Evaluation of low temperature performance of asphalt mixture is significant not only for mitigating transverse thermal cracking but also for preventing potential traffic accidents. In addition, the engineers in pavement agency need to inform the proper pavement section where urgent management is needed. Since early 2000, Korea Expressway Corporation Research Division (KECRD) developed an 3D Pavement condition Monitoring profiler vehicle (3DPM) to survey expressway pavement surface condition precisely. The management of whole expressway network became more precise, effective and efficient than before due to application of 3DPM and HPMS. One thing recommended is: performing extensive mechanical test and corresponding data analysis work procedure to further strengthen the feasibility of current 3DPM approach and HPMS. In this paper two activities were considered: first, the pavement section where the urgent care is recommended is selected by means of 3DPM approach. Then asphalt mixture cores were acquired on that specified section then low temperature fracture test: Semi Circular Bending (SCB) test, was performed. The mechanical parameters, energy release rate and fracture toughness were computed then compared. It is concluded that the current 3DPM approach in KEC can successfully evaluate and analyze selected pavement condition. However, more extensive experimental works are needed to further strengthen the current pavement analyzing approaches.

In this study, surface roughness and interfacial defect characteristics were analyzed after forming a high-k oxide film on the surface of a prime wafer and a test wafer, to study the possibility of improving the quality of the test wafer. As a result of checking the roughness, the deviation in the test after raising the oxide film was 0.1 nm, which was twice as large as that of the Prime. As a result of current-voltage analysis, Prime after PMA was 1.07 × 10 A/cm2 and Test was 5.61 × 10 A/cm2, which was about 5 times lower than Prime. As a result of analyzing the defects inside the oxide film using the capacitancevoltage characteristic, before PMA Prime showed a higher electrical defect of 0.85 × 1012 cm2 in slow state density and 0.41 × 1013 cm2 in fixed oxide charge. However, after PMA, it was confirmed that Prime had a lower defect of 4.79 × 1011 cm2 in slow state density and 1.33 × 1012 cm2 in fixed oxide charge. The above results confirm the difference in surface roughness and defects between the Test and Prime wafer.

PURPOSES : This study investigates the abrasion characteristics of coarse aggregate using the Los Angeles (L.A.) abrasion test and the accelerated polishing machine (APM) test. The coarse aggregates are randomly exposed on the surface of asphalt concrete pavements and on exposed aggregate concrete pavements. The exposed aggregates play a very important role in providing skid resistance. Therefore, the adequate abrasion resistance of coarse aggregate must be ensured to maintain the skid resistance during service life. In Korea, the LA abrasion test is conducted according to the KS F 2508 standard for the evaluation of the abrasion resistance of coarse aggregate. However, the road surface abrasion is caused by the friction between the tire and the road surface structure; hence, whether the LA abrasion test, which evaluates the abrasion caused by the impact of coarse aggregates and steel balls, can evaluate the road surface abrasion is questionable. A comparison and an analysis between the APM and LA abrasion tests were conducted herein to evaluate the road abrasion. An analysis was also performed to analyze whether the abrasion characteristics appeared depending on the type of coarse aggregate. METHODS: The results of the APM and LA abrasion tests for various aggregate types were obtained through a series of experiments and literature reviews. The correlation between the LA abrasion loss and the PV data was derived. In addition, the influence of the aggregate type on the abrasion resistance was investigated. RESULTS : An abrasion resistance database was established, and the relationship between the rock types and the abrasion resistance was statistically determined. The results showed that the PV was increased to 0.54 along with a 1% increasing rate of the LA abrasion loss with a 0.67 coefficient of determination. The abrasion resistance was also influenced by the aggregate type, which was found to be statistically significant. CONCLUSIONS: A good relationship between the PV and the LA abrasion loss was obtained, allowing the use of the LA abrasion test (KS F 2508) alone, to reasonably evaluate the abrasion resistance of the exposed aggregate texture. The aggregate types were also found to have an impact on the abrasion resistance.

In a solar coronagraph, the most important component is an occulter to block the direct light from the disk of the sun. Because the intensity of the solar outer corona is 10−6 to 10−10 times of that of the solar disk (I⊙), it is necessary to minimize scattering at the optical elements and diffraction at the occulter. Using a Fourier optic simulation and a stray light test, we investigated the performance of a compact coronagraph that uses an external truncated-cone occulter without an internal occulter and Lyot stop. In the simulation, the diffracted light was minimized to the order of 7.6 × 10−10 I⊙ when the cone angle c was about 0.39◦. The performance of the cone occulter was then tested by experiment. The level of the diffracted light reached the order of 6 × 10−9 I⊙ at c = 0.40◦. This is sufficient to observe the outer corona without additional optical elements such as a Lyot stop or inner occulter. We also found the manufacturing tolerance of the cone angle to be 0.05◦, the lateral alignment tolerance was 45 μm, and the angular alignment tolerance was 0.043◦. Our results suggest that the physical size of coronagraphs can be shortened significantly by using a cone occulter.

현재 살균소독제의 국가 공인시험법은 시험관 내에서 행하는 현탁액시험법으로 실제 현장의 표면 살균을 정확히 평가하기에는 무리가 있다. 본 연구는 국제적으로 표준화 되어 있는 3가지 정량적 표면시험법간의 유효성 평가력 비교를 목적으로 E. coli와 S. aureus를 대상으로 시중 유통되는 대표적 5개 계열 살균소독제의 유효성을 평가하였다. 그 결과 E. coli와 S. aureus에 대한 각 방법별 살균소독력은 ASTM(1)법에서 5.18 ± 0.03, 5.27 ± 0.04 log cfu/carrier, ASTM (2)법에서 4.63 ± 0.04, 3.97 ± 0.03 log cfu/carrier, CEN EN 13697법의 청정조건(CEN(1))에서 6.14 ± 0.05, 5.31 ± 0.10 log cfu/carrier, 오염조건(CEN(2))에서 4.37 ± 0.02, 4.06 ± 0.01 log cfu/carrier로 나타났다. CEN(1)시험법이 ASTM(2)와 CEN(2) 시험법에 비해 살균소독력이 유의적으로 높게 평가되었다. 적용된 3개의 시험법 중 유리를 담체로 사용 한 ASTM(1)법에 비해 스테인리스 스틸을 사용한 ASTM(2) 와 CEN법 적용 시 살균소독효과가 낮게 평가되었다. 결론적으로 3 가지 국가 공인시험법간 유효성 평가결과가 달랐으며, 실제 식품제조 현장에서 사용되는 표면에서의 살균 소독력을 정확히 평가하기 어렵다는 것을 확인할 수 있었다.

현재 미국 및 유럽에서 공정시험법중 하나로 인정되고 있는 표면시험법을 사용하여 유기물과 함께 또는 유기물없이 세균만 건조된 식품접촉 표면에 서의 살균소독제 유효성에 대한 정보를 제공하고자 식품접촉표면으로 사용되는 스테인리스, 폴리프로필렌 및 실리콘에 Escherochia coli ATCC 10536 또는 Staphylococcus aureus ATCC 6538을 접종하고 살균소독제로서 염화벤잘코늄, 차아염소산나트륨 또는 에탄올을 20 ℃에서 5분간 처리하였다. 그 결과, 각 표면의 종류는 살균소독제의 유효성에 큰 영향을 미치지 않았으며, 200 ppm 농도의 염화벤잘코늄 및 차아염소산나트륨은 유기물질이 존재할 경우 생균수를 4 cfu log10/carrier 이상 감소시키지 못하였으나, 40% 에탄올은 생균수를 4 cfu log10/carrier 이상 감소시키는 것으로 나타났다.

To validate the previous conceptual design of cover system, construction of the engineered barrier test facility is completed and the performance tests of the disposal cover system are conducted. The disposal test facility is composed of the multi-purpose working space, the six test cells and the disposal information space for the PR center. The dedicated detection system measures the water content, the temperature, the matric potential of each cover layer and the accumulated water volume of lateral drainage. Short-term experiments on the disposal cover layer using the artificial rainfall system are implemented. The sand drainage layer shows the satisfactory performance as intended in the design stage. The artificial rainfall does not affect the temperature of cover layers. It is investigated that high water infiltration of the artificial rainfall changes the matric potential in each cover layer. This facility is expected to increase the public information about the national radioactive waste disposal program and the effort for the safety of the planned disposal facility.

As a result of abrasion resistance test of decoration wood-based flooring board laminated with PVC on plywood, compared to the flooring board laminated with general HPL surface decoration materials, it was available to secure far higher abrasion resistance. It seems to contribute to secure initial durability and maintenance of decoration wood-based flooring board as an important means, and it might be available for saving repair and maintenance costs due to flooring board issues.

본 연구에서는 유황을 폴리머화하여 내화학성능이 요구되는 구조물의 콘크리트 표면보호재로 활용할 수 있도록 성능을 검토하였다.평가 결과, 유황폴리머 표면도포재의 중력식 스프레이가 적절한 것으로 나타났으며, 도포횟수는 왕복 3회 이상 도포했을 때 1MPa 이상의 부착강도 확보가 가능하였다. 표면보호재가 도포될 콘크리트 표면조건은 상온조건 (20~30℃) 이상에서 높은 부착강도를 나타내었으며,온도가 높을수록 부착강도가 증가하였다. 표면보호재의 채움재 혼입량에 따른 강도특성 평가결과, 20~40% 정도 혼입된 채움재는 유황폴리머의 수축을 저감시키는 효과를 나타내어 강도 향상에 기여하였다. 또한, 플라이애시 보다는 규사 혼입시 부착강도가 높았고, 동시 혼입시가장 우수한 부착강도 특성을 나타내었다. 화학저항성은 플라이애시 및 규사를 각각 20% 대체한 배합에서 부착강도 저하가 최소로 되어우수한 내화학성을 나타내었다. 염소이온 침투에 대한 성능평가를 수행한 결과, 표면보호재를 도포하지 않은 시험체에 비하여 유황폴리머표면보호재를 도포한 경우, 29~48% 정도 염소이온침투저항성이 증대되었다. 표면보호재의 도포조건, 압축강도, 부착강도, 화학저항성, 염해저항성 등을 모두 고려하여 볼 때, 본 연구범위에서는 유황폴리머에 채움재로서 규사와 플라이애시를 각각 20%씩 대체하는 것이 적절한수준인 것으로 판단된다.