• Journal of KIISE:Computing Practices and Letters
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• v.9 no.3
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• pp.311-321
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• 2003

A current firewall or IDS (intrusion detection system) of the network level suffers from many vulnerabilities in internal computing servers. For a secure Linux implementation using system call hooking, this paper defines two requirements such as the multi-level security function of TCSEC B1 and a prevention of hacking attacks. This paper evaluates the secure Linux implemented in terms of the mandatory access control, anti-hacking and performance overhead, and thus shows the security, stability and availability of the multi-level secure Linux. At the kernel level this system protects various hacking attacks such as using Setuid programs, inserting back-door and via-attacks. The performance degradation is an average 1.18% less than other secure OS product.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.4
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• pp.112-121
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• 2009

To obtain basic design criteria for underground anaerobic digestion and enhance biogas production from swine slurry, a $20m^3$ underground anaerobic digester (UGAD) was constructed and operated at mesophilic ($31{\sim}37^{\circ}C$) temperature with an organic loading rate (OLR) at $23.6kgVS/m^3/day$. The average biogas and $CH_4$ production rate were observed at 8.62 and $5.78m^3/day$, respectively. The mean percentile of $CH_4$ and $CO_2$ were also observed at 67.5% and 19.6%. The relative biogas yield was explored at $733L/kg\;VS_{added}$ and $CH_4$ yield was at $495L/kg\;VS_{added}$ respectively. The removal rate of biochemical constituents and pathogens were noticed considerably at 68%, 74%, 79%, 86%, 89%, 81%, 55%, 79%, 98% and 100% on TS, VS, TSS, $BOD_5$, $TCOD_{cr}$, $SCOD_{cr}$, $NH_3-N$, available P, fecal coliforms and Salmonella, respectively. This study suggested that, the modified UGAD system is a greatly desirable for anaerobic digestion for swine slurry with regards to high methane yield and biodegradability.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.71.2-71.2
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• 2011

300MW 급 태안 IGCC 가스화 플랜트 및 기존 발전소에 CCS 를 설치할 경우에 대해 기술 타당성 검증을 목적으로 CCS 모델링을 수행하였다. CCS Case Studies 는 플랜트 운전부하에 따른 $CO_2$ 제거율, $H_2S$ 제거율, 소모동력 범위 등 플랜트 성능을 예측할 수 있다. Case Studies 결과를 활용하여 설계된 CCS 설비 용량이 운전범위에 적합한지를 판단할 수 있고 과잉 설계되었을 경우 플랜트 건설비를 절감할 수 있다. IGCC 가스화 플랜트에서 생산되는 합성가스의 $CO_2$ 분압, 목표 $CO_2$ 제거율, 경제성을 기준으로 적합한 CCS 공정을 판단한 결과 Selexol 공정이 선정되었다. Selexol 공정은 고압, 고농도의 산성가스 제거에 적합하며 다른 물리적 용매인 Rectisol 공정에 비해 건설비용이 경제적이고 화학 흡수제인 아민과 비교하여 운전 온도 범위가 넓다. CO, $H_2O$ 를 $CO_2$, $H_2$ 로 전환하는 Water Gas Shift Reaction (WGSR) 공정은 Co/Mo 촉매 반응기로 구성되었고 Selexol 공정은 $H_2S$ Absorber, $H_2S$ Stripper, $CO_2$ Absorber, $CO_2$ Flash Drum 로 구성되었다. WGSR+Selexol 모델링은 Wet Scrubber 후단의 합성가스 (40.5 bar, $136{\sim}139^{\circ}C$) 를 대상으로 하였다. WGSR+Selexol 공정 운전 조건 변화 [Process Design Case(PDC), Equipment Design Case(EDC), Turndown Design Case(TDC)] 에 따른 플랜트 모델링 결과를 비교분석 하였다. 주요 분석 내용은 WGSR 설비에서의 CO 의 $CO_2$ 전환 효율, Selexol 설비에서 $CO_2$ 제거 효율, $H_2S$ 제거 효율이다. 모델링 결과 WGSR 설비에서의 CO 의 $CO_2$ 로의 전환율 99.1% 이상, Selexol 설비에서 $CO_2$ 제거율은 91.6% 이상, $H_2S$ 제거율 100%이었다. CCS 설비 설치에 따른 플랜트 성능 영향을 분석하기 위해서 CCS 설비의 Chiller, Compressor, Pump 소비동력을 계산하였다. 모델링 결과 Chiller 는 2.6~8.5 MWth, Compressor 는 3.0~9.6 MWe, Pump 는 1.4~3.0 MWe 범위 이었다. 플랜트 로드가 50%인 TDC 소모동력은 플랜트 로드가 100%인 PDC 소모동력의 절반 수준이었다. 합성가스를 WGS+Selexol 공정을 통해 수소가스로 전환시키면 가스터빈 연료가스의 Lower Heating Value (LHV) 값이 평균 11.5% 감소하였다.

• Korean Journal of Ecology and Environment
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• v.35 no.1 s.97
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• pp.28-35
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• 2002

The effect of physical parameters on water quality was analyzed using monitoring data of 193 agricultural reservoirs. The retention time of reservoirs ($t_d$) ranged between 10 and 140 days, and the ratio of drainage area (DA) to reservoir surface area (SA) was between 10 and 120. Both ratios of DA/SA and total area (TA)/ reservoir storage (ST) in Korean agricultural reservoirs were relatively greater than those in natural lakes in other countries. As retention time was plotted against DA/SA ratio, it was shorter in Korean reservoirs than natural lakes. The semi-logarithmic relationship between TA/SA and t>$t_d$ was $t_d\;=\;42.21(TA/ST)^{-1}$ (n = 50, $R^2\;=\;0.89$). While areal loading of total phosphorus (TP) was below $4\;gTP{\cdot}m^{-2}{\cdot}yr^{-1}$ in general, it exceeded $10\;gTP{\cdot}m^{-2}{\cdot}yr^{-1}$ in reservoirs where DA/SA ratio was greater than 100, which implies that areal loading of TP increases as DA/SA ratio increases. Chl-a concentration was positively related with the mean depth of reservoir, implying the higher Chl-a concentration with deeper the mean depth. Therefore, the deeper reservoir might be advantageous in water quality management perspective if other morphological conditions are similar. The empirical regression equation using physical parameters was also suggested in the estimation of TP concentration in the reservoirs. Combined information presented in this paper might be applicable to the water quality management in agricultural reservoirs.

• Journal of Life Science
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• v.20 no.3
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• pp.437-443
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• 2010

This study was designed to examine the aerobic capacity and ventilatory response during an incremental exercise in elite high school cyclists. Twelve boys ($17{\pm}1\;yr$, $175{\pm}5\;cm$, $70{\pm}9\;kg$) participated in anthropometric measurements, incremental exercise testing, and pulmonary function tests. During incremental exercise testing using a cycle ergometer, their maximal oxygen uptake ($VO_2max$), maximal power output, ventilation, ventilatory equivalents for oxygen ($V_E/VO_2$) and carbon dioxide ($V_E/VCO_2$), respiratory rate, and tidal volume were measured. Time variables such as inspiratory time (Ti), expiratory time (Te), breathing time (Tb), and inspiratory duty cycle (Ti/Tb), as well as inspiratory flow rate ($V_T$/Ti) were assessed. Pulmonary function of vital capacity (FVC), forced expiratory volume in one second ($FEV_1$), $FEV_1$/FVC, and peak expiratory flow were evaluated. Their $VO_2max$, maximal heart rate, and Wmax were $57.5{\pm}3.9\;ml{\cdot}kg^{-1}{\cdot}min^{-1}$, $194.1{\pm}8.6\;beat{\cdot}min^{-1}$, and 452 W, respectively. $VO_2max$ was not related to any anthropometric parameters. Most ventilatory variables progressively increased with exercise intensity. As intensity increased, Ti, Tb, Tb decreased while Ti/Tb was maintained. Below an intensity of 250 W, height, weight, body mass index, and body surface were highly correlated with $V_T$/Ti and Ti/Tb (p<0.05). Collectively, $VO_2max$ appeared to be lower than adult cyclists, suggesting a different pattern of ventilatory control as age advances. Morphological characteristics were not related to $VO_2max$ in the population. Time variables of ventilatory response seemed to be related only at an exercise intensity level of less than 250 W. $V_T$/Ti may be related to exercise endurance capacity, but Ti/Tb was similar to adult cyclists.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.3
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• pp.172-177
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• 2014

Low pressure air flotation (LAF) pilot plant for sludge thickening was installed in Chung Nam N.S. municipal waste water treatment plant to verify its application possibility. Effects of operating conditions such as coagulant dosages and microbubble water ratio on thickening of the mixed sludge were examined. Microbubbles which were generated in the chamber of $1.5kgf/cm^2$ by high speed collision method with foaming agent were used to float sludge. Solid loading of $30kg/m^2/hr$, solid contents in thickened sludge of 60,300 mg/L and SS removal efficiency of 99% were obtained through long period operating LAF in conditions of mixed sludge concentration of 14,400 mg/L, coagulant dosage of 27.6 mg/L, foaming agent addition of 4.0 mg/L and microbubble water injection ratio of 9.7%.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.666-672
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• 2008

Feasibility of simultaneous removal of organic matter, nitrogen and phosphorus was evaluated by applying AO$_2$ system to treat wastewater from a seafood processing plant. Treatability test was conducted by incorporating activated sludge from municipal sewage treatment plant with PU-AC media. Inflow concentrations of COD, TN, and TP were 198$\sim$1,240 mg/L, 75$\sim$577.4 mg/L, and 2.2$\sim$53.5 mg/L, respectively. Average removal efficiencies and outflow concentration of COD, TN, and TP were 86.5%, 65.7 mg/L; 81.4%, 53.1 mg/L; and 80.6% 4.07 mg/L, respectively. Stable operation was possible by increasing organic matter, nitrogen, and phosphorus loading rate to seafood wastewater treatment system composed of anaerobic and aerobic reactors. Used PU-AC media was proved to be biodegradable in this AO$_2$ system by maintaining high biomass concentration in the PU-AC media.

• Convergence Security Journal
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• v.7 no.1
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• pp.77-82
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• 2007

Supporting Quality of Service (QoS) for multimedia services in heterogeneous mobile networks is a part of key issue for Beyond Three Generation (B3G) development. In particular, if QoS degradation are occurred because cell overload and error late patterns of wireless links during the transmission of multimedia data, the efficient QoS management is necessary to maintain the same QoS of transmitted multimedia data because the QoS may be defected by some delay and information loss. This paper deals with QoS Degradation reason Intra-System Handover (D-ISHO) for handling QoS of multimedia services over heterogeneous mobile networks. For this aim, the function modules for supporting QoS of D-ISHO are proposed. The sequence diagram showing interaction between the modules is described and then a scenario for D-ISHO is considered. Simulation is focused on the average delay and packet loss rate. The proposed heterogeneous mobile system using the QoS-Guaranteed Resource Management (QGRM) provides a better performance than each different access system.

• Journal of Wetlands Research
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• v.12 no.3
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• pp.39-47
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• 2010

Annually, the scale of agricultural areas in Korea were being reduced as the lands were converted to other land uses. While the rate of productivity were either being maintained or increased, the pollution load from these areas were still greater in magnitude. Although the levels of pollutant concentration released in the agricultural watersheds were minimal, the combined quantities mostly from diffuse sources were high. As a consequence, the Ministry of Environment (MOE) in Korea adopted the use of free water surface (FWS) flow constructed wetlands to reduce the pollutant loadings emitted from agricultural watersheds for the improvement of water quality and protection of aquatic ecosystems. In this study, a constructed wetland treating stream water in an agricultural watershed was monitored since April 2009 subsequent to its completion in December 2008. Satisfactory performance was achieved for TSS, BOD and TP with 26%, 28% and 39% pollutant removal rates, respectively. In addition, the effluent water quality was improved and achieved compliance the national water quality criteria. Results of this study can be useful to establish design parameters and employ proper removal techniques of similar natural treatment systems for future implementation in the country.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.463-471
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• 2019

The purpose of this study was to investigate the effect of muscle imbalance on motion of back squat. The isokinetic muscle strength of the 8 subjects was recorded for the knee flexion/extension by the cybex 770 dynamometer. Each subject performed 3 back squats with the long barbell with an intensity of 25% body weight(BW), 50%BW, 100%BW, 125%BW. During the back squat through the recorded kinematic data the subjects' maximum flexion and extension knee angle, center of mass displacement and V-COP were calculated for evaluation of the stability of the movement. For the statistical analysis independent t-test was used. Knee flexion angle and COM displacement are dominated by the reciprocal muscle ratio. V-COP factor was dominated by bilateral extension deficit. Based on the results we can know that as the intensity of the squat increased to a level control was difficult because the muscles' imbalance influenced the movement.