최근, 전세계적으로 물 부족 현상과 지역개발 및 산업 고도화, 인구증가와 함께 물 수요는 증가하고 있다. 이를 해결하기 위한 방법으로 해수담수화 방법이 있다. 해수 담수화의 많은 방법 중 이온 교환막을 이용한 실험을 진행하였다. 본 연구에서는 Anion exchange resin을 대체할 수 있는 물질로 Polystyrene Latex입자를 제조 하였다. 제조된 입자에 chloromethylation과 amination을 통해 –NH3+, -NR3+, -PR3+, -SR2+등의 관능기를 도입하였으며, 제조된 입자와 고분자를 합하여 하이브리드 막 제조를 하였다. 특성평가로는 SEM, TGA, DSC, FT-IR, IEC Value를 통한 측정을 진행하였다.

제련 산업 공정에서 다량 방출되는 폐산 용액에는 다양한 유가 및 희소 금속을 함유하고 있으며 분리 및 회수 기술 부족으로 중화법을 통해 폐기되고 있다. 이에 본 연구에서는 폐산에 존재하는 금속들을 경제적으로 회수하기 위해 막분리 공정을 적용하고자 내산성 나노분리막을 제조하였다. 나노분리막은 다공성 PSf 지지막 위에 amine과 trimesoyl chloride (TMC)를 계면중합하여 제조하였다. 분리막의 투과 평가는 75psi 압력 하에서 cross-flow 방식으로 진행하였으며 내산성 평가는 15 wt% 황산 용액에 일별 노출한 후 투과 평가를 진행하였다. 제조막의 특성은 FTIR, XPS, FE-SEM의 분석 통해 확인하였다.

본 연구에서는 혼합기체 투과 시 높은 CO2 선택도 특성을 가지는 분리막을 제조하기 위한 연구를 하였다. 이를 위해 Polyhedral Oligomeric Silsesquioxane(POSS)와 Polyethylene glycol(PEG)의 추가적인 합성을 진행하여 POSS-PEG를 얻었다. 또한 투과도와 선택도를 향상시키기 위해 POSS-PEG를 용매에 희석시켜 추가적인 코팅을 진행하여 복합막을 제조하였다. 특성평가 진행은 POSS-PEG Film의 기체투과 특성을 측정하기 위해 Time lag를 사용하였으며, N2, O2, CO2를 혼합한 혼합기체에 대한 특성평가는 Bubble flowmeter와 Gas chromatography를 이용하여 진행하였다.

In this study, the mechanical characteristics with micro structure were analyzed on the butt joint of AZ60 magnesium material extruded by GMAW and GTAW processes. As the result of tensile test, the fracture in the welding joint area happened at both processes and seemed to be brittle fracture. The yield strength of GMAW was 84.29% and GTAW was 60.43% as compared with base metal. The yield strength of GMAW was higher 23.86% than that of GTAW. The result of decreased micro hardness was indicated at both processes. The value of minimum micro hardness in FZ at GMAW was Hv 46.7 and GTAW was Hv 43.6 as compared with base metal. The value of minimum micro hardness at GMAW process was higher 5.64 % than that at GTAW process. The size of grain boundary at GMAW process in HAZ is smaller than that at GTAW process. GMAW process is more superior than GTAW process from the productivity and quality in case of automatic welding for magnesium alloy such as the automobile seat frame.

P92 steel weldment scheduled to use for next generation ultra super critical(USC) boiler header is assessed on creep characteristics. The test method to assess local structure of weldment is small-punch creep(SP-Creep) test, which is a kind of micro test proved the availability on evaluation of mechanical property for local structure. The results for P92 steel weldment are compared with that of tensile creep test for same microstructures of steel weldment. Overall, the creep resistance of coarse grain HAZ(CGHAZ) at 650℃ is inferior to the other structures while fine grain HAZ(FGHAZ) is most superior in the P92 steel weldment. The power law relationships can be obtained for each weldment structures(BM, ICHAZ, FGHAZ, CGHAZ and W.M) of USC boiler header

This study undertook to evaluate the quality characteristics of rice, to select a variety suitable for porridge. Seven varieties of rice were studied: Dabo, Daebo, Samkwang, Sindongjin, Sukwang, Jinsumi and Haiami were investigated for proximate contents and physicochemical characteristics. The moisture and crude protein contents of the rice cultivars were in the range 11.26-12.66% and 5.34-6.47%, respectively. The amylose content was the highest in the Samkwang (20.83%), and lowest in Haiami (18.32%). The water binding capacity and solubility of Samkwang and Jinsumi cultivars were greater than those of the other samples. Hardness of rice and viscosity of porridge was the least in Samkwang and Sukwang. The pH of porridge in Samkwang and Jinsumi (7.04) was higher than the other varieties (6.80-7.03). The results of this study indicate that Samkwang and Jinsumi are suitable varieties for porridge. We expect this data will be useful in the manufacturing of porridge.

본 연구는 gum arabic의 농도에 따른 계면흡착특성과 에멀션의 유화 안정성을 평가하고, gum arabic을 이용한 에멀션 제조 및 안정성을 확인하였다. Gum arabic 농도별(10-4~0.2 wt%)로 계면장력을 측정하여 계면활성능력을 확인 한 뒤, 10 wt%의 palm oil에 대한 농도별(2.0~4.5 wt%) 에멀션의 안정성을 37일 동안 관찰하였다. Gum arabic의 유화능을 측정하기 위해 표면장력계, 입도분석, Turbiscan, 현미경을 이용하여 관찰하였다. Gum arabic의 경우, 농도가 증가할수록 계면장력이 감소하는 경향을 확인할 수 있었다(0.2 wt%, γ ≈ 33.2 mN m-1). 유화액 시스템(팜유 10 wt% in water phase)에서는 4.0 wt%(d43 ≈ 0.54 μm, d32 ≈ 0.32 μm) 이상의 농도에서는 37일 동안의 크기의 변화가 없는 것을 확인할 수 있었다. Gum arabic의 적정농도(≧3.5 wt%)를 결정한 후, 정제수 및 물엿을 이용해 고형분 45 wt%로 조절하여 유화액 분말를 제조하였다. 그리고 제조된 유화액 분말은 분말입자 크기와 지방 용출도로 안정성을 평가하였다. Gum arabic의 농도에 따라 분말입자의 크기는 유의적 차이가 없었으나(d43 ≈ 44.85 μm, d32 ≈ 28.88 μm), Gum arabic 4.0 wt% 이상 함유한 커피크리머는 제조 수율(99.5%)이 높고, 지방 용출도(4.65%)가 낮은 것을 확인할 수 있었다. 따라서, gum arabic이 기존 유화액 제조 시 사용되는 합성유화제를 대체 할 수 있음을 확인하였다.

The durability degradation of concrete pavement by winter deicer is brought up as a significant risk, and its maintenance brings a high expense. Therefore, a proper repair materials for such concrete pavement are required. In this study, the properties of compressive strength, ability to resist chloride ion penetration, and dry shrinkage of Chemically bonded ceramics(CBC) and Calcium Sulfo Aluminate based ultra rapid harding cement(CSA) were assessed to evaluate its applicability as a repair material of concrete pavement road. As a result, the CBC mortar flow showed a 220㎜, and the initial setting time of CBC was 18 minutes. The compressive strength of CBC mortar was 31.3㎫ in 2 hours, 56.6㎫ in 24 hours, and 79.1㎫ in 28 days, showing a significant level. And the ability to resist chloride ion penetrations of CBC showed 433 Coulombs, which fell under very low level. The drying shrinkage of CBC mortar until 56 days was between 150 × 10-6 with -100 × 10-6, showing a significant very low level. As above, CBC has excellent compressive strength, chloride ion penetration resistance, and volume stability, and showed better performance than CSA. Therefore, CBC in the future could be used in repair of concrete pavement.

This study was conducted to estimate the growth parameters of Holstein cows and to compare their growth characteristics based on weight-age data of Holstein cows of 293 heads from National Institute of Animal Science in Korea. Three models(Gompertz, von Bertalanffy and Logistic model) were considered for analyses. The estimated growth functions for Gompertz, von Bertalanffy and Logistic models were Wt=781.0e−2900e−0.09521t,Wt=943.3(1−0.650e−0.06231t)3 and Wt=665.7(1+13.475e−0.18260t)−1 , respectively. The estimated average infection points(ti) showing maximum growth rate were 352.034, 338.181 and 430.987 day of age, respectively, using on Gompertz, von Bertalanffy and Logistic model. Average gain at inflection for Gompertz, von Bertalanffy and Logistic model were estimated 0.878, 0.833 and 0.986 kg/day, respectively. The estimated weight at inflection for Gompertz, von Bertalanffy and Logistic model were 301.5, 279.5 and 332.9 kg, respectively. In the study, the von Bertalanffy model having a variable point of inflection fitted the best for data of Holstein cows.

This study investigates dynamic characteristics of a 2MW wind turbine structure by long-term response monitoring with accelerometers, tiltmeter and strain gauges. The object wind turbine structure is located in Jeju Island, Korea. The natural frequency and damping ratio were evaluated by least-square frequency domain decomposition and random decrement technique using acceleration response data. As a result, it was found that natural frequencies with 1st, 2nd and 3rd modes, and blade passing frequencies with 1P, 2P and 3P were clearly showed from power spectral densities of acceleration reponses. Furthermore, 1st model frequencies were almost constant with increase in standard deviations of acceleration responses. Another notable observation was that when standard deviations of acceleration responses were small, damping ratios showed to diverge. However, when standard deviations of acceleration responses had large values, damping ratios were converged to about 0.5%.

This study presents the behavioral characteristics of submerged floating tunnels under harsh environmental conditions. To evaluate the dynamic characteristics of the submerged floating tube moored by tethers, hydrodynamic analysis was performed in time-domain. To consider the irregular wave loading condition, JONSWAP wave spectrum was used with specific significant wave height and peak period. For applying the irregular wave in the explicit dynamic analysis procedure, equivalent regular wave components which have same wave energy were applied to the external force term with random phases. According to this study, lateral and vertical motion can be effectively controlled by adjusting initial tether angle and draft. Evaluation of fatigue damage of mooring lines can be conducted by analyzing the dynamic structural stresses with appropriate S-N curves and stress concentration factors. This study also dealt with short-term fatigue analysis for checking the tethers. According to this study, cumulative fatigue damage of the tethers is definitely affected by the essential design factors such as design draft of the tunnel and tether arrangement.

PURPOSES:The objectives of this study are to evaluate moisture sensitivity of various asphalt mixtures and to suggest an alternate method for the dynamic immersion test, which is used to determine the application of anti-stripping agent, by analyzing bond strength.METHODS:The bond strength of various asphalt mixtures such as hot mix asphalt, warm mix asphalt, and polymer-modified asphalt was evaluated by the ABS test. In order to characterize moisture sensitivity at different temperatures of the mixtures, the ABS test was conducted at -10°C, 5°C, 20°C, 40°C, and 54°C under both dry and wet conditions. The concept of the bond strength ratio was applied for objective moisture sensitivity analysis. Moreover, the bond strength characteristic was compared to the dynamic immersion test to suggest an alternate method to determine the application of anti-stripping agent.RESULTS AND CONCLUSIONS :Overall, the polymer-modified asphalt demonstrates the highest bond strength characteristic regardless of moisture condition and temperature. The bond strength characteristic displays a highly reliable linear relationship from 5°C to 40°C, and the relationship could be used to predict bond strength at any intermediate temperature. Based on the analysis of bond strength and retained asphalt ratio, the bond strength value of 1254 kPa could be applied as a criterion for anti-stripping agent.

Vortex-induced vibration and instability vibration of tall buildings are very important fluid-structure interaction phenomenon, and many fundamental questions concerning the influence of body movement on the unsteady aerodynamic force remain unanswered. For tall buildings, there are two experimental methods to investigate the characteristics of unsteady aerodynamic forces, one is forced vibration method and the other is free vibration method. In the present paper, a free vibration method was used to investigate the unsteady aerodynamic force on tall building whose aspect ratio is 9 under boundary layer simulating city area. Wind pressures on surfaces and tip displacements were measured simultaneously, and the characteristics of tip displacements and generalized forces were discussed. It was found that variation of across-wind displacements showed different trend between the case when wind speed increases and wind speed decreases, and the fluctuating generalize forces in across-wind direction of vibrating model are larger than that of static model near the resonant wind speed and approach to the static value. And for higher wind speed range, there were two peaks in across-wind power spectra of generalize forces of vibrating model, which means that two frequency components are predominant in unsteady aerodynamic forces.

PURPOSES:The purpose of this paper is to evaluate interface performance while using various tack coat materials for asphalt overlay.METHODS:The evaluation was conducted with tracking test, permeability, and interface bond strength. Tracking test was conducted using an image processing technique, to investigate the susceptibility of the tack coat materials. BBS and pull-off test were conducted to evaluate bond strength. The permeability test was conducted to evaluate the effect of tack coat materials.RESULTS :Results reveal that the trackless tack coat material demonstrates less tracking compared to other materials. Moreover, both BBS and pull-off tests can effectively evaluate the bond strength at the interface. RSC-4 was measured less bond strength. Moreover, tack coat prevents water penetration through the surface and aids the extension of the surface life of asphalt pavement.CONCLUSIONS :Trackless tack coat demonstrated a high and consistent bond strength performance. The tack coat types demonstrate marginally different performance as function of curing times. Field applicability was tested based on visual observation. Therefore, these should be considered when trackless tack coat is slightly enhanced the pavement performance based on limited this study results. Finally, it is necessary to allow reasonable time for the tack coat to completely cure.

본 연구에서는 리튬이온전지용 친수화된 세퍼레이터의 전기화학적 성능에 대한 연구를 진행하였다. 리튬이온전지 용 분리막으로 사용되는 폴리올레핀 소재는 소수성이고, 카보네이트 계열의 유기용매를 사용하는 전해액은 친수성을 가진다. 따라서 리튬이온전지는 수계전해액을 사용하기 때문에 폴리올레핀계 분리막에 다양한 친수성 고분자를 도입하여 친수화 처 리하였다. 코팅된 세퍼레이터의 변화를 평가하기 위해, 표면 관찰, 코팅시간에 따른 친수화도, 다공성, 젖음성에 대한 특성평 가를 수행하였다. 최종적으로 리튬이온이 코팅된 세퍼레이터의 저항과., 이온전도도를 측정하여 리튬이온전지 성능평가를 진 행하였다. PMVE로 코팅한 세퍼레이터의 친수화 정도가 우수하며, 세퍼레이터의 기공이 잘 유지되어 우수한 이온전도도를 나타냄으로써 이차전지 배터리에 적용을 위한 잠재성을 가짐을 확인하였다.

최근 전 세계적으로 급속한 도시화, 인구증가 및 기후변화에 따른 물의 수요와 공급의 불균형으로 인해 물 산업 의 경제, 사회, 환경적 중요성은 더욱 증가하고 있다. 이러한 물 산업은 크게 해당 분야에 따라 사용되는 분리막의 종류가 상 이하다. 주로 물리적, 화학적 안정성이 매우 우수한 고분자 소재가 사용되고 있으나, 이들 고분자들의 소수성인 성질 때문에 친수성을 부여하는 다양한 방법들이 소개되고 있다. 본 연구에서는 상용화되어 있는 중공사 지지체에 총 4종류의 친수성 고 분자들을 도입하여 친수성을 부여하였고, 주사전자현미경을 통해 코팅된 중공사 지지체의 모폴로지를 확인하였다. 또한, 각 고분자들로 코팅한 중공사 지지체의 친수화 정도를 알아보기 위해 접촉각을 측정하였고, 마지막으로 코팅 시간에 따른 수투 과도 변화 그리고 친수성 고분자에 따라 수투과도에 미치는 영향을 확인하였다. 그 결과 Pluronic 1 wt%로 코팅하였을 때 친 수화 정도가 우수하며 중공사의 기공을 막지 않고 우수한 수투과도 정도를 나타내 수처리 분리막으로 가장 적절하다는 결론 을 얻을 수 있었다.

본 연구는 YorkshireⅹLandraceⅹDuroc(YLD), YorkshireⅹChester whiteⅹYorkshire(YCY), and YorkshireⅹBirkshireⅹDuroc(YBD) 삼원교잡종 목심의 육질특성을 비교하여 새로운 교잡종 생산을 통한 품종개량에 필요한 기초적 자료로 이용하고자 이화학적 분석 및 관능 평가를 실시하였다. 돈육은 출하체중 110-120kg의 규격돈으로서 교잡종 별로 10두씩 임의로 선택하여 도축 후 24시간 동안 0±1℃예냉실에서 냉도체를 만든 후 좌도체로부터 돈육 목심 부위를 발골 및 정형하여 진공포장 후 일반성분 분석, 이화학적 분석 및 관능검사를 실시하였다. 일반성분 분석결과, YLD 교잡종 목심의 지방함량이 다른 교잡종에 비해 높았다(p<0.05). 육색지수의 경우 YLD 교잡종 목심의 L*값이 가장 높았다(p<0.05). 가열감량의 경우 YBD 교잡종이 다른 교잡종에 비해 높았지만, 다른지표들은 낮았다(p<0.05). 저장기간별 YCY의 TBARS 수치가 저장 14일차에 다른 교잡종보다 가장 낮았다(p<0.05). 관능검사의 경우 YLD와 YCY 교잡종이 더 높은 값을 나타내었다. 따라서 본 연구결과를 통해 보수력이 뛰어나고, 전단력가는 낮으며, 지방함량은 높아, 결국 가장 훌륭한 관능검사 결과를 얻은 YLD 교잡종목심에 대한 선호도가 높을 것으로 판단된다. 본 연구 결과를 통해 세가지 형태의 삼원교잡이 육질에 영향을 미칠 수 있음을 확인하였다.