• 한국융합학회논문지
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• 제10권4호
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• pp.131-138
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• 2019

디젤엔진은 열효율이 높고 연비가 좋으며 CO, HC 및 $CO_2$의 배출량이 낮은 등 가솔린 엔진보다 상당한 장점이 있다. 그러나 디젤엔진은 배기가스 중에 $O_2$ 농도가 높기 때문에 NOx 저감이 어렵고, 삼원촉매를 적용하기 어렵다. Urea-SCR과 LNT는 디젤엔진에서 NOx를 연속적으로 저감하는데 활용 가능한 두 기술이다. 디자인 엔진에 Urea-SCR 시스템을 구현함으로써 2.5l 이상 엔진에서 Euro-6의 강화된 NOx 기준을 충족시킬 수 있게 되었다. 본 연구에서는 엔진 회전속도, 부하, 촉매 방식 및 $NH_3$/NOx 비율에 따른 NOx 저감 특성을 연구하여 NOx 저감을 극대화하는 조건을 제시하고자 한다. 또한 Euro-6 이상의 규제에 대응할 수 있도록 Urea-SCR에 대한 정밀한 실험 데이터를 제공하고자 한다.

• 정보보호학회논문지
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• 제19권3호
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• pp.3-10
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• 2009

본 논문에서는 중국 무선 네트워크 표준 WAPI에 사용되고 있는 블록 암호 SMS4에 대한 향상된 차분 공격 및 선형 공격을 소개한다: 먼저, SMS4의 전체 32 라운드 중 20또는 21 라운드에 적용된 기존 차분 공격을 22 라운드 차분 공격으로 확장하는 방법을 소개한다. 또한 22 라운드로 축소된 SMS4에 적용된 기존 선형 공격의 복잡도, $2^{119}$기지 평문, $2^{109}$ 메모리 바이트, $2^{117}$의 암호와 과정을 새로운 선형 근사식을 이용하여 $2^{117}$기지 평문, $2^{109}$ 메모리 바이트, $2^{112.24}$ 암호와 과정으로 향상시킨다. 본 논문의 분석 결과는 SMS4에 대해 알려진 공격 중 최상의 공격이다.

• Membrane and Water Treatment
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• 제15권1호
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• pp.21-29
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• 2024

1H,1H,2H,2H-perfluorodecytriethoxysilane (C₁₆H₁₉F₁₇O₃Si) be successfully applied to the hydrophobic modification of Al₂O₃ tubular ceramic membrane. Taking the concentration of modification solution, modification time, and modification temperature as factors, orthogonal experiments were designed to study the hydrophobicity of the composite membranes. The experiments showed that the modification time had the greatest impact on the experimental results, followed by the modification temperature, and the modification solution concentration had the smallest impact. Concentration of the modified solution 0.012 mol·L^-1, modification temperature 30 ℃ and modification time 24 h were considered optimal hydrophobic modification conditions. And the pure water flux reached 274.80 kg·m^-2·h^-1 at 0.1MPa before hydrophobic modification, whereas the modified membrane completely blocked liquid water permeation at pressures less than 0.1MPa. Air gap membrane distillation experiments were conducted for NaCl (2wt%) solution, and the maximum flux reached 4.20 kg·m^-2·h^-1, while the retention rate remained above 99.8%. Given the scarcity of freshwater resources in coastal areas, the article proposed a system for seawater desalination using air conditioning waste heat, and conducted preliminary research on its freshwater production performance using Aspen Plus. Finally, the proposed system achieved a freshwater production capacity of 0.61 kg·m^-2·h^-1.

• International Journal of Computer Science & Network Security
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• 제23권7호
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• pp.16-22
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• 2023

Enhanced radio access technologies (RAT) are deployed in Next Generation Convergence Networks by the service providers so as to satisfy the basic requirements of end-users for e.g. QoS. Whenever the available resources are being shared simultaneously and dynamically by multiple users or distribution of allocated channels randomly, the deficiency of spectral resources and dynamic behavior of Network traffic in real time Networking, we may have problem. In order to evaluate the performance of our proposed algorithm, computer simulation has been performed on NS-2 simulator and a comparison with the existing algorithms has been made.

• International Journal of Computer Science & Network Security
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• 제23권11호
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• pp.133-141
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• 2023

This work take deeper analysis of Adaptive Moment Estimation (Adam) and Adam with Weight Decay (AdamW) implementation in real world text classification problem (DGA Malware Detection). AdamW is introduced by decoupling weight decay from L2 regularization and implemented as improved optimizer. This work introduces a novel implementation of AdamW variant as AdamW+ by further simplifying weight decay implementation in AdamW. DGA malware detection LSTM models results for Adam, AdamW and AdamW+ are evaluated on various DGA families/ groups as multiclass text classification. Proposed AdamW+ optimizer results has shown improvement in all standard performance metrics over Adam and AdamW. Analysis of outcome has shown that novel optimizer has outperformed both Adam and AdamW text classification based problems.

• 통상정보연구
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• 제10권2호
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• pp.283-304
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• 2008

According to globalization and localization of world economics international trade payment method was also changed. A traditional payment was Letter of Credit basis, however it is being increased to various methods such as remittance, documentary collection(D/P, D/A) and open account. In order to acquire a secure export payment, exporters prefer to L/C basis which is guaranteed by a reliable bank. However, the L/C should bear a security so that importers would rather documentary collection than L/C. The reasons for the preference of collection payment rather than L/C are a low commission cost, the conversion of buyer's market from seller's market due to severe competition in the world market, transaction increase between main office and branches and a right to control the goods until executing the payment by exporters. Besides of them, collection payment can handle safer and faster than open account basis. However, the collection payment has a risk which it isn't guaranteed by bank for the payment so that I would suggest countermeasures to minimize the payment risk utilizing the collection basis as follows; using export credit insurance system, a large domestic credit report provider such as D&B for absolutely fresh and new information, a collection proxy service for overseas deferred credit and suggestion specifying to order B/L not straight one on consignee in order to transfer the right of ownership with endorsement without problem.

• 상하수도학회지
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• 제32권4호
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• pp.309-315
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• 2018

Currently, the commercialization of the $5^{th}$ Generation (5G) service is becoming more prevalent in domestic communication network technology. This has reduced communication delay time and enabled large-capacity data transmission and video streaming services in real-time. In order to keep pace with these developments, K-water has introduced a smart process control system in water purification plants to monitor the status of the water purification process. However, since wireless networks are based on the public Long Term Evolution (LTE) network, communication delay time remains high, and high-resolution video services are limited. This is because communication networks still have a closed structure due to expense and security issues. Therefore, with 5G in its current form, it is very difficult to accommodate future services without improving the infrastructure of its communication networks. In recognition of these problems, this study implemented the authentication and management function of wireless networks on a wired network management system in the K-water Bansong water purification plant. The results confirmed that wired Local Area Network (LAN) services give a higher security performance than an expensive commercial wireless LAN system. This was achieved by using an Internet Protocol (IP) address management system of wired networks and the packet filtering function of the Layer2 (L2) switch. This study also confirmed that it is possible to create a wireless LAN service that is 3.7 times faster than the existing LTE communication network.

• 정보보호학회논문지
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• 제17권2호
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• pp.83-92
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• 2007

비 연결형 패킷 통신망에 Block Chaining 모드를 사용하여 통신패킷을 암호화하는 암호통신시스템에서 통신패킷의 송수신 순서가 달라지거나 통신패킷이 분실되면 암호 통신 성능 및 효율성이 저하된다. 이를 해결하기 위하여 통신패킷의 송수신 순서에 무관하게 암복호 처리 할 수 있는 고속 패킷통신을 위한 패킷 암호 스킴을 제안하였다. 제안한 패킷 암호 스킴은 키교환할 때 생성한 IV(Initial Vector)와 암호모듈 내부에서 난수로 만든 salt를 이용하여 새로운 IV를 만들고, 이 IV와 공통키를 사용하여 통신패킷별로 암호화한다. 패킷 암호 스킴을 적용하기 위한 패킷 암복호 함수 및 메커니즘을 추가한 확장된 Cryptoki를 제안하여 편리성과 성능을 개선하였다. 제안한 패킷암호 함수의 성능을 비교하기 위하여 암호모듈을 구현하였으며, 시험한 환경에서 패킷 암호 함수를 적용하여 20회 암호화하였을 때 기존 Cryptoki API에 비하여 약 1.5배에서 15.6배 정도의 성능 향상을 가져왔다.

• 정보보호학회논문지
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• 제32권2호
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• pp.213-225
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• 2022

컨테이너 기술은 클라우드 환경에서 마이크로서비스의 효율적인 구축 및 운영을 가능하게 했지만, 심각한 보안 위협도 함께 가져왔다. 다수의 컨테이너가 서비스 구성을 위해 네트워크로 연결되기 때문에 공격자는 탈취한 컨테이너에서 네트워크 공격을 수행해 인접한 다른 컨테이너를 공격할 수 있다. 이러한 위협을 막기 위해 다양한 컨테이너 네트워크 보안 솔루션이 제안되었으나 성능적인 측면에서 많은 한계점을 갖고 있다. 특히 이들은 컨테이너 네트워크 보안에 필수적인 패킷 페이로드 검사 과정에서 매우 큰 네트워크 성능 저하를 일으킨다. 본 논문에서는 이러한 문제를 해결하기 위해 클라우드 환경을 위한 eBPF/XDP 기반 고속 패킷 페이로드 검사 시스템인 BPFast를 제안한다. BPFast는 별도의 유저 수준 컴포넌트 없이 커널 영역에서 컨테이너가 전송한 패킷의 헤더와 페이로드를 검사하여 컨테이너를 네트워크 공격에서부터 보호한다. 본 논문에서는 Kubernetes 환경에서 진행한 실험을 통해 BPFast 프로토타입이 Cilium, Istio 등 최신 솔루션보다 최대 7배 더 빠르게 동작할 수 있음을 증명했다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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• pp.184-186
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• 2007

Visualization has a strong capability to manage and display a large volume of data. It makes system analysis more intuitive and helps an operator in monitoring system status, understanding its phenomena, identifying its problems, and performing corrective action to maintain the security of the system. In this paper visualization program is developed based on a COTS-based software development concept in a distributed environment using open-source application software and development tools.