fifth generation (5G) wireless channels can be improved via intelligent reflecting surface (IRS) transmissions, towards the sixth generation (6G) mobile communications. While previous works have considered mainly optimizations of IRS transmissions, we propose a performance analysis on the total power in terms of the number of reflecting devices for IRS transmissions in non-orthogonal multiple access (NOMA) networks. First, we derive an analytical expression of the total power gain factor in terms of the number of reflecting devices for the cell-edge user in IRS-NOMA systems. Then we evaluate how many reflecting devices we need to obtain a total power gain in dB. Moreover, we also demonstrate numerically the signal-to-noise ratio (SNR) gain of the IRS-NOMA system over the conventional NOMA system based on the achievable data rate.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1471-1480
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• 2020

This research presents a case study on the remediation of a radioactive waste (uranium: U) utilizing a multi-objective fuzzy optimization in an electrocoagulation process for the iron-stainless steel and aluminum-stainless steel anode/cathode systems. The incorporation of the cumulative uncertainty of result, operational cost and energy consumption are essential key elements in determining the feasibility of the developed model equations in satisfying specific maximum contaminant level (MCL) required by stringent environmental regulations worldwide. Pareto-optimal solutions showed that the iron system (0 ㎍/L U: 492 USD/g-U) outperformed the aluminum system (96 ㎍/L U: 747 USD/g-U) in terms of the retained uranium concentration and energy consumption. Thus, the iron system was further carried out in a multi-objective analysis due to its feasibility in satisfying various uranium standard regulatory limits. Based on the 30 ㎍/L MCL, the decision-making process via fuzzy logic showed an overall satisfaction of 6.1% at a treatment time and current density of 101.6 min and 59.9 mA/㎠, respectively. The fuzzy optimal solution reveals the following: uranium concentration - 5 ㎍/L, cumulative uncertainty - 25 ㎍/L, energy consumption - 461.7 kWh/g-U and operational cost based on electricity cost in the United States - 60.0 USD/g-U, South Korea - 55.4 USD/g-U and Finland - 78.5 USD/g-U.

• International Journal of Aerospace System Engineering
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• 제4권2호
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• pp.5-9
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• 2017

In a pressurized fuel supply system of aircraft, a flow passage opening device is required to keep fuel continuously transferred from one tank to the other. The device utilizes balancing weights in order to follow up an acceleration at special conditions such as negative g. It is very difficult to test the device in a real high-speed and high-altitude test since severe test conditions and expensive supports are needed. Therefore, this paper deals with performance analysis of a flow passage opening device through low speed aircraft captive flight tests (CFT) including roll and negative-g maneuvers. It is shown that balancing weights in the device can open the passage in accordance with fuel position.

• 한국농공학회지
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• 제39권5호
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• pp.97-108
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• 1997

Natural wastewater treatment systems using the constructed wetland system were evaluated for the wastewater from the industrial complex in rural areas. For the treatment of wastewater from the industrial complex in rural area, a pilot plant of the constructed wetland system was installed at Baeksuk agri-industrial complex in ChunahnCity, Chunchungnam-Do. The experiment with this pilot plants was performed for 1996 and 1997. Results of the study were summarized as follows. For the BOD and COD, when the pollutant loading of them was about 1 3.8g/$m^2$. day (the concentration was l24.0mg/${\ell}$) arid 24.4g/$m^2$.day(the concentration was 220.Omg/${\ell}$), the removal rate of them was high, 90.2% and 93.4%, respectively. For the SS, the effluent concentration was consistently lower than the water quality standard even though the influent concentration varied significantly, which showed that SS was removed by the system effectively which consist of soil and plants. For the T-N and T-P, when the influent pollutant loading of them were moderately high, 2.8g/$m^2$.day to 7.4g/$m^2$. day(concentration 25.0mg/${\ell}$ to 49.7mg/${\ell}$) for T-N and 1.0g/$m^2$.day to 2.6g /$m^2$.day(concentration 8.6mg/${\ell}$ to 14.7mg/${\ell}$) for T-P, the removal rate of them were 86.5% and 94.0%, respectively. The removal rate by the flow distance increased rapidly in the first 4m from the inlet zone, and gradually there after. The width of system was 2m. Overall, the result showed that constructed wetland system is a feasible alternative for the treatment of wastewater from industrial complex in rural areas. Compared to existing systems, this system is quite competitive because it requires low capital cost, almost no energy and maintenance, and therefore, very cost effective.

• 한국환경성돌연변이발암원학회지
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• 제8권1호
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• pp.13-21
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• 1988

Mutagenic actions of aflatoxin B$_1$ (AFB$_1$) in the presence of various concentrations of L-ascorbIc acid (AA) in Salmonella typhimurium strains TA 100 and TA98 were studied. Spontaneous revertants per plate of the tester strains TA100 and TA98 were 121-125 and 25-30 with or without S9 mix, respectively. The negative controls used in the study did not show any mutagenesis in the tester strains. AFB$_1$ revealed strong mutagenicity at the dose levels of 0.05, 0.1 and 0.25 ${\mu}$g/plate with metabolic activation system in both strains. However, it showed a toxic effect when the levels were more than 0.5 ${\mu}$g/plate. When lower concentrations of AA (5-20 ${\mu}$g/plate) were added to AFB$_1$ in the Ames assay system with S9 mix the mutagenic action of AFB$_1$ decreased in both strains. About 70-90% of mutagenicity of AFB$_1$ disappeared in strain TA100 when 20${\mu}$g of AA was added to 0.05 ${\mu}$g of AFB$_1$. The inhibitory effect was greatly increased by the addition of higher concentrations of AA to AFB$_1$ in TA100 strain. The mutagenicity of AFB$_1$ was completely inhibited when 100 ${\mu}$g and 500 ${\mu}$g of AA were added to 0.05 ${\mu}$g and 0.1 ${\mu}$g of AFB$_1$, respectively, However, this protective effect of AA on AFB$_1$ mediated mutagenesis was less effective in TA98 strain than that in TA100.

• 한국컴퓨터정보학회논문지
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• 제27권9호
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• pp.113-120
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• 2022

본 논문에서는 5G 네트워크에서 Null 보안 알고리즘 (Null Security Algorithm)을 악용한 IP 스푸핑 공격 (IP Spoofing Attack)의 실현 가능성을 3GPP 표준 규격에 근거하여 분석한다. 3GPP 표준 규격에 따르면, 초기 Registration Request 메시지는 암호화 및 무결성 보호를 받지 못한다. IP 스푸핑 공격은 피해자 UE (User Equipment)의 초기 Registration Request 메시지의 내용을 악의적인 gNB (next generation Node B)가 수정한 뒤 AMF (Access and Mobility Management Function)에게 전송할 수 있다는 취약점을 활용하는 공격이다. 공격이 성공하면, 피해자 UE는 5G 네트워크에서 연결이 끊어지고 악의적인 UE가 인터넷 서비스를 사용하지만 5G 사업자는 피해자 UE에게 요금을 청구한다. 본 논문에서는 IP 스푸핑 공격을 구성하는 각각의 시그널링 메시지가 3GPP Rel-17 표준 규격에서 허용되는 것인지 여부를 분석함으로써 IP 스푸핑 공격의 실현 가능성을 분석한다. 분석 결과, 3GPP Rel-17 표준 규격에 따라 구현된 5G 시스템에서 IP 스푸핑 공격은 실현 불가능한 공격으로 판단된다.

• 농약과학회지
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• 제3권1호
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• pp.57-65
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• 1999

세계적으로 환경생태독성의 주요지표종으로 저니토독성시험에 주로 이용되는 깔따구(Chironomus riparius)를 이용하여 물만으로한 시험계와 물과 토양이 공존하는 시험계 사이의 $^{14}C$-lambda-cyhalothrin의 생물학적인 독성과 농약잔류양상의 차이를 비교하였다. 물과 토양이 공존하는 시험계에서는 물중 lambda-cyhalothrin 잔류량이 약제처리후 5일에서 처음 처리 농도의 99%이상이 감소하는 것으로 나타났으나 물만을 처리한 시험계에서는 처음농도의 약 35%가 감소하였다. Lambda-cyhalothrin의 Chironomus riparius에 대한 독성시험에서 물만 있는 용기에서와 물과 토양이 공존하는 시험계에서의 72시간 $LC_{50}$이 각각 $0.156{\mu}g/{\ell}$이하와 889 ${\mu}g/kg$으로 물과 토양이 공존하는 용기에서의 독성이 약 5,000배 이상 낮은 것으로 나타났다. 따라서 토양과 물 사이의 흡착분배계수의 차이에 의해 물 중 lambda-cyhalothrin의 잔류량이 감소하고 이에 따라 시험생물에 대한 독성도 감소함을 알 수 있었다.

• KSBB Journal
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• 제8권5호
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• pp.478-482
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• 1993

LSM을 이용하여 KA112 균주의 고농도 배양을 시도하였다. Separator로는 hollow fiber를 사용하였고 reactor로는 Celligen을 이용하였다. Wroking volume 1리터로 10일간 배양하여 최고 세포농도가 회분식 배양에 비하여 10배 이상 증가한 $2.1\times10^7$ cells/ml이었고, 항체의 농도는 4.5배 정도 높았다. 최고 feed rate에서 항체생산속도는 회분식 배양보 다 9배 높았으며 배양 중 glucose농도가 Ig/e 이상일 때 specific productivity가 증가하였고, 1 g/6 이하얼 때 세포성장은 영향을 받지 않으냐 spe­c cific prodictivity는 감소하였다.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.363-369
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• 2011

Total ammonia nitrogen (TAN) removal efficiencies of a sand filter (SF), polystyrene microbead filter (PF), and Kaldnes bead filter (KF) media were evaluated under ammonia loading rates of 5, 25, and 50 g $m^{-3}day^{-1}$. The volume of each filter media tested was 7 L, and the water flow rate for all filter media was 24 L/min. The specific surface areas of the SF, PF, and KF were 7,836, 3,287, and 500 $m^2/m^3$, respectively. Sand was fluidized and the other two media were trickle filtered. The volumetric TAN removal rate increased with increasing ammonia loading rate for all filter media. Mean volumetric TAN removal rates under the ammonia loading rates of 5, 25, and 50 g $m^{-3}day^{-1}$ in SF (39.3, 168.6, and 322.7 g $m^{-3}day^{-1}$, respectively) were higher than those in PF (35.0, 157.4, and 310.5 g $m^{-3}day^{-1}$, respectively) and KF (32.1, 142.5, and 288.1 g $m^{-3}day^{-1}$, respectively). These results were related to differences in the specific surface areas of the filter media. PF was the most economic media for efficiently removing TAN.

• 생물환경조절학회지
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• 제1권2호
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• pp.169-174
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• 1992

간격침적식 수경재배의 실용화 가능성을 검사하고자 10분간격 간격침적식, 15분간격 간격침적식, NFT식 및 분무경system을 이용하여 토마토에 대한 생육비교 실험을 수행하였다. 1. 초장은 NFT식에서 가장 양호하였으나 주근장은 간헐침지식에서 길었으며 수경과 엽수는 처리간에 차이가 없었다. 2. 생체중과 건물중은 생육초기에는 NFT에서 무거웠으나 생육이 진전될수록 간헐침지식에서 더 무거워졌다. 3. 처리 후 43일의 개화수는 분무경 18.5, 15분간격 간헐침지식 17.8, 10분간격 간헐침지식 16.8, NFT 15.1개 순이었으며 과중은 분무경에서 149.1g으로 가장 무거웠다. 4. 식물체당 평균수량은 분무경에서 1929.1g으로 가장 많았고 10분간격 간헐침지식에서 1475.2g으로 다음이었으며, NFT식 및 15분간격 간헐침지식에서 각각 1276.2, 1084.8g으로 가장 적었다. 5. 식물체당 평균수호과수는 분무경 11.0, NFT식 9.7, 15분간격 간헐침지식 8.3, 10분간격 간헐침지식 7.7개 순이었으며 평균과중은 분무경 192.9, 10분간격 간헐침지식 172.4, NFT식 134.0, 15분간격 간헐침지식 126.0 순이었다. 6. 평균과장은 분무경과 10분간격 간헐침지식에서 NFT식과 15분간격 간헐침지식보다 길었으며 평균과폭은 NFT식, 분무경 및 10분간격 간헐침지식에서 비슷한 정도로 15분간격 간헐침지식보다 켰다.