As the demand for appropriate heat dissipation measures to improve product stability and performance continues to increase and product design becomes highly integrated, research to improve heat transfer performance while maintaining the same area or size is required. In this study, the sample-shaped aluminum plate was treated as upper-coating, and the thickness of the coating was divided into 1mm, 2mm, and 3mm, respectively, and the coating material was applied with silver, copper, and graphene. The temperature condition of the heat source was set to 473K, and heat dissipation analysis was performed under natural convection. The thermal performance was compared and analyzed through temperature distribution, flow velocity distribution, and heat flux, and it was confirmed that the high thermal conductivity of graphene compared to other materials had a dominant effect on the increase in the conduction heat transfer rate. And it was confirmed that the high surface temperature of the graphene coating also increased the heat transfer rate by convection, thereby enhancing the heat dissipation effect.

피마자 기반 수성 폴리우레탄(CPUD)을 얻기 위해 무 변성 피마자유 (CO) 와 투명 필름을 얻기 위해 이소포론 디이소시아네이트(IPDI)를 사용했다. 유연성을 증가시키기 위해 폴리프로필렌글리콜 (PPG)의 혼합 효과를 분석하였다. 또한, 사슬연장제로 에틸렌다이아민(EDA)을 사용했다. 각각 피마자유 함유에 따른 변화와 사슬연장제 변화에 따른 인장강도, 연신율 내마모성을 측정했다. 피마자유 함유가 많은 시료의 인장강도가 1.112kgf/㎟, 연신율 88%로 나타났으며, 사슬연장제 함유가 많은 시료의 인장 강도가 3.33kgf/㎟, 연신율 99%로 측정되었다. 표면강도는 SEM을 통해 육안으로 확인하였다.

Carbon fiber and its composites are increasingly used in many fields including defence, military, and allied industries. Also, surface quality is given due importance, as mating parts are used in machineries for their functioning. In this work, the turning process is considered for Carbon Fiber Reinforced Polymer (CFRP) composites by varying three important cutting variables: cutting speed, feed, and depth of cut. Correspondingly, the surface roughness is measured after the completion of turning operation. As well, a prediction model is created using different fuzzy logic membership function and Levenberg–Marquardt algorithm (LMA) in artificial intelligence. Later, the surface roughness values from the developed models are compared against the experimental values for its correlation and effectiveness in using different membership functions of fuzzy logic and ANN. Thus, the experimental results are analyzed using the effect graphs and it is presented in detail.

In the field of length, a gauge block is one of the representative gauges used as a standard for length. The main management items of the gauge block are central length, flatness, parallelism, hardness, and surface by visual inspection. The surface of the gauge block may wear over time due to repeated wringing. This phenomenon may deteriorate the precision accuracy and affect the reliability of the measurement results. In this study, the parameters of the surface roughness of the gauge blocks used repeatedly for about 10,000 hours were analyzed. The paired t-test of population mean difference was compared by using the gauge block that has changed over the years as a preliminary experiment and the gauge block with little frequency of use for less than 1 year as the reference value.

해수면온도는 해양-대기 상호작용, 열속 변화, 대양의 해양 순환을 이해할 수 있는 가장 중요한 해양 변수들 중의 하나이다. 0oC 이하 −2oC까지 극저 해수면온도는 기후변화 및 지구환경 변화를 유도하고 조절하기 때문에 다른 범위의 해수면온도보다 더 중요하게 다루어져야 한다. 전구 대양에서 이러한 극저 해수면온도의 시간적 공간적 변동성을 이해하기 위하여 1982년부터 2018년까지의 기간 동안 관측된 인공위성 일별 해수면온도 데이터베이스를 활용하여 평균 기후장을 산출하였다. 또한 장기간의 해양 실측 자료에 기반하여 생산된 표층 수온의 기후 평균장을 활용하여 극저 해수면온도가 전구 대양에서 존재하는 해역과 0oC 등온선의 월별 공간 변동을 분석하였다. 그 결과 극저 해수면온도는 북극해와 남극해와 같은 극지 해역과 고위도의 연해에서 상당한 해양의 표면적을 차지하고 있었다. 이러한 극저 해수면 온도가 어떻게 시각화되어 있는지 검토하기 위하여 6종 지구과학교과서를 분석하였다. 대부분의 교과서에서 해수면온도 삽화는 0oC 혹은 그 이상 수온에서 부터 도시하여 학생들이 극저 해수면온도에 대한 개념과 역할에 대한 이해를 획득 하는 것을 저해하고 있었다. 데이터 시각화는 데이터 리터러시의 주요한 요소 중에 하나이므로 위성 해수면온도 자료가 교과서에 적절하게 시각화되도록 교과서 삽화의 개선이 필요하다. 본 연구는 인공위성 해수면온도 자료와 해양 실측 자료를 활용하여 해양 데이터의 시각화를 통하여 해양학적 소양과 데이터 리터러시가 동시에 함양되고 강화될 수 있음을 강조하였다.

탄소 양자점 (CQDs, Carbon Quantum Dots)은 크기에 따라 광 물리적 특성이 다르게 나타나는 소재로 각광을 받고 있지만 용매의 호환성과 화학적 안정성은 개선해야 할 문제로 남아있다. 따라서 CQDs에 여러 소수성 기능기를 도 입하여 고분자 미셀 내부에 들어갈 수 있도록 표면을 개질하였다. 탄소 양자점이 함유된 고분자 미셀의 광 물리적 특성은 흡광, 형광 분광법으로 측정하였다.

Site characterization for decommissioning Kori Unit 1 is ongoing in South Korea after 40 years of successful operation. Kori Unit 1’s containment building is assumed to be mostly radioactively contaminated, and therefore radiation exposure management and detailed contamination investigation are required for decommissioning and dismantling it safely. In this study, site-specific Derived Concentration Guideline Levels (DCGLs) were derived using the residual radioactivity risk evaluation tool, RESRAD-BUILD code. A conceptual model of containment building for Kori Unit 1 was set up and limited occupational worker building inspection scenario was applied. Depending on the source location, the maximum contribution source and exposure pathway of each radionuclide were analyzed. The contribution of radionuclides to dose and exposure pathways, by source location, is expected to serve as basic data in the assessment criteria of survey areas and classification of impact areas during further decommissioning and decontamination of sites.

The life span of many engineering components depends upon their surface properties. The improved surface properties of the materials are essential for enhancing the mechanical and tribological performance of the material. In many applications, the components required only improved surface properties without changing the entire volume properties of the material. The friction stir process (FSP) is a novel processing technique for the fabrication of such surface composites. In the present investigation, the surface composites were fabricated by incorporating molybdenum disulfide ( MoS2) and graphite (Gr) as reinforcement on the surface of aluminum alloy (Al 1120) through the friction stir process (FSP) at tool rotational speed of 1400 rpm and tool feed rate of 40 mm/min process parameters using square profile FSP tool. The tribological behaviors of fabricated surface composites were calculated by using a pin on disk tribometer. It was observed that the wear resistance of surface composites improved as compared to the matrix material.

CNC cutting process has been mainly used for processing metal materials, and wood processing is also changing to machining by CNC machine. But the researches on the CNC machining of wood and its characteristics were rarely carried out. In this study, we analyzed the machined surface according to the cutting conditions such as the cutting direction, spindle speed, feed rate, cutting depth, chip removal in the CNC machining of wood. The consideration of cutting conditions and their effects on the surface finish will provide possibilities for improving the wood machining processes.

철도 분기기는 결선부와 곡선부의 존재로 인하여 선로에서 가장 손상이 많이 발생하는 구간이며, 구조적 건전성을 유지관리하기 위하여 매년 상당한 비용이 투입되고 있다. 레일연마는 이러한 분기기의 레일 손상을 감소시켜 유지관리 비용을 저감할 수 있는 방안 중 하나로 알려져 있으나, 현재까지 국내에서는 분기기 레일 연마를 통한 유지관리 비용 절감 효과를 정 량적으로 연구한 사례가 거의 없는 상황이다. 이 논문에서는 분기기 레일 연마를 통한 유지관리 비용 절감 효과를 다물체 동적 해석프로그램인 VI-Rail을 이용하여 검토하였다. 레일 연마 효과는 레일 표면의 조도를 이용하여 모사하였으며, VI-Rail 프로 그램의 Flextrack 모델을 이용하여 차량-궤도 상호작용해석을 수행하였다. 수치해석은 60kg #8 분기기와 EMU 차량 모델을 이용 하여 수행하였으며, 레일 표면 조도는 실제 궤도에서 측정된 값을 기반으로 작성한 PSD 함수를 이용하여 모사하였다. 해석 결 과 레일 연마는 분기기 레일의 피로 수명을 6.5% 가량 증가시키는 것으로 나타났다.

황색점착트랩의 설치각도에 따른 고설재배 딸기의 주요 해충종들의 부착 특성을 확인하기 위해 수직, 수평 앞면 및 뒷면, 45도 앞면 및 뒷면 등으로 달리 트랩을 설치하여 점착트랩내의 부착위치를 조사하고, 각 트랩에 포획된 곤충종의 다양성을 분석하였다. 설치각도에 따른 점착트랩 내의 포획 위치는 진딧물류와 총채벌레류가 유사하게 모든 각도에서 상부에서 유살수가 많았으나 유의한 차이는 나타나지 않았다. 수직, 45도 윗면 트랩에서 종수와 총포획수가 유의하게 높았으나 각 처리별 Shannon 지수의 차이는 없었다. 45도 윗면 트랩에서만 Shimpson 지수가 높게 나타나 소수 종에 집중된 포획양상을 보였으며 모든 트랩에서 공통적으로 초파리와 총채벌레류가 우점하여 포획되었으나 총포획수가 적은 45도 아랫면 트랩의 경우 이들 우점종의 검출도가 낮았다.

A number of studies on airborne pollutants and microorganisms using ultraviolet sterilization have been conducted. Countermeasures are also needed to be taken against contamination and damage that occur on indoor surfaces in addition to indoor air. In this study, a method to predict UV-C intensity distribution using radiance calculation was introduced for the purpose of surface sterilization using UVGI systems and compared with the measured UVC intensities in a kitchen model room. The results of calculations showed a similar distribution of ultraviolet intensity with the measured intensities, although there was some discrepancy, probably due to different reflectance of building materials. And some bacteria and viruses occasionally identified in kitchens were predicted to be sterilized 99.9% only after about 30 minutes of UV-C irradiation with the figure 90% for fungi. The sterilization performance of UVGI and exposure time to UV-C were reasonably predicted using the radiance calculation method, and UV sterilization can be achieved with great effect even after a short period of time.

PURPOSES: This study aimed to evaluate the performance of a model developed for road surface temperature change pattern in reflecting specific road characteristics. Three types of road sections were considered, namely, basic, tunnel, and soundproof tunnel. METHODS: A thermal mapping system was employed to collect actual road surface temperature and locational data of the survey vehicle. Data collection was conducted 12 times from 05:30 am to 06:30 am on the test route, which is an uninterrupted flow facility. A total of 9010 road surface temperature data were collected, and half of these were selected based on a random selection process. The other half was used to evaluate the performance of the model. The model used herein is based on machine learning algorithms. The mean absolute error (MAE) was used to evaluate the accuracy of the estimation performance of the model. RESULTS: The MAE was calculated to determine the difference between the estimated and the actual road surface temperature. A MAE of 0.48℃ was generated for the overall test route. The basic section obtained the smallest error whereas that of the tunnel was relatively high. CONCLUSIONS: The road surface temperature change is closely related to the air temperature. The process of data pre-processing is very important to improve the estimation accuracy of the model. Lastly, it was difficult to determine the influence of the data collection date on the estimation of the road surface temperature change pattern due to the same weather conditions.