Using porous asphalt in order to reduce traffic noise and increase road safety specially in rainy weather is become a time demand now a days. Traditional dense asphalt can not provide a well mannered drain systems, adequate road capacity and noise friendly environment, which can make harm to roadway, property and ultimately to the life. In contrast, porous asphalt provides a environment friendly, cost effective, high skid resistive and well drains pavement with great durability. Additionally, the ability of porous to decrease the number of crashes both in sunny and wet-weather are up to the mark. In this context, investigate the ability of porous asphalt allows for deeper insights into all the mentioned factors, which help to make a durable, time demandable, more safer pavements in the field of pavement engineering. By combining some lab tests, field tests and analyzing the data, this research offers more accurate and reliable results to lead a pavement situation adaptable.

본 논문에서는 전산점근해석기법을 사용하여 복합재료 보에 대한 경계층 해를 계산하고, ANSYS 결과와 비교 검증하였다. 경계층 해는 내부해와 순수 경계층 효과의 합으로 표현되기 때문에, 내부 및 경계층에 대한 수학적으로 엄밀한 정식화를 요구한다. 전산점근 해석기법은 수학적으로 매우 강력한 기법으로, 이러한 문제에 유용하다. 그러나 경계층과 내부 해들의 연결을 시키기 쉽지 않은데, 본 연구에서는 가상일의 원리를 통해 생브낭의 원리와 내부 및 경계층 문제를 체계적으로 분리하였다. 경계층 해는 팝코비치-패들 고유 벡터를 계산하여, 실수부와 허수부 벡터들의 선형 조합으로 표현하고, 내부 해의 워핑 함수들을 보상할 수 있도록 최소오차 자승법을 적용하였다. 계산된 해들은 2차원 유한요소 해석 결과와 비교하여 정성적일 뿐만 아니라 정량적으로도 잘 일치하는 결과를 얻었다.

It has been known that as oxide layer (ZrO2) forms on the nuclear fuel cladding during irradiation in nuclear power plants, the corrosion kinetics are influenced by various parameters such as chemical environments. One of those environments, crud deposition driven by coolant chemistry has an adverse effect on the formation of oxide (ZrO2) and leads to increase thickness of the layer. In this study, crud formation was performed through loop experiment equipment on the surface of intentionally-made oxide layer (ZrO2) on cladding tubes and then the composition and characteristics of cruds were examined for the investigation of nuclear power plant environment. As a result, various cruds in composition and microstructure were formed depending on the exquisite methods and conditions such as metal ion concentration.

The automotive industry continuously strives to enhance safety for both drivers and passengers through technological advancements. Car side impacts have the potential to significant risks to passengers, So the automotive industry has proposed various technological solutions. As part of these efforts, the development of side impact beams, which are affixed to the inner frame of vehicle side doors to absorb and dissipate collision energy, has been a safety enhancement. Conventional side impact beams are manufactured using hot-rolled steel sheets and have a pipe-like configuration. However, these impact beams are fixed to the vehicle's chassis, which directly transfers the energy generated during a collision to the chassis frame. This paper aims to address this issue by proposing the development and optimization of vehicle door impact beams using a dual-beam structure and fastening method, utilizing shear bolts. Moreover, the focus is on optimizing the cross-sectional shape of the dual-beam impact structure. The evaluation criterion for optimization is based on the second moment of area of the cross-section. To validate these improvements, Static experiments were conducted, comparing the proposed dual-beam structure with the traditional impact beam. This research is expected to serve as a guideline for enhancing vehicle safety through design directions and validation methods.

Hydrogen is considered as one of the most promising future energy carriers due to its noteworthy advantages of renewable and high calorific value. The long-term storage of liquid hydrogen with low heat leakage is essential for future deep space exploration. Because of low critical temperature and volatility, liquid hydrogen tank poses severe requirements to multi-layer insulation (MLI). In order to reduce heat leak into tank, vapor cooled shield (VCS) was set up to cool MLI by retrieving the heat of discharged cryogenic gas hydrogen. This paper presents an parametric study on insulation system in liquid hydrogen storage vessel with MLI and VCS. Thermal model was developed, and heat transfer analysis by varying VCS position was conducted. Temperature and heat flux distributions along time passing were derived, and effect of VCS position on insulation performance was investigated.

The most comprehensive and particularly reliable method for non-destructively measuring the residual stress of the surface layer of metals is the sin method. When X-rays were used the relationship of sin measured on the surface layer of the processing metal did not show linearity when the sin method was used. In this case, since the effective penetration depth changes according to the changing direction of the incident X-ray,  becomes a sin function. Since  cannot be used as a constant, the relationship in sin cannot be linear. Therefore, in this paper, the orthogonal function method according to Warren’s diffraction theory and the basic profile of normal distribution were synthesized, and the X-ray diffraction profile was calculated and reviewed when there was a linear strain (stress) gradient on the surface. When there is a strain gradient, the X-ray diffraction profile becomes asymmetric, and as a result, the peak position, the position of half-maximum, and the centroid position show different values. The difference between the peak position and the centroid position appeared more clearly as the strain (stress) gradient became larger, and the basic profile width was smaller. The weighted average strain enables stress analysis when there is a strain (stress) gradient, based on the strain value corresponding to the centroid position of the diffracted X-rays. At the 1/5 max height of X-ray diffraction, the position where the diffracted X-ray is divided into two by drawing a straight line parallel to the background, corresponds approximately to the centroid position.

Double-layer capacitors (DLCs) are developed with high surface electrodes to achieve a high capacitance value. In the present work, the initial bulk concentration of 1 mol/m3 and 3 mol /m3 are selected to show the consequential effects on the performance of a double-layer capacitor. A 1D model of COMSOL Multiphysics has been developed to analyze the electric field and potential in cell voltage, the electric displacement field and polarization induced by the field, and energy density in a double-layer structure. The electrostatics and the electric circuit modes in COMSOL are used to simulate the electrochemical processes in the double-layer structure. The analytical analysis of a double-layer capacitor with different initial bulk concentrations is investigated by using Poisson-Nernst-Plank equations. From the simulation results, the differential capacitance changes as a function of compact layer thickness and initial bulk concentration. The energy density varies with the differential capacitance and voltage window. The values of energy density are dominated by the interaction of ions in the solution and electrode surface.

현재 고려되고 있는 단층 심지층처분장 개념은 부지 소요면적이 지나치게 크기 때문에, 처분밀도를 향상시키기 위한 다층 심지층처분장 개념이 제안되고 있다. 심부암반에 건설된 다층 심지층처분장 주위에 형성된 암반손상대가 심지층처분장의 온도 분포에 미치는 영향이 분석되었다. 다층 심지층처분장의 열해석에는 완충재, 뒤채움재 및 암반에서 일어나는 재포화 현상을 고려한 열-수리 모델이 사용되었다. 암반손상대의 존재는 심지층처분장의 온도 분포에 큰 영향을 미치는 것으로 나 타났으며, 손상대의 크기와 열전도도 저하 정도에 따라 복층 및 삼층 심지층처분장의 최고첨두온도를 각각 최대 7℃와 12℃ 까지 증가시킬 수 있다. 다층 심지층처분장의 첨두온도에 영향을 크게 미치는 인자는 암반손상대에서의 열전도도 저하이며, 처분공 주위에 형성된 암반손상대가 처분터널 주변에 형성된 암반손상대보다 첨두온도에 더 큰 영향을 미친다.

of the marketed multi-later insulating curtain was carried out. Experiments is conducted by fabricating a test apparatus for investigating the heat flux characteristics. The multi-later insulating curtain used for the experiment was compared using the P, N, S, U and T company, which are commercially available, and the heat flux due to temperature difference between the experimental apparatus and the outside was compared and analyzed. When the internal temperature of the experimental result is the maximum temperature 60℃, the heat flux of multi-later insulating curtain is T Co.(73.1W/m2) > S Co.(119.5W/m2) > U Co.(155W/m2) > N Co.(163.1 W/m2) > P Co.(177.7W/m2). The heat flux means the quantity of heat passing through the unit time per unit area, and the higher the numerical value, the higher the quantity of heat passing through the multi-layer insulating curtain. This can be determined that high heat fluxes produce low heat resistance. Further, it has been found that the weight of the insulating curtain is largely unrelated to the heat insulating property, and the heat insulating curtain having a thickness containing a high internal air layer is excellent in the heat insulating property. In the future when manufacturing a heat insulating curtain, It is judged that it is desirable to manufacture a combination of heat insulating materials that contain a high internal air layer content and that can maintain the air layer even for long-term use while minimizing the volume.

The objective of this study is to investigate the response reducing effect of a seismic isolation system installed between 300m dome and supports under both horizontal and vertical seismic ground motion. The time history analysis is performed to investigate the dynamic behavior of single layer lattice domes with and without a lead rubber bearing seismic isolation system. In order to ensure the seismic performance of lattice domes against strong earthquakes, it is important to investigate the mechanical characteristics of dynamic response. Horizontal and vertical seismic ground motions cause a large asymmetric vertical response of large span domes. One of the most effective methods to reduce the dynamic response is to install a seismic isolation system for observing seismic ground motion at the base of the dome. This paper discusses the dynamic response characteristics of 300m single layer lattice domes supported on a lead rubber seismic isolation device under horizontal and vertical seismic ground motions.

Asphalt pavement overlay method is one of widely chosen construction methods for remodelling existing aged concrete pavement layer. However, in this case reflective cracking is a challenging issue due to movement of transverse joints: built in existing concrete pavement layer with constant interval length. In this paper, collecting field data: collection of displacement and temperature data on existing concrete pavement layer for further complicated pavement performance analysis, was performed. To fulfil this objective, various types of thermometer were embedded into concrete layer with different depth level. Then, movement of existing concrete layer was measured numerically. Each Displacement Measuring Gauge (DMG) along with thermometer was embedded with depth of 3cm and 15cm, respectively. Additional thermometers were embedded at the middle depth of overlaid asphalt pavement layer for further extensive analysis and data collection. Total four testing sites were considered based on different asphalt mixture type and construction method. The 1st site was constructed with conventional construction approach, the 2nd site was constructed with a new pavement equipment contains simultaneous tack-coating function, the 3rd site was similar to 1st site but Guss-asphalt was constructed as a binder course, and in 4th site Noise-Reduction Porous Asphalt (NRPA) was constructed as a surface course and regular Dense Grade Asphalt (DGA) was constructed as a binder course. A field asphalt pavement layer sample coring works: along with basic material property tests, were also performed to acquire not only overlaid asphalt but also existing concrete pavement materials. This gauge measuring work in this study is an initial step therefore, long-term movement data of each pavement layer was not able to be collected, unfortunately. However through collecting and analysing initial data on each test site, two crucial findings were acquired. First, in all four tested site highest temperature variations were observed at the upper asphalt pavement layer and the variation trends decreased with increase of pavement depth (in case of concrete pavement layer, temperature and movement variations also decreased with increase of pavement depth). Secondly, when Guss-asphalt was applied as a binder course temperature variations of existing concrete pavement layer was crucially smaller than those of other comparison cases. These current findings and collected data set can provide successful input information for further pavement structure analysis such as 2D (and/or 3D) Finite Element Method (FEM) analysis as a future study.

In Korea, concrete pavements were first applied to highways in 1981 and as a result of continued increase in length over the past years, 2,592 km of concrete pavement network is currently in service, of which 1,399 km(54%) of concrete pavements is 10 years or older, and 233km(9%) is 20 years or older. The length of concrete pavement sections nationwide has been steadily on the rise every year (EXTRI, 2017). Approximately 54% of current concrete pavement highway network will reach the service life limit in 2025 which means around 660 billion won is needed for future pavement repair project (EXTRI, 2017). Given that concrete pavements beyond design life still have a remaining service life, it is economically advantageous to repair them before reconstruction. Asphalt overlays are a major repair method for older concrete pavements. Depending on the concrete pavement condition, thickness and mixture of asphalt overlays are determined. Service life of asphalt overlays varies by the presence, time and size of cracks in existing concrete pavements and reflecting crack at joints. Temperature change of concrete pavement is among the major reaction parameters of reflecting crack. Reflecting crack develops when asphalt bottom-up cracking by longitudinal shrinkage and expansion due to temperature change of the concrete base layer, top-down cracking by temperature difference between top and bottom of concrete, and shear stress by traffic loading are combined (Baek, 2010). Crack and joint behaviors of concrete pavement vary between the base layer and the concrete surface of composite pavement system, and different conductivity by mixture and thickness of asphalt overlay leads to temperature change of concrete base course. This study measured temperatures of each layer of diverse composite pavements in place on site and analyzed differences in temperature change of concrete base layer depending on mixture and thickness of asphalt overlays. Overlay thickness parameters were 5cm and 10cm, two values most widely used, while mixture parameters were SMA and porous asphalt. Based on temperature change of concrete surface, this study also evaluated the difference of temperature change in concrete base layer with an asphalt overlay on top. Findings from this study are expected to be utilized for studies on mechanism and modeling of reflecting crack in old concrete pavements with asphalt overlays.

PURPOSES : The purpose of this study is to compare noise reduction quantities between before/after two-layer low noise pavement implementation using equivalent noise level analysis and to analyze the noise reduction effects of the two layer low noise pavement with a statistical method such as the Anderson-Darling Test.METHODS: In order to compare and to analyze noise reduction effects between before/after two-layer low noise pavement implementation, data acquisition as noise levels on a roadside and an apartment rooftop was conducted in the study area. The equivalent noise level was estimated in order to compare noise reduction quantities and the Anderson-Darling Test was carried out for estimating noise reduction effects of the two-layer low noise pavement.RESULTS: The equivalent noise levels of before/after two-layer low noise pavement implementation for the roadside during the daytime are 65.355 dB and 63.520 dB and during the nighttime are 62.463 dB and 59.088 dB. The equivalent noise levels for the apartment rooftop during daytime are 57.301 dB and 59.088 dB and during the nighttime are 54.616 dB and 52.464 dB. Also two-layer low noise pavement decreased the noise reduction effects estimated with the statistical method as the Anderson-Darling test for the roadside during the daytime by around 66.68% and decreased noise reduction effects on the roadside during the nighttime by 0.70%. Moreover it reduced noise reduction effects in the apartment rooftop during the daytime and nighttime by 0% and 96.32%, respectively.CONCLUSIONS : Based on the result of this study, two-layer low noise pavement can positively affect noise reduction during both the daytime and nighttime according to the results of estimating the equivalent noise levels and the Anderson-Darling test.

Recently, the use of an aluminum nitride(AlN) buffer layer has been actively studied for fabricating a high quality gallium nitride(GaN) template for high efficiency Light Emitting Diode(LED) production. We confirmed that AlN deposition after N2 plasma treatment of the substrate has a positive influence on GaN epitaxial growth. In this study, N2 plasma treatment was performed on a commercial patterned sapphire substrate by RF magnetron sputtering equipment. GaN was grown by metal organic chemical vapor deposition(MOCVD). The surface treated with N2 plasma was analyzed by x-ray photoelectron spectroscopy(XPS) to determine the binding energy. The XPS results indicated the surface was changed from Al2O3 to AlN and AlON, and we confirmed that the thickness of the pretreated layer was about 1 nm using high resolution transmission electron microscopy(HR-TEM). The AlN buffer layer deposited on the grown pretreated layer had lower crystallinity than the as-treated PSS. Therefore, the surface N2 plasma treatment on PSS resulted in a reduction in the crystallinity of the AlN buffer layer, which can improve the epitaxial growth quality of the GaN template.

PURPOSES : Nowadays, cavity phenomena occur increasingly in pavement layers of downtown areas. This leads to an increment in the number of potholes, sinkholes, and other failure on the road. A loss of earth and sand from the pavement plays a key role in the occurrence of cavities, and, hence, a structural-performance evaluation of the pavement is essential. METHODS: The structural performance was evaluated via finite-element analysis using KPRP and KICTPAVE. KPRP was developed in order to formulate a Korean pavement design guide, which is based on a mechanical-empirical pavement design guide (M-EPDG). RESULTS: Installation of the anti-freezing layer yielded a fatigue crack, permanent deformation, and international roughness index (IRI) of 13%, 0.7 cm, and 3.0 m/km, respectively, as determined from the performance analysis conducted via KPRP. These values satisfy the design standards (fatigue crack: 20%, permanent deformation: 1.3 cm, IRI: 3.5 m/km). The results of FEM, using KICTPAVE, are shown in Figures 8~12 and Tables 3~5. CONCLUSIONS: The results of the performance analysis (conducted via KPRP) satisfy the design standards, even if the thickness of the anti-freezing layer is not considered. The corresponding values (i.e., 13%, 0.7 cm, and 3.0 m/km) are obtained for all conditions under which this layer is applied. Furthermore, the stress and strain on the interlayer between the sub-grade and the anti-freezing layer decrease gradually with increasing thickness of the anti-freezing layer. In contrast, the strain on the interlayer between the sub-base and the anti-freezing layer increases gradually with this increase in thickness.

Nowadays, the study of CFRP reinforced with carbon fiber is focused on improving the the mechanical property. The study on the fracture data of CFRP are not properly made out than that of the general mechanical joint. In this study, the fracture property of mode 1 at the same condition of tensile experiment is investigated by applying the layer angle to laminated CFRP with the thickness of 15 mm. When the reaction forces until dropping out the bonded surface are compared with the cases of the layer angles of 0°, 45° and 60°, the reaction force is shown to be most and the elapsed time until dropping out the bonded surface is longest at that of 45°. The deformation energy is also shown to have the highest value by dropping out the adhesive interface. As the basis of the analysis result of this study, the most safety with fracture resistance is shown in the case of 45°. the bonded structure applying the appropriate layer angle is thought to have the structural safety.

기술 표준은 기술적 특성과 사양에 대한 일종의 사회적 합의로서 기술의 발달 과 함께 모든 산업에 걸쳐 존속되어 왔으며 최근에는 정보통신 기술의 발달과 함께 기술의 상호호환성을 제공하고 시장의 우위를 선점할 수 있는 전략적인 요소로 각광받고 있다. 이에 기술 표준 연구(표준화 연구)는 기술 표준의 채택 과정과 이로 인한 경제적 효과를 분석하여 이론적 및 정책적 함의를 도출하는데 그 의의가 있다. 그러나 기존의 연구에서는 기술 고유 의 가치와 상호호환성에 대한 고려가 부족하다는 점에서 기술 중심의 분석 결과를 도출하는 데 있어 구조적 한계를 드러낸다. 본 연구는 기술 네트워크 분석을 통해 도출한 기술 차별화 정도와 기업별 기술 선호도 함 수를 두 단계 게임 이론 분석 방법에 반영하여 새로운 기술 중심 표준 연구 방법론을 제공하는 것을 목적으로 하고 있다. 그 실증 사례로 사물인터넷의 무선 팬 기술을 선정하였으며, 본 연구 방법론을 통해 해당 시장의 기술 구조 및 표준 관련 함의를 도출하였다.

This study analyzed the growth characteristics of multi-layer planted trees through their growth analysis and attempted to present a management strategy. The subject of research is the Citizen's Forest Area of Seoul Forest Park located in Seoul City. Field surveys were conducted three times over eight years from 2005 when the Seoul Forest Park was created through 2013. Labels were attached to all trees in the target area, and their species, height and DBH were investigated. To identify the growth differences by trees in each area, a detailed tree location map was drawn up for use in the analysis. To check soil health, soil organic matter, soil pH and soil microbial activities were analyzed. It turned out that the growth of the multi-layer planted trees in the target area of research was higher than that of the trees in existing urban parks, and that it was similar to that of trees in natural forests. Through a field survey in the area with a remarkably low growth, high-density planting problem, soil was found to have excess-moisture and there was the problem of Pueraria lobata covering. As a result of the analysis of the soil, it was found that its organic content in the soil was lower; soil pH was higher; and microbial activities in the soil were lower when compared to that of natural forests.

In this study, in order to improve the efficiency of n-type monocrystalline solar cells with an Alu cell structure, we investigate the effect of the amount of Al paste in thin n-type monocrystalline wafers with thicknesses of 120 μm, 130 μm, 140 μm. Formation of the Al doped p+ layer and wafer bowing occurred from the formation process of the Al back electrode was analyzed. Changing the amount of Al paste increased the thickness of the Al doped p+ layer, and sheet resistivity decreased; however, wafer bowing increased due to the thermal expansion coefficient between the Al paste and the c-Si wafer. With the application of 5.34 mg/cm2 of Al paste, wafer bowing in a thickness of 140 μm reached a maximum of 2.9 mm and wafer bowing in a thickness of 120 μm reached a maximum of 4 mm. The study’s results suggest that when considering uniformity and thickness of an Al doped p+ layer, sheet resistivity, and wafer bowing, the appropriate amount of Al paste for formation of the Al back electrode is 4.72 mg/cm2 in a wafer with a thickness of 120 μm.