Increasing thermal conductivity of buffer materials makes the disposal tunnel and hole spacings in high-level radioactive waste (HLW) repositories decrease, so that the area of the HLW repository decreases, which gives more choices to choose the HLW repository site and economical cost savings to construct HLW repositories. Thus, developing enhanced buffer materials with improved thermal conductivity is needed. One of the methods to develop enhanced buffer materials is to add additives to the bentonite which is main material for buffer materials. Most additives have high thermal conductivity, but most additives do not swell or less swell than bentonite, so that the swelling pressure of the enhanced buffer materials by additives decreases compared to the swelling pressure of pure bentonite buffer materials. Swelling pressure is an important performance criterion to design buffer materials. Thus, it is important to confirm the swelling pressure of the enhanced bentonite. However, it is not simple to measure the swelling pressure of the buffer materials and furthermore, it takes several days to measure the swelling pressure of the buffer materials. For these reasons, swelling index can be considered to predict the swelling pressure of the enhanced buffer materials relatively. In this study, it was investigated through tests how the swelling index of bentonite-sand mixtures change according to the amount of sand and it was found that the linear relationship between swelling index and sand amount in the bentonite-sand mixtures.

알코올의 탈수를 위하여 에너지 다소비 공정인 증류 공정을 투과증발 막 공정으로 대체하려는 연구가 많이 진행 되어져 왔다. 대표적인 투과증발 막인 PDMS 분리막에 대한 시간의존적 분리 거동은 분리 메카니즘의 이해에 매우 중요하다. 따라서 본 연구에서는 50 wt% 에탄올-물 혼합용액에 대하여 50°C에서 막면적 1194 cm2인 PDMS/PSF 분리막 모듈의 시간의 존적인 투과증발 분리 거동을 고찰하였다. 총 유속과 에탄올/물 분리계수는 투과증발 시간이 증가함에 따라서 초기에 증가하 다가 다시 감소하였다. 초기 분리성능의 증가는 건조한 PDMS 분리막에 에탄올이 용해되는데 시간이 걸리기 때문이며, 후기 분리성능의 감소는 주입 탱크의 에탄올 농도가 시간에 따라서 감소하기 때문에 나타나는 현상이었다. 따라서 본 연구로부터 PDMS 분리막을 통한 에탄올의 투과는 용해-확산 메카니즘에 의해 발생된다는 것이 재확인되었다.

PURPOSES : This study compared the performance evaluation of a hot mix asphalt (HMA) and asphalt mixture of a warm-antistrip agent. METHODS : A mix design applying Korean standards was conducted to evaluate the performance evaluation. Thereafter, the quality standard evaluation of the asphalt mixture produced was conducted, and if all quality standards were satisfied, a performance evaluation was conducted. Types of performance evaluation included the Hamburg wheel tracking test and dynamic modulus test. RESULTS : As a result of the Hamburg wheel tracking test, the asphalt mixture with a warm-antistrip agent obtained a lower sedimentation value at 10000 times and 20000 times. This result is considered to have higher plastic deformation resistance of the asphalt mixture with a Warm-antistrip agent than HMA. The U.S. Department of Transportation stipulates that plastic deformation resistance is excellent if the asphalt mixture does not exceed 20,000 times the precipitate of 20 mm. Therefore, we confirmed that the plastic deformation resistance of the asphalt mixture with a warm-antistrip agent was excellent. Additionally, the master curve was analyzed by synthesizing the results of the dynamic modulus test. When analyzing the low load cycle at the bottom left of the master curve, the dynamic modulus value of the master curve was higher in the asphalt mixture with a warm-antistrip agent than in the HMA. In addition, when analyzing the high load cycle part, the dynamic modulus of the HMA was measured to be higher than that of the asphalt mixture with a warm-antistrip agent. Accordingly, the resistance to fatigue cracking of the asphalt mixture with a warm-antistrip agent was considered superior to that of the HMA. CONCLUSIONS : As a result, we confirmed that the asphalt mixture with a warm-antistrip agent that satisfies the Korean quality standards had better plastic deformation and fatigue resistance for all performance evaluation tests conducted in this study than the HMA. However, since the Hamburg wheel tracking test did not significantly differ in the amount of sedimentation in the performance evaluation tests and the mixture using one additive was compared with HMA, studies on the effects of various additives containing warm-antistrip agents are required.

PURPOSES : Graphene nanoplates, which have recently been in the spotlight in various fields, are a layer of graphite used in pencil leads, with carbon arranged in hexagonal honeycomb shapes. The graphene is 0.2 nanometers thick, and it possesses high physical and chemical stability, high strength, and conductivity. These graphene nanoplates have been studied for application in various devices such as semiconductors and batteries, and in the construction sector, where they are used as additives to improve the durability of cement concrete. The purpose of this study was to investigate the physical, and functional properties of graphene-modified asphalt mixtures. METHODS : In this study, the graphene input content of asphalt mixture samples was determined using an asphalt performance grade (PG) test. Based on the results of the test, their strength, stiffness, thermal properties, and electrical conductivity were evaluated. Indirect tensile strength test and dynamic modulus (DM) test were conducted to evaluate the strength and stiffness, and thermal conductivity tests and electrical conductivity evaluations were conducted for determining the functionality of the graphene-modified asphalt mixtures. The thermal conduction test was used to measure the external temperature change over time by placing a general heated asphalt mixture and graphene-modified asphalt with the same raw material-specific mixing ratio inside the temperature chamber in order to measure the heat conductivity. The electrical conductivity was evaluated using a digital multimeter to measure the resistance of DC voltage and DC current via a 4-probe method. RESULTS : The performance grade (PG) test results showed that, for a dynamic shear rheometer (DSR), both tests met the baseline and that physical changes in the binder did not appear evident with graphene addition. Furthermore, each content met the baseline for the bending beam rheometer (BBR). The increasing ratio of flexural creep stiffness approached the maximum when 7.5% graphene was used. In indirect tensile strength test, an average of thrice the indirect tensile strength for graphene-modified asphalt was 0.92 N/mm2, which was approximately 0.04 N/mm2 higher than the average measured three times that of hot mix asphalt mixture, with the same raw material mixing ratio. In the thermal conduction tests, the temperature and the rate of change of temperature of the graphene-modified asphalt mixture were higher than those of the hot-mix asphalt mixture. Lastly, the results of the electric conductivity test using the 4-probe method showed that the electrical conductivity increased slightly as the graphene content increased, but overall, it showed very low electrical conductivity. CONCLUSIONS : In this study, the potential for enhancing the physical and functional performance of graphene nanoplates applied to asphalt mixtures was demonstrated. However, it is practically difficult to arrange graphene particles continuously within an asphalt mixture, which is believed to have very low electrical conductivity.

PURPOSES : The purpose of this study was to evaluate the newly developed Guss mastic asphalt mixtures, called EQ-mastic asphalt mixtures, which contain melted additives for decreasing cooking time. METHODS : A series of experiments were performed to investigate the effectiveness of the melted additives in EQ-mastic asphalt mixtures. Both the existing Guss mastic asphalt mixture and the EQ-mastic asphalt mixture were produced with the same amounts of asphalt binders, aggregates, and fillers, but the existing Guss mastic asphalt mixture contained 3% Trinidad lake asphalt (TLA). The EQ-mastic asphalt mixture contained 3% of additives, including TLA and polyolefin. The physical material performances of both mastic asphalt mixtures were obtained by conducting the Luer fluidity test, penetration test, dynamic stability test, and low-temperature bending test. The results of the tests for the existing Guss mastic and EQ-mastic asphalt mixtures were compared. RESULTS : The fluidity, penetration, dynamic stability, and low-temperature bending strains of both the existing Guss mastic and EQmastic asphalt mixtures all satisfied the standard values provided in the production and construction guides of the Guss mastic asphalt pavement. CONCLUSIONS : When melted additives containing polyolefin are used in the production of Guss mastic asphalt mixtures, the cooking time decreases, so that the corresponding energy consumption and asphalt fume amount can be reduced. Therefore, an EQ-mastic asphalt mixture is proposed for use as an eco-friendly pavement material.

본 연구에서는 느타리(Pleurotus ostreatus)와 표고(Lentinula edodes) 버섯차 개발을 위하여 귀리(oat)와 현미(brown rice)를 부재료로 사용함으로서 버섯 특유의 향미를 저감시킴과 동시에 곡물류 특유의 고소함과 영양학적 가치 향상을 기대하였다. 이에 버섯시료의 가공방법 중 열풍건조 및 로스팅 처리에 의한 생리활성 및 영양성 분의 변화를 분석한 결과, 느타리와 표고의 열풍건조 및 로스팅 시료 사이의 DPPH 라디컬 소거능과 아질산염소 거능의 차이는 크게 없었으나, 총 폴리페놀 함량과 베타글루칸 함량은 로스팅 처리에 의하여 함량치가 증가하는 것으로 나타났다. 또한 로스팅 처리된 귀리와 현미의 생리활성과 영양성분을 비교한 결과, 귀리의 DPPH 라디컬 소거능 및 베타글루칸 함량은 현미에 비하여 높은 것으로 나타났으며, 귀리는 높은 글루탐산(Glu) 성분 등을 포함하여 모든 아미노산 성분이 현미보다 높게 나타났다. 로스팅 버섯 시료와 부재료의 혼합비율별 추출온도 및 추출 시간 조건에 따른 생리활성 분석결과, DPPH 라디컬 소거 능은 로스팅 표고와 귀리 1:1 혼합물(LE+O)의 100 ̊C, 3분 추출조건에서 33.5%로 가장 높았으며, 아질산염소거 능은 느타리와 현미 3:1 혼합물(PO+B)의 100 ̊C, 10분 추 출조건에서 49.9%로 가장 높은 소거활성을 보였다. 총 폴리페놀 함량은 70℃의 10분 추출시간 조건에서 느타리와 현미 3:1 혼합추출물(PO+B)의 함량치가 16.2 mg GAE/g 로 가장 높았으며, 베타글루칸 함량은 표고와 현미 (LE+B) 3:1 혼합물에서 34.4%로 다른 혼합비율의 함량치에 비하여 높았다. 아미노산 분석결과, 느타리와 현미 혼 합물(PO+B) 중 1:1 혼합비율에서 필수 아미노산 성분함량이 다른 혼합비율에 비하여 높았으며, 표고와 현미 (LE+B) 혼합물 3:1의 비율에서 필수아미노산 성분 함량이 가장 높았다. 아미노산 성분 중 단맛과 감칠맛을 나타내는 성분함량이 월등히 높았던 귀리를 혼합함에 따른 느타리, 표고와 귀리 혼합물에서의 아미노산 성분함량의 상승효과는 나타나지 않았다.

PURPOSES : The purpose of this study is to analyze the effect of ions in emulsion asphalt on recycling cold asphalt concrete and suggest the possibility of using anionic and nonionic emulsion asphalt. METHODS : In this study, indirect tensile strength, toughness, tensile strength ratio, and dynamic immersion tests were conducted to determine the effects of cation, anion, and non-ion emulsified asphalt on the cold recycled asphalt mixture. Crack resistance was evaluated through indirect tensile strength and toughness tests and the tensile strength ratio and dynamic immersion test were evaluated through tensile strength ratio and dynamic water immersion test. RESULTS : Indirect tensile strength and toughness measurement results demonstrated that the mixture using anion and non-ion emulsified asphalt tended to be higher than that using cation emulsified asphalt; this is due to the high content of reclaimed asphalt pavement with a cationic or ionic surface, which is related to the use of cation-emulsified asphalt in the mixture and has shown a low strength tendency. The tensile strength ratio measurement demonstrated that the mixture using non-ion emulsified asphalt tended to be approximately 15 % higher than that of the anion mixture. This demonstrated that the chemical additive used in the mixture showed a complete hydration reaction with the distribution to the mixture. The dynamic immersion test indicates that the aggregate film rate of asphalt is highly influenced by the surface electric charge of the new aggregate while the ionicity effect appears to be insignificant, at 75 - 85 %, when circular aggregates are used. CONCLUSIONS : High reclaimed asphalt pavement content in cold recycled asphalt mixture, as well as non-ion and anionic emulsified asphalt, is advantageous, reducing cracking and improving moisture resistance. It is believed that anions and non-ions may be better utilized than applying the existing criteria to the cold temperature recycled asphalt mixture with high reclaimed asphalt pavement content. In addition, if the scope of the emulsified asphalt is expanded, various additives can be used, which will require analysis of materials, such as fertilizers and additives.

PURPOSES : The objective of this study is to address various problems, such as an increase in material cost and premature failure (e.g., cracks and potholes) of porous pavements, and to develop multifunctional asphalt and asphalt mixtures to ensure the long-term commonality of porous asphalt pavements. METHODS : A basic quality test of two types of porous asphalt mixtures was performed. One type consisted of the existing porous asphalt mixture, using domestically presented grading, and the other a porous asphalt mixture using high-viscosity modified asphalt with enhanced low-temperature properties, aimed at improving strain resistance and developed by applying the grading suggested by the Federal Highway Administration (FHWA). RESULTS : The cantabros loss rate was 19.62 % for conventional modified asphalt (PG 82-22) and 5.95 % for the developed highviscosity modified asphalt (PG 88-28), indicating that both mixtures passed the criteria. Regarding the drain-down loss rate, mixtures using both types of asphalt were found to pass all quality standards. The average permeability coefficients for each porous asphalt mixture were 0.023 and 0.018 and both types of porous asphalt mixtures satisfied the quality standard of 0.01 cm/s, as given by the Asphalt Concrete Pavement Guidelines of the Ministry of Land, Infrastructure, and Transport. CONCLUSIONS : As a result of the mix design of the two porous asphalt mixtures, the mixture developed in this study was found to be superior to the conventional porous asphalt mixture using conventional porous asphalt grading and modified asphalt.

In this paper, a durability study is presented to enhance the mechanical properties of an Fe-Si-Al powderbased magnetic core, through the addition of graphite. The compressive properties of Fe-Si-Al-graphite powder mixtures are explored using discrete element method (DEM), and a powder compaction experiment is performed under identical conditions to verify the reliability of the DEM analysis. Important parameters for powder compaction of Fe-Si-Algraphite powder mixtures are identified. The compressibility of the powders is observed to increase as the amount of graphite mixture increases and as the size of the graphite powders decreases. In addition, the compaction properties of the Fe-Si-Al-graphite powder mixtures are further explored by analyzing the transmissibility of stress between the top and bottom punches as well as the distribution of the compressive force. The application of graphite powders is confirmed to result in improved stress transmission and compressive force distribution, by 24% and 51%, respectively.

PURPOSES : This study was performed to evaluate the short-term aging (SA) protocols of the normal hot-mix asphalt (HMA) mixture, to explore problems, and to suggest proper procedures based on fundamental principles of SA in terms of the SA temperature (T) and length of time (Lt) in existing specifications in several countries including Korea. METHODS : As the SA in our lab is a simulation of field SA, which is an inevitable procedure occurring naturally in the current field practice, major SA guidelines of foreign countries and Korea were reviewed to investigate problems that showed discrepancies with field practice. The aging quantity (Aq) model was introduced as a function of T and Lt, based on the correlation with absolute viscosity (AV) to estimate Aq by T and Lt. The normal SA (NSA) was suggested through an example procedure inducing binder aging level similar to the RTFOtreated binder AV or Aq. Based on the NSA Aq level, lower, proper, or higher SA conditions were discovered from the existing SA guidelines. RESULTS : As Aq has excellent correlation with AV, the proper T and Lt for NSA as an example was suggested based on the AV of RTFOtreated binder to induce an Aq range of 19,000-25,000 min.℃. It was found that there were several problems in the existing guidelines in USA and Korea. These included lower T, shorter or longer Lt, and air blowing or stirring the mix during SA, which were not matched with the practical condition of loaded HMA mixtures that were short-term aged under hot temperatures in trucks. CONCLUSIONS : It was concluded that there are several problems in the current SA guidelines, which do not provide proper HMA temperature to mixtures for proper (modal) length of time. Therefore, these guidelines should be reevaluated carefully and revised based on the fundamental field SA principle. The NSA condition should be suggested using proper HMA T and modal Lt for better simulation of field SA practice.

Growth factors and cytokines play an important role in delaying skin aging. However, there has been no animal stability test reported for them yet. In the present study, we examined the plausibility of Growth factor and Cytokine Mixtures (GCM) as a cosmetic ingredient by assessing skin irritation and ocular irritation for hypersensitivity using New Zealand white rabbits. Skin safety study was performed to evaluate the potential toxicity of GCM based on the irritation test. For the irritation test, GCM was applied to the rabbit skin, and no adverse reaction, such as erythema and edema, had been observed from the exposed skin sites. In the ocular irritation test, the treatment of GCM did not cause any adverse reaction on rabbit eyes, including cornea, iris, and conjunctiva tissues. From the results, both tests proved that GCM makes no irritable reaction on skin and eye mucous membrane of rabbit. Hence, it may be suggested that GCM can be safely applied as a cosmeceutical ingredient without causing any significant hypersensitivity reaction.

The hydrogen reduction behavior of the CuO-Co3O4 powder mixture for the synthesis of the homogeneous Cu-15at%Co composite powder has been investigated. The composite powder is prepared by ball milling the oxide powders, followed by a hydrogen reduction process. The reduction behavior of the ball-milled powder mixture is analyzed by X-ray diffraction (XRD) and temperature-programmed reduction at different heating rates in an Ar-10%H2 atmosphere. The scanning electron microscopy and XRD results reveal that the hydrogen-reduced powder mixture is composed of fine agglomerates of nanosized Cu and Co particles. The hydrogen reduction kinetics is studied by determining the degree of peak shift as a function of the heating rate. The activation energies for the reduction of the oxide powders estimated from the slopes of the Kissinger plots are 58.1 kJ/mol and 65.8 kJ/mol, depending on the reduction reaction: CuO to Cu and Co3O4 to Co, respectively. The measured temperature and activation energy for the reduction of Co3O4 are explained on the basis of the effect of pre-reduced Cu particles.

A powder mixture of 70 wt% Al2O3 and 30 wt% hydroxyapatite (HA) is sintered at 1300 ℃ or 1350 ℃ for 2 h at normal pressure. An MgF2-added composition to make HA into fluorapatite (FA) is also prepared for comparison. The samples without MgF2 show α & β-tricalcium phosphates (TCPs) and Al2O3 phases with no HA at either of the sintering temperatures. In the case of 1,350 ℃, a CaAl4O7 phase is also found. Densification values are 69 and 78 %, and strengths are 156 and 104MPa for 1,300 and 1,350 ℃, respectively. Because the decomposition of HA produces a H2O vapor, fewer large pores of 5-6 μm form at 1,300 ℃. The MgF2-added samples show FA and Al2O3 phases with no TCP. Densification values are 79 and 87%, and strengths are 104 and 143 MPa for 1,300 and 1,350 ℃, respectively. No large pores are observed, and the grain size of FA (1-2 μm) is bigger than that of TCP (0.7 μm ≥) in the samples without MgF2. The resulting TCP/Al2O3 and FA/Al2O3 composites fabricated in situ exhibit strengths 6-10 times higher than monolithic TCP and HA.

(주)파인텍에서 개발한 제올라이트 4A 분리막을 이용하여 물/알코올의 단일및 혼합성분의 투과증발 실험을 수행하였다. 다양한 온도 및 농도 조건 실험을 통해 물/메탄올(분리계수 250 이상) 물/에탄올(3,000 이상), 물/이소프로필알코올(1,500 이상), 물/부탄올 (1,500 이상) 혼합물로 부터 물을 선택적으로 분리할 수 있음을 확인하였다. 활동도계수-퓨개시티 모형, GMS 모형 및 Dusty Gas 모형을 이용하여 단일성분 및 혼합물의 투과증발 거동을 모사하였으며, GA (Genetic Algorithm) 및 SQP (sequential quadratic programming)를 이용한 상수추정을 통하여 제올라이트 활성층의 흡착 및 확산 상수를 구하였다.

W-10 wt% Ti alloys that have a homogeneous microstructure are prepared by thermal decomposition of WO3-TiH2 powder mixtures and spark plasma sintering. The reduction and dehydrogenation behavior of WO3 and TiH2 are analyzed by temperature programmed reduction and a thermogravimetric method, respectively. The X-ray diffraction analysis of the powder mixture, heat-treated in an argon atmosphere, shows W- oxides and TiO2 peaks. Conversely, the powder mixtures heated in a hydrogen atmosphere are composed of W, WO2 and TiO2 phases at 600 ℃ and W and W-rich β phases at 800 ℃. The densified specimen by spark plasma sintering at 1500 ℃ in a vacuum using hydrogen-reduced WO3-TiH2 powder mixtures shows a Vickers hardness value of 4.6 GPa and a homogeneous microstructure with pure W, β and Ti phases. The phase evolution dependent on the atmosphere and temperature is explained by the thermal decomposition and reaction behavior of WO3 and TiH2.

The hydrogen reduction behavior of MoO3-CuO powder mixture for the synthesis of homogeneous Mo-20 wt% Cu composite powder is investigated. The reduction behavior of ball-milled powder mixture is analyzed by XRD and temperature programmed reduction method at various heating rates in Ar-10% H2 atmosphere. The XRD analysis of the heat-treated powder at 300oC shows Cu, MoO3, and Cu2MoO5 phases. In contrast, the powder mixture heated at 400oC is composed of Cu and MoO2 phases. The hydrogen reduction kinetic is evaluated by the amount of peak shift with heating rates. The activation energies for the reduction, estimated by the slope of the Kissinger plot, are measured as 112.2 kJ/mol and 65.2 kJ/mol, depending on the reduction steps from CuO to Cu and from MoO3 to MoO2, respectively. The measured activation energy for the reduction of MoO3 is explained by the effect of pre-reduced Cu particles. The powder mixture, hydrogen-reduced at 700oC, shows the dispersion of nano-sized Cu agglomerates on the surface of Mo powders.