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김승학(Seung-Hak Kim),김동환(Dong-Hwan Kim),정기현(Ki-Hyun Jung) 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.6
Steganography is a information hiding technique that embed the secret data into multimedia data like as text, image, audio and video. When malicious acts are combined with these technique, it is very difficult to detect. In this paper, we propose a technique to detect the secret data by analyzing packet on network.
김승학(Seung-Hak Kim),윤창민(Chang-Min Yoon),김대유(Dae-Yoo Kim),정기현(Ki-Hyun Jung) 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.6
With the development of computers and the Internet, security threats have also become more diverse and complex. It is necessary to make efforts to solve these problems efficiently. In this paper, various models of incident response are introduced and analyzed, and a new optimal model is proposed. The proposed model consists of preparation, detection and initial countermeasure, collection and analysis, and remove infection and recovery processes.
2관능성 에폭시/생분해성 폴리부틸렌 숙시네이트 블렌드의 유변학적 특성 및 경화거동에 관한 연구
박수진 ( Soo Jin Park ),김승학 ( Seung Hak Kim ),이재락 ( Jae Rock Lee ),민병각 ( Byung Gak Min ) 한국복합재료학회 2002 Composites research Vol.15 No.6
본 실험에서는 2관능성 에폭시 수지(2EP)와 생분해성 poly(butylene succinate)(PBS) 블렌드의 유변학적 특성, 경화거동, 열안정성 그리고 기계적 특성을 살펴보았다. 유변학적 특성은 레오미터를 이용하여 등온 조건 하에서 검토하였고, 젤화 시간과 경화 온도를 이용한 Arrhenius 방정식을 적용하여 가교 활성화 에너지(E_c)를 구하였다. E_c는 2EP에 대한 PBS의 비율이 10 wt%로 증가함에 따라 증가하였다. DSC 측정 결과, 경화 활성화 에너지(E_a)는 E_c와 유사한 경향을 나타내었는데 이는 2EP와 PBS 사이의 분자상호작용이 증가하였기 때문으로 사료된다. 그리고 열안정성과 관련하여 분해 활성화 에너지(E_t)는 Horowitz-Metzger식을 이용한 적분법을 사용하여 구하였는데 PBS 10 wt%에서 증가하였다. 그리고 20 wt% PBS일 때 가장 높은 임계응력세기 인자를 보이는데, 이는 2EP/PBS 블렌드 시스템의 파괴인성이 증가하였기 때문으로 사료된다. In this work, the effect of biodegradable poly(butylene succinate)(PBS) in difunctional epoxy(2EP) resin was investigated in terms of rheological properties, cure kinetic, thermal stabilities, and mechanical interfacial properties. Rheological properties of the blend system were measured under isothermal condition using a rheometer. Cross-linking activation energies(E_c) were determined from the Arrhenius equation based on gel time and curing temperature. The Ec was increased in the presence of 10 wt% PBS as compared with neat 2EP. From the DSC results of the blends, the cure activation energies(E_a) showed a similar behavior with Ec due to the increased intermolecular interaction between 2EP and PBS. The decomposed activation energies(E_t) for thermal stability derived from the integral method of Horowitz-Metzger equation, were also increased in 10 wt% PBS. In addition, 20 wt% PBS showed the highest critical stress intensity factor(K-IC), which was explained by increasing the fracture toughness of the 2EP/PBS blend systems.
Polysulfide 前處理에 의한 Cyanide 含有廢水의 活性汚泥處理
金承鶴,李武康,韓基白 慶星大學校 環境問題硏究所 1992 環境硏報 Vol.2 No.1
The objective of this study was performed in order to obtain the changing efficiency of SCN- according to and reaction time. For that reason, the polysulfide was added to the cyanide wastewater in a fixed weight ratio. Herewith the design parameter was determined for the synthetic wastewater containing 300㎎/ℓof SCN- and was compared substrate removal constant(k) with adsorption reaction constant(k₁k₂) by adsorption equilibrium eqtion. The changing rate of CN- to SCN- was found to be pH 10, pH 12 for 90∼95 percent within 3 hours. On other hand, was found to be pH 7 for 60∼65 perdent due to the Polysulfide precipitating. On the occasion of 10, after the reaction time proceeded 3 hours, pH of bulk solution was varied from 10 to 7. But practically changing of SCN concentration was not significant. Treatment of the synthetic wastewater containing 300㎎/ℓof SCN- at 20±1℃ with the Hydraulic retention tin of 6 to 18 and MLVSS concentration of 3050 to 3590㎎/ℓgave 94.2∼96.5 percent in substrate removal efficiencies as COD . The design parameters of k, Y, ke, Vmax and Km were determined to 0.0247 d-1, 0.2119, 0.0561 d-1, 4 d-1, and 153.96㎎/ℓ. In adsorption teste using acclimated sludge, adsorption removal rate was 0.5476㎎/㎎ MLVSS. day at 314㎎/ℓ initial SCN- concentration and was 0.3045㎎/㎎ MLVSS·day at 576㎎/ℓ of initial SCN- concentration. It was adapted adsorption equilibrium equation for substrate removal by the activated sludege. In the results, Freudlich's adsorption reaction constant, k₁ was 0.0273 day-1 and n₁was 0.840 and Katz's adsorption reaction constant, k₂ was 0.0287 day-1 and n₂was 0.839. These values were similar in comparison with the substrate removal constant(k=0.247).
생분해성 폴리락타이드/폴리에틸렌글리콜 공중합체 마이크캡슐의 제조와 방출거동에 대한 연구
박수진,김승학,홍성권 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.4
본 연구에서는 생분해성 poly(L-lactide) (PLA)/poly(ethylene glycol) (PEG) 마이크로캡슐을 액중건조법으로 제조하고, PLA 마이크로캡슐에 PEG를 첨가함에 따른 분해거동, 크기분포 그리고 방출거동에 미치는 영향을 살펴보았다. 그 결과, PLA/PEG 공중합체는 PLA보다 친수성이 크게 나타났고, 낮은 유리전이 온도를 가짐을 알 수 있었다. PLA/PEG 마이크로캡슐의 표면은 PLA 마이크로캡슐보다 부드럽지 못했고, 제조된 PLA와 PLA/PEG 마이크로캡슐의 평균크기는 40과 57 ㎛이었으며, 또한 구형의 형태를 나타내는 것이 image analyzer와 SEM을 통하여 관찰되었다. PLA/PEG 마이크로캡슐의 약물 방출거동은 UV/Vis. spectra를 통하여 살펴보았고, 방출 속도는 PEG의 첨가에 따라 두드러지게 증가하였는데, 이는 친수성기의 증가와 PEG의 팽윤성으로 설명되어질 수 있다. In this work, biodegradable poly(L-lactide) (PLA)/poly(ethylene glycol) (PEG) microcapsules were prepared by emulsion solvent evaporation method. The effect of PEG segments on the degradation, size distribution, and release behavior of the microcapsules was studied. According to the experimental results, PLAPEG copolymers were more hydrophilic and exhibited lower glass transition temperatures compared to PLA homopolymer. The surface of PLAPEG microcapsules was not as smooth as that of PLA microcapsules. The mean diameters of the PLA and PLA/PEG microcapsules were 40 and 57 pm, respectively. The spherical forms were observed by image analyzer and scanning electron microscope (SEM). Drug release from microcapsules was determined by UV/Vis spectra. It was found that the drug release rates of the microcapsules were significantly increased with adding of PEG, which could be attributed to the increase in their hydrophilicity and swelling characteristics.