The optimization of brown rice replacement ratio and superheated steam (SHS) treatment conditions in production of extruded rice snack for infants were conducted using a response surface methodology. Experiments were designed using a Box-Behnken design with three independent variables (brown rice replacement ratio, SHS temperature, and SHS time) and two response variables (hardness and water uptake). The second order polynomial model showed a satisfactory description of the experimental results. Optimal conditions for extruded snack with the lowest predicted hardness (2.84 kg/cm2) were 15.81% of brown rice replacement with SHS treatment at 279.59oC for 197.40 sec. Meanwhile, optimal conditions for extruded snack with the highest predicted water uptake (384.79%) were 17.18% of brown rice replacement ratio with SHS treatment at 274.52oC for 196.22 sec.

터널은 토공부와 비교하면 어둡고 갇힌 공간이기 때문에 콘크리트 포장 시공시 품질관리가 어려워 교 통 개방 후 승차감이 불량하거나 심각한 소음 문제가 발생한다. 일반적으로 토공부의 노후 콘크리트 포장 에서는 주행 쾌적성 문제를 해결하기 위해 다이아몬드 그라인딩 공법(DG)을 적용하여왔다. 하지만 돌출 된 fin이 깨지거나 마모가 되면 그 기능이 다하여 재시공이 필요한 문제가 있다. 이러한 문제점을 해결하 기 위해 개발된 공법이 NGCS (Next Generation Concrete Surface)이다. 본 연구에서는 토공부 콘크리 트 포장에 적용된 NGCS 공법을 터널 내 포장에 적용하여 도로 이용자의 주행 쾌적성을 향상을 위한 노력 을 진행하였다. 일반 종방향 타이닝, DG 및 NGCS을 건설중인 터널에 적용한 후 공용성을 평가하였다. 공용성 평가결과, 평탄성에서는 NGCS 공법과 DG 우수하였으며, 종방향 타이닝이 가장 낮았다. 미끄럼 마찰 저항에서는 DG가 가장 높았고, 다음으로 NGCS 및 종방향 타이닝 순으로 평가되었다. 실내외 소음 평가 결과, NGCS 구간의 소음도가 가장 낮았으며, 다음으로 DG, 종방향 타이닝 순이었다. 전체적인 평 가 결과, 고기능성 표면처리 공법인 NGCS를 터널 내 콘크리트 포장에 적용한다면 주행 안전성을 높이고 소음을 감소시켜 쾌적한 주행환경을 구현할 수 있을 것이다.

Perfluorinated sulfonic acid (PFSA) ionomers have been widely used as membranes in the fields of green power generation and electrolysis. In spite of their high ion-conducting properties, it is difficult to apply them in the freestanding membrane state to harsh operation conditions owing to their chemical and electrochemical degradation issues. A promising membrane concept to satisfy this purpose would be “pore-filling membrane” composed of PFSA ionomers and porous PTFE support films. In this study, the porous PTFE support film treated with a cheap hydrophilic polymer is used as a reinforced material. Interestingly, the resulting PFSA-PTFE pore-filling membranes exhibit an extremely high proton conductivity with a fairly reduced ionomer content, which may give a valuable information to design a desirable pore-filling membrane.

Response surface methodology (RSM) based on a Box-Behnken Design (BBD) was applied to optimize the thermal-alkaline pre-treatment operating conditions for anaerobic digestion of flotation scum in food waste leachate. Three independent variables such as thermal temperature, NaOH concentration and reaction time were evaluated. The maximum methane production of 369.2 mL CH4/g VS was estimated under the optimum conditions at 62.0°C, 10.1% NaOH and 35.4 min reaction time. A confirmation test of the predicted optimum conditions verified the validity of the BBD with RSM. The analysis of variance indicated that methane production was more sensitive to both NaOH concentration and thermal temperature than reaction time. Thermal-alkaline pretreatment enhanced the improvement of 40% in methane production compared to the control experiment due to the effective hydrolysis and/or solubilization of organic matters. The fractions with molecular weight cut-off of scum in food waste leachate were conducted before and after pre-treatment to estimate the behaviors of organic matters. The experiment results found that thermal-alkaline pre-treatment could reduce the organic matters more than 10kD with increase the organic matters less than 1kD.

PURPOSES : The objective of this study is to evaluate the performance properties of chip seals and fog seals with polymer-modified emulsions. METHODS : The performance of chip seals and fog seals was evaluated on the basis of common issues in surface treatments. Granite aggregate and four types of asphalt emulsions (one of the unmodified and three of the modified emulsions) were used considering the usage in field. A Vialit test was performed to determine the aggregate retention, and the MMLS3 (Third Scale Model Mobile Load Simulator) test was conducted to determine the aggregate retention, bleeding, and rutting. In addition, the fog seal specimens were tested by the BPT (British Pendulum Test) to evaluate skid resistance. RESULTS AND CONCLUSIONS : Overall, the polymer-modified emulsions (PMEs) showed better aggregate retention and bleeding resistance for both chip seals and fog seals. When comparing the performance of the PMEs, the difference was not considerable. In addition, PMEs present significantly better rutting resistance than unmodified emulsions. For skid resistance, if the recommended mix design is applied, the specimens do not cause issues with skid resistance. Although all of the fog seal specimens were over the criteria for skid resistance, the specimen fabricated by the high emulsion application rate (EAR) of the unmodified emulsion was nearly equivalent to the skid value criteria. Therefore, the use of an unmodified emulsion with a high EAR should be carefully applied in the field.

Physical and chemical changes in a polished wafer and in 2.5μm & 4μm epitaxially grown Si layer wafers (Epilayer wafer) after surface treatment were investigated. We characterized the influence of surface treatment on wafer properties such as surface roughness and the chemical composition and bonds. After each surface treatment, the physical change of the wafer surface was evaluated by atomic force microscopy to confirm the surface morphology and roughness. In addition, chemical changes in the wafer surface were studied by X-ray photoemission spectroscopy measurement. Changes in the chemical composition were confirmed before and after the surface treatment. By combined analysis of the physical and chemical changes, we found that diluted hydrofluoric acid treatment is more effective than buffered oxide etching for SiO2 removal in both polished and Epi-Layer wafers; however, the etch rate and the surface roughness in the given treatment are different among the polished 2.5μm and 4μm Epi-layer wafers in spite of the identical bulk structural properties of these wafers. This study therefore suggests that independent surface treatment optimization is required for each wafer type, 2.5μm and 4μm, due to the meaningful differences in the initial surface chemical and physical properties.

PURPOSES : The objective of this study is to evaluate the curing and adhesive behavior of asphalt emulsions including polymer-modified emulsions for chip seals and fog seals. METHODS : For the laboratory testing, the evaporation test, the bitumen bond strength (BBS) test, and the Vialit test are used. Also, the rolling ball test and the damping test are employed to evaluate the curing properties of the fog seal emulsions. In order to conduct all the tests in controled condition, all test procedures are performed in the environmental chamber. The CRS-2L and the SBS CRS-2P emulsions are used as a polymer-modified emulsion, and then unmodified emulsion, the CRS-2, is compared for the evaluation of chip seal performance. For the fog seal performance evaluation, two types of polymer-modified emulsions (FPME-1 and FPME-2) and one of unmodified emulsion, the CSS-1H, are employed. All the tests are performed at different curing times and temperatures. RESULTS AND CONCLUSIONS : Overall, PMEs show better curing and adhesive behavior than non-PMEs regardless of treatments types. Especially, the curing and adhesive behavior of PMEs is much better than non-PMEs before 120 minutes of curing time. Since all the test results indicate that after 120 minutes of curing time the curing adhesive behavior of emulsions, the early curing time, i.e., 120 minutes, plays an important role in the performance of chip seals and fog seals.

PURPOSES : The purpose of this article is to compare and evaluate the riding comfort of a passenger in tunnels depending on different surface textures of concrete pavement. METHODS: Evaluation of riding comfort is conducted at 17 sections, which have different surface texture such as transverse tinned(TT), longitudinal tinned(LT) and diamond grinded(DG). A triaxial accelerometer was set up on the passenger seat surface of the test vehicle to measure vibrations of an occupant, then the effects of vibration on comfort and health were evaluated by ISO 2631. And microphones were installed at passenger's ears height to measure sound pressure level(SPL) in the test vehicle. Additionally, a surface microphone was installed on the inside of wheel arch to evaluate noise between tire and pavement by NCPX method. All tests were conducted cruising at 100km/h. RESULTS : The results of all tests are as follows. First, both vibration magnitudes for comfort and for health in LT and DG sections are almost same and they represent lower than those in TT sections. Second, the average SPL of DG shows the lowest decibels among them. And third, it is founded that interior noise is significantly affected by noise between tire and pavement. CONCLUSIONS : It may be concluded that DG can provide more excellent riding comfort to passenger than LT or TT. Therefore, it is necessary to consider applying DG to existing pavement surface to improve surface condition when the driving environment especially requires riding comfort like a long tunnel.

PURPOSES : The objective of this study is to evaluate the bond strength of asphalt emulsions including polymer-modified emulsions for chip seals and fog seals using the bitumen bond strength (BBS) test. METHODS : For the laboratory testing, the Pneumatic Adhesion tensile Testing Instrument(PATTI) device is used to measure the bond strength between the asphalt emulsion and aggregate substrate based on the AASHTO TP-91. In order to conduct all the tests in controled condition, all test procedures are performed in the environmental chamber. The CRS-2L and the SBS CRS-2P emulsions are used as a polymermodified emulsion, and then unmodified emulsion, the CRS-2, is compared for the evaluation of chip seal performance. For the fog seal performance evaluation, two types of polymer-modified emulsions and one of unmodified emulsion, the CSS-1H, are employed. For chip seal study, the BBS tests are performed at 30, 60, 120, and 240 minutes of curing times with curing and testing temperatures of 15℃, 25℃, and 35℃. The fog seal tests are conducted at 30, 60, 90, 120, 180 minutes, and 24 hours with curing and testing temperatures of 25℃, 30℃, and 35℃. RESULTS AND CONCLUSIONS : Overall, chip seal emulsions and fog seal emulsions show the similar bond strength trend. At the same testing condition, polymer-modified emulsions show better bond strength than unmodified emulsions. Also, there is no significant difference between polymer-modified emulsions. One of important findings is that the most bond strength reaches their final bond strength within one hour of curing time. Therefore, the early curing time plays a vital role in the performance of chip seals and fog seals.

PURPOSES: Surface treatment is a favorable method in the pavement preventive maintenance. This study (Part Ⅰ) aimed to develop the low viscosity filling material for waterproof characteristics and high penetrable and weather resistance, and a series of companion study (Part Ⅱ) presents the coating characteristics and performance analysis using field and lab tests. METHODS : Hydrophobic characteristics of the advanced surface treatment material are observed and measured the filling depth and the permeability for sand and asphalt pavement specimen using the water absorption test and permeability test, X-RAY CT test. Color difference for the weather resistance using ultraviolet ray accelerated weathering test is compared with asphalt pavement specimens. RESULTS : The developed material shows the decreased water absorption and increased impermeable effect because of the hydrophobic characteristics. It is found that the filling depth is about 6mm and weather resistance is better than asphalt pavement specimen. CONCLUSIONS: The advanced hydrophobic - low viscosity filling treatment material is developed in this study (Part Ⅰ) to improve the waterproof characteristics and high filling capacity and weather resistance for the pavement preventive maintenance.

The effects of printed circuit board electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the electromigration reliability and shear strength of Sn-3.5Ag Pb-free solder bump were systematically investigated. In-situ annealing tests were performed in a scanning electron microscope chamber at 130, 150, and 170˚C in order to investigate the growth kinetics of intermetallic compound (IMC). Electromigration lifetime and failure modes were investigated at 150˚C and 1.5×105A/cm2, while ball shear tests and failure mode analysis were conducted under the high-speed conditions from 10 mm/s to 3000 mm/s. The activation energy of ENIG and OSP surface finishes during annealing were evaluated as 0.84 eV and 0.94 eV, respectively. The solder bumps with ENIG surface finish showed longer electromigration lifetime than OSP surface finish. Shear strengths between ENIG and OSP were similar, and the shear energies decreased with increasing shear speed. Failure analysis showed that electrical and mechanical reliabilities were very closely related to the interfacial IMC stabilities.

PURPOSES : Surface treatment material for pavement preventive maintenance should be inspected field applicability. This study(Part Ⅱ) aimed to checkup coating characteristics and performance analysis using lab and field tests. The hydrophobic - low viscosity filling material for pavement preventive maintenance is presented in Part Ⅰ, which is a series of companion study. METHODS: Relative comparison between general asphalt mixtures and surface treatment asphalt mixtures are analyzed and measured for the field application such as indirect tensile strength ratio(TSR), abrasion resistance, crack propagation resistance, temperature resistance, coating thickness, permeability resistance and skid resistance in terms of british pendulum number(BPN). RESULTS: It is found that TSR, crack propagation resistance and permeability resistance is increased as against uncoated asphalt specimen. Abrasion resistance and temperature resistance is secured from the initial coating thickness point of view, which is about 0.2~0.3mm. Skid resistance on the surface treatment pavement is satisfied with the BPN criteria of national highway because of exposed aggregate and crack sill induced pavement deterioration and damage cracks. CONCLUSIONS : The hydrophobic - low viscosity surface treatment material for pavement preventive maintenance is validated on field applicability evaluation based on quantitative analysis of coating thickness and performance analysis using lab and field tests.

목적: 공기 중에서 플라즈마 처리가 된 상용 불화규소 아크릴레이트 RGP 콘택트렌즈(Boston XO)의 분위기와 유지 시간에 따른 표면 성분 및 습윤성의 변화를 연구하였다. 방 법: 렌즈는 진공, 공기, 물 등의 분위기로 보관했으며, X-선광전자분광분석기(XPS)로 성분과 화학결합을, 접촉각으로 습윤성의 변화를 측정하여 평가하였다. 결과: RGP 콘택트렌즈에 플라즈마 처리를 하면 렌즈 표면에 친수성기(C-O, O-C=O, Si-O)의 증가로 물에 대한 접촉각이 감소하여 표면의 습윤성이 증진되었으나, 모든 분위기에서 시간이 경과함에 따라 친수 성기가 감소하면서 접촉각이 증가하였다. 물 분위기에서는 렌즈 표면에 탄소 및 실리콘과 결합한 산소가 급격히 감소하면서 접촉각이 다시 증가하였다. 결론: 플라즈마 처리된 RGP 콘택트렌즈의 표면이 수분과 접촉하면, 산소가 급격히 감소하고 습윤성이 저하된다.

목적: 플라즈마 표면처리가 불화규소 아크릴레이트 재질의 RGP 콘택트렌즈의 물리화학적 특성에 미치는 영향을 분석하였다. 방법: RGP 렌즈 표면의 플라즈마 처리는 공기 중 상온에서 200 W로 수행하였으며, 처리시간은 0∼250초로 다르게 하였다. 습윤성을 평가하기 위해 접촉각을 측정하였다. 표면 성분은 X-선광전자분광분석기(XPS)로 관찰하고, 플라즈마 처리에 의한 실리케이트의 형성을 분석하였다. 표면의 형상과 거칠기는 원자현미경(AFM)으로 관찰하였다. 산소침투성의 변화는 전기분해 분석법으로 얻은 렌즈의 투과 전류값과 중심두께를 측정하여 비교하였다. 결과: 플라즈마로 표면 처리되면 초기에 접촉각이 급격히 감소하였으며, 처리되지 않은 표면에 비해 30%까지 감소하였다. 표면 성분의 탄소와 불소는 70% 이하로 감소했으나, 산소와 실리콘은 150% 이상 증가하였다. 표면에서 탄소가 감소하는 형태는 접촉각의 변화와 직접적으로 관계가 있었다. 플라즈마 표면처리에 의해 표면의 탄소와 불소는 휘발하고, 유리된 실리콘이 산소와 결합하여 표면에 친수성 실리케이트(SiOx, x=1.5∼2.0)가 형성되며, 실리케이트는 50% 이상 크게 증가하였다. 플라즈마 처리된 표면에서 원형이나 직각형의 돌출부가 관찰되고, 거칠기(RMS)는 40% 이상 증가하였다. 결론: RGP 콘택트렌즈를 공기 중에서 플라즈마 처리하면 표면에 친수성인 실리케이트가 형성되어 습윤성은 개선되지만 산소침투성에는 영향을 주지 않았다. 습윤성의 증가는 표면형상의 변화보다는 실리케이트의 형성이 더 큰 영향을 준 것으로 판단되었다. 또한 플라즈마 처리에 의해 표면에 국한되어 형성된 실리케이트가 열린 구조를 갖고 있어 산소침투성에 유의한 변화가 없었던 것으로 생각된다.

Recently, consumption of magnesium alloys has increased especially in the 3C (computer, communication, camera) and automobile industries. The structural application of magnesium alloys has many advantages due to their low densities, high specific strength, excellent damping and anti-eletromagnetic properties, and easy recycling. However, practical application of these alloys has been limited to narrow uses of mild condition, because they are inferior in corrosion resistance and wear resistance due to their high chemical reactivity and low hardness. Various wet and dry processes are being used or are under development to enhance alloy surface properties. Various conversion coating and anodizing methods have been developed in a view of eco-friendly concept. The conventional technologies, such as diffusion coating, sol-gel coating, hydrothermal treatment, and organic coating, are expected to be newly applicable to magnesium alloys. Surface treatments for metallic luster or coloring are suggested using the control of the micro roughness. This report reviews the recent R&D trends and achievements in surface treatment technologies for magnesium alloys.

목적: RGP 콘택트렌즈의 습윤성을 향상시키기 위한 플라즈마 처리의 효과가 얼마나 지속되는지 알아 보고, 렌즈를 착용했을 때 임상적인 성능을 평가하고자 하였다. 방법: 플라즈마 처리된 RGP 콘택트렌즈와 일반 RGP 콘택트렌즈를 세척하기 전과 6회 세척하는 동안 접촉각을 측정하였다. 세척할 때마다 자연건조 후 Sessile drop 방식으로 접촉각을 측정하였다. 세척제는 연마재가 첨가된 것과 연마재가 첨가되지 않은 것을 사용하였다. 대상자의 우안과 좌안에 무작위로 플라즈마 처리 RGP 콘택트렌즈와 일반 RGP 콘택트렌즈를 착용시켰다. 렌즈를 착용하고 있을 때 표면의 습윤성을 평 가하기 위해 렌즈 전면의 NIBUT와 NIDUT를 검사하였다. 결과: 플라즈마 처리된 RGP 콘택트렌즈는 일반 RGP 콘택트렌즈보다 초기 습윤성이 높았지만 세척 후 접촉각이 점차 증가되었다. 연마재가 첨가된 세척액을 사용하여 4회 세척했을 때와 연마재가 첨가되지 않은 세척액을 사용하여 6회 세척했을 때 일반 RGP 콘택트렌즈와 접촉각의 차이가 없었다. 렌즈 전면의 NIBUT 와 NIDUT는 착용1일째 플라즈마처리RGP 콘택트렌즈가일반 RGP 콘택트렌즈보다 더 높았으나 착용7일째에는 유의한 차이가 없었다. 결론: 플라즈마 처리 효과는 최대 1주일 정도 지속되고 초기 착용감을 향상시켜서 적응에 도움을 주는 것으로 판단된다.

현재 지구온난화 등의 환경문제로 인해 각종 산업분야에서 정량화에 대한 요구가 증대되어 해양산업에도 그 수요가 증가하고 있는 실정이다. 따라서 본 연구에서는 차세대 경량화 재료인 마그네슘이 활용되기 위해서 반드시 극복해야할 가장 중요한 특성인 내식특성에 대하여 고찰하고, 그 내식특성 향상을 위한 마그네슘 박막의 Morphology나 결정배향성의 영향을 해명하고자 하였다. 실험결과로부터 제작한 Mg 박막의 전기화학적 내식특성은 Ar 가스압이 높은 조건에서 제작한 막일수록 내식특성이 우수하였다. 이러한 경향은 표면 및 단면의 Morphology와 결정배향성과의 상관관계를 통하여 설명 가능하였다.

Low temperature degradation behavior in yttria stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics was microscopically observed from the phase contrast between monoclinic surface and tetragonal matrix. The degradation behavior was dependent on the surface treatment of sintered Y-TZP, even if the sintering history is same. In the mirror polished specimen, the monoclinic layer appeared in a uniform thickness from the surface. On the contrary, for the specimen with coarse scratch, the thickness of degraded surface was more than double especially from the coarse scratch. Since the scratch results in local deformation, the residual stress should be induced around the scratch. With the transformation from tetragonal to monoclinic, the volume expansion exerts a stress on a neighboring grains and promotes a successive phase transformation. Such a autocatalytic effect can be triggered from the part of coarse scratch.