PURPOSES : For most local governments, including that of Gangwon-do, the establishment of an organized pavement management system is insufficient, resulting in problems such as inefficient distribution and use of maintenance budgets for deteriorated road pavements. In this study, we aimed to contribute to the establishment of a more reasonable road maintenance strategy by developing a model for predicting the annual international roughness index (IRI) change for national highway asphalt pavements in Gangwon-do based on big data analysis. METHODS : Data on independent and dependent variables used for model development were collected. The collected data were subjected to exploratory data analysis (EDA) and data preprocessing. Independent variable candidates were selected to reduce multicollinearity through correlation analysis and specific conditions. A final model was selected, and sensitivity analysis was performed. RESULTS : The final model that predicts annual IRI change uses independent variables such as annual temperature range, minimum temperature, freeze-thaw days, IRI, surface distress (SD), and freezing days. The sensitivity analysis confirmed that the annual IRI change was affected in the order of annual temperature range, minimum temperature, freeze-thaw days, IRI, SD, and freezing days. CONCLUSIONS : Road maintenance can be performed rationally by predicting future pavement conditions using the model developed in this study. The accuracy of the prediction model can be improved if additional data, such as material properties and pavement thickness, are obtained in future studies.

This research measured the change in mechanical characteristics of a sample obtained by finishing a metal coating to an engineering plastic manufactured using a 3D printer to satisfy both lightweight and quality characteristics. High-Temp material, which can be applied to space thermal environments with large temperature fluctuations, was applied as the engineering plastic material, and Stereolithography(SLA) method, which has relatively higher precision than Fused Film Fabrication(FFF) method, was selected as the manufacturing method. Electroless & electroplating were performed by metal coating on the surface to satisfy the characteristics of products requiring electrical conductivity. Tensile and bending tests were conducted to verify a change in the mechanical characteristics of a sample completed with a metal coating, and an adhesion test of the metal coating was also added.

In this study, a graphite block is fabricated using artificial graphite processing byproduct and phenolic resin as raw materials. Mechanical and electrical property changes are confirmed due to the preforming method. After fabricating preforms at 50, 100, and 150 MPa, CIP molding at 150 MPa is followed by heat treatment to prepare a graphite block. 150UP-CIP shows a 12.9% reduction in porosity compared with the 150 MPa preform. As the porosity is decreased, the bulk density, flexural strength, and shore hardness are increased by 14.9%, 102.4%, and 13.7%, respectively; and the deviation of density and electrical resistivity are decreased by 51.9% and 34.1%, respectively. Therefore, as the preforming pressure increases, the porosity decreases, and the electrical and mechanical properties improve.

무등산국립공원의 과거(1966년)와 현재(2017년) 항공사진으로 암설사면 분포면적을 분석했고, 암설사면과 그 일대 의 식생을 조사하여 암설사면의 면적 변화에 영향을 주는 식생의 특성을 알아보았다. 무등산에 외관상 보이는 암설사면 의 면적은 과거보다 ¼수준까지 줄어들었다. 이곳의 암설사면은 51년 동안 식생 피복에 의해 연평균 2.3ha씩 감소했다. 특히, 저지대 완경사지에 소면적의 암설사면은 식생 피복이 활발하여 대부분이 사라졌다. 하지만 서향, 남서향, 남향 그리고 대면적의 암설사면이 남아 있었는데 이는 태양의 복사열이 암괴의 표면온도를 급속도로 상승시켜, 수분 건조에 따른 수목 생육이 불리해졌기 때문이다. 이런 입지특성 때문에 가장 넓은 덕산너덜 중간부의 소규모 식생은 인접한 산림지역과 다른 특성을 보였다. 덕산너덜에는 양지바른 곳이나 내건조성이 뛰어난 수종이 흔하게 출현했다. 하지만, 토양조건이 양호한 계곡부에 잘 자라는 호습성 수종 또한 세력이 우세했다. 이곳 일부에는 암괴 틈사이로 세립물질과 유기물 축적으로 토양층이 발달해 이런 수종이 정착해 자라는 것으로 보인다. 한편, 무등산 정상부에는 산림이 암설사면 을 덮었는데 고지대에 전형적으로 자라는 신갈나무·철쭉이 우세했다. 이곳은 덕산너덜처럼 암괴 밀도가 높지 않고 토양이 드러나, 식생 발달에 유리했다고 본다. 또한 이곳에는 계곡부에 출현하는 물푸레나무와 당단풍나무의 세력이 강했다. 이는 일부 지역에 암괴들이 떨어져 아래에 쌓이면서 원지형을 오목한 형태의 함몰지형으로 만들어, 빗물 집수로 인해 토양수분이 높아졌기 때문이다. 결론적으로 암괴사면의 면적, 암괴밀도, 분포유형이 암설지형에서의 식생발달과 종조성에 지대한 영향을 미쳤다고 본다.

This research studied the electrical characteristics, IR transmission characteristics, stealth functions, and thermal characteristics of infrared thermal-imaging cameras of copper-sputtered samples. Nylon samples were prepared for each density as a base material for copper-sputtering treatment. Copper-sputtered NFi, NM1, NM2, NM3, NM4, and NM5, showed electrical resistance of 0.8, 445.7, 80.7, 29.7, 0.3, and 2.2 Ω, respectively, all of which are very low values; for the mesh sample, the lower the density, the lower the electrical resistance. Measuring the IR transmittance showed that the infrared transmittance of the copper-sputtered samples was significantly reduced compared to the untreated sample. Compared to the untreated samples, the transmittance went from 92.0–64.1%. When copper sputtered surface was directed to the IR irradiator, the IR transmittance went from 73.5 to 43.8%. As the density of the sample increased, the transmittance tended to decreased. After the infrared thermal imaging, the absolute values of △R, △G, and △B of the copper phase increased from 2 to 167, 98 to 192, and 7 to 118, respectively, and the closer the density of the sample (NM5→NFi), the larger the absolute value. This proves that the dense copper phase-up sample has a stealth effect on the infrared thermal imaging camera. It is believed that the copper-sputtered nylon samples produced in this study have applications in multifunctional uniforms, bio-signal detection sensors, stage costumes, etc.

To elucidate how cultivation temperature affected various traits including pileus color, yield and morphology of Pleurotusspp. Main results were as follows. Pileus lightness of all cultivars of Pleurotustested became higher as cultivation temperature increased, while those of Santari, Hwang-geumsantari and Sunjung at 21oC were lower than at 18oC. Redness and yellowness of pileus decreased as cultivation temperature increased; those of chromatic pileus cultivars showed noticeable difference. Yellowness of cultivar with chromatic pileus was higher than that of cultivar with achromatic pileus. Yield was increased as cultivation temperature increased, Wonhyeung 1ho; low temperature favored cultivar showed high yield when it was cultivated at low temperature andno fruiting body at 21oC. Valid number of stipes were generally higher at 18oC, and its correlation coefficient with yield was low. Length and stipe thickness changed consistently (larger and thicker) upon cultivation temperature; the coefficient of determination(R2) 0.514 for lengthof Heuktari and 0.963for stipe thickness of Santari were high. Correlation coefficient of one trait was highly related with multiple traits. In the future, we will conduct research on the changes of expressed genes involved in the pigments for pileus color by RNA expression analysis.

This research investigated how adding Sb (0.75, 1.0, 2.0 and 5.0 wt%) to as-extruded aluminum alloys affected their microstructure, mechanical properties, electric and thermal conductivity. The addition of Sb resulted in the formation of AlSb intermetallic compounds. It was observed that intermetallic compounds in the alloys were distributed homogenously in the Al matrix. As the content of Sb increased, the area fraction of intermetallic compounds increased. It can be clearly seen that the intermetallic compounds were crushed into fine particles and homogenously arrayed during the extrusion process. As the Sb content increased, the average grain size decreased remarkably from 282.6 μm (0.75 wt%) to 109.2 μm (5.0 wt%) due to dynamic recrystallization by the dispersed intermetallic compounds in the aluminum matrix during the hot extrusion. As the Sb content increased from 0.75 to 2.0 wt%, the electrical conductivity decreased from 61.0 to 59.8 % of the International Annealed Copper Standard. Also, as the Sb content increased from 0.75 to 2.0 wt%, the ultimate tensile strength did not significantly change, from 67.3 to 67.8 MPa.

The purpose of this study was to investigate the Maillard reaction–related physicochemical properties of three maize varieties (Kwangpyeongok, Sinhwangok2ho and Gangdaok) after roasting them for different times (0, 15, 25, 40, and 55 minutes). The Maillard reaction is a non-enzymatic browning reaction involving reducing sugars and amino compounds. The content of reducing sugar, the causative agent of the Maillard reaction, decreased as roasting time increased. Gangdaok showed the lowest reducing sugar content of 1.04 mg/g after 55 minutes of roasting. In the elapsed roasting time, chromaticity ‘L’ and ‘b’ values decreased. At 55 minutes of roasting, wherein the Maillard reaction occurred most actively, Gangdaok showed the lowest ‘L’ value of 56.37 and the highest ‘a’ value of 7.60. Gangdaok had superior conditions for inducing the Maillard reaction compared to other varieties, and it is consider that 'flint–type', an endosperm characteristic, may have been the influencing agent. This study detected a total of 52 types of volatile aroma compounds (VACs), of which 28 were produced after roasting. Of the total VACs detected, 2-Formyl-5-methylfuran and 2-Furancarboxaldehyde accounted for 43.8~45.5% and have been confirmed to be the major VACs present in roasted maize. Most of the correlations between the Maillard reaction–related characteristics showed high correlation coefficients.

영농형 태양광 발전은 농경지에서 작물을 생산함과 동시에 식물이 요구하는 광포화점 이상의 광을 이용하여 전기를 생산 하는 시스템이다. 새로운 농가 소득원의 개발을 위하여 포도 원에 태양광 패널을 설치하고 수체의 생육과 과실 발육 특성 을 평가하여 영농형 태양광의 활용성을 탐색하고 향후 재배기 술을 개발하는 데 필요한 정보를 제공하고자 연구를 진행하였 다. 152 × 68 × 3.5cm 크기의 구조물에 영농형 150Wp (36cell) 모듈을 포도나무 재식열에 따라 배치하고, 과원의 환경과 식물 생육을 분석하였다. 무처리에는 겨울철 풍속이 0.4－0.6m·s-1 에 도달하였으나, 시설 설치구에서는 0.01－0.02m·s-1에 머 물렀다. 삽수 수피의 탄수화물함량은 시설 설치구에서 183－ 184m·g-1으로 무처리구(181－198mg·g-1)에 비해 큰 차이가 없으며 삽수의 발아율도 큰 차이가 없었다. 잎의 엽록소의 함 량은 처리구에서 높게 나타났다. 수확후 과실의 특성으로는 과립중, 과방중, 당도, 과피색의 차이는 없었다. 다만 시설구 에서 숙기가 5－7일정도 늦어졌으며, 변색기의 착색에는 약 간 차이가 있었다. 영농형 태양광 패널을 설치한 과원에서 포 도나무와 과실의 발육은 유의차가 없었고, 설치구에서 착색 이 지연되었다. 이러한 결과는 향후 포도원에서 영농형 태양 광 시설을 설치하여 포도를 생산하는 기술 개발에 필요한 정 보로 활용될 수 있을 것이다.

In this study, Barium Germanium glasses were prepared with a composition of xBaO-(72-x)GeO2-8La2O3-20ZnO where x = 16.0, 18.0, 20.0, 22.0 and 24.0 mol% respectively. Their physical and optical properties, such as refractiveness index, glass transition temperature (Tg), softening temperature (Ts), transmittance and Knoop hardness were studied. The results showed that refractive index, Tg, Ts and coefficient of thermal expansion (CTE) increased with increasing BaO concentration. The refractive index of all the prepared samples was observed between 1.7811 to 1.7881. The Abbe number was calculated by formula using nd (589.3 nm), nf (656.3 nm) and nc (486.1 nm) and observed to be between 38 to 40. The Abbe number of the prepared sample was similar to that of BaO and GeO2. The transmittance of the prepared glasses was observed to be between 80 ~ 82 % throughout the range from 200 nm to 800 nm. Knoop hardness divided into seven steps were measured 5 class (≥ 450 ~ < 550) of all prepared samples.

반추위 미생물체 단백질의 아미노산 조성이 한우의 에 너지원 사료에 따라 차이가 있는지를 조사하고자 본 연구 가 수행되었다. 본 실험은 국내 한우 비육우 사육에 주로 이용되는 에너지원 사료인 옥수수(T1), 생미강(T2), 소맥 (T3), 소맥피(T4)를 이용하여 in vitro 반추위 발효실험을 진행하여 발효 24시간 후 배양액의 발효 성상, 미생물체 단백질 합성량(MPS), 미생물의 아미노산 조성 및 미생물 균총 변화를 분석하였다. 배양액의 pH는 T4가 6.02로 다 른 처리구들에 비해서 가장 높았으며, T1은 4.84로 가장 낮았다(p<0.05). Total VFA 농도는 T2가 96.80mM로 다른 처리구들에 비해서 가장 높았고, T1이 53.35mM로 가장 낮았다(p<0.05). 미생물체 단백질 합성량은 T3가 222.50g/L로 다른 처리구들에 비해서 높았으며(p<0.05), T1과 T4는 유의적인 차이는 없었지만 T1이 가장 낮았다. DGGE band 분석결과 모든 처리구는 57.5% 이하의 유사도를 나타내었으며, 급여되는 사료에 따라서 미생물 군집 이 다르게 나타났다. 미생물 내 총 아미노산 함량은 T3와 T4가 다른 처리구보다 높았다(p<0.05). 미생물의 아미노산 조성 중 대부분의 필수 아미노산은 T4가 다른 처리구들에 비해서 낮았다. 하지만 methionine은 다른 필수 아미노산 과 다르게 T4에서 가장 높았다(p<0.05). 곡류 사료 위주의 급여 시 결핍되기 쉬운 lysine은 모든 처리구에서 미생물 의 아미노산 조성이 8.05~8.98%의 범위에 있었다. 따라서, 본 연구에서 반추 가축 급여 에너지 사료원에 따른 반추 위 내 미생물 발효특성과 미생물 군집의 차이가 미생물의 아미노산 조성을 변화시킨다는 것을 확인하였다.

Beta-titanium alloys are used in many industries due to their increased elongation resulting from their BCC structure and low modulus of elasticity. However, there are many limitations to their use due to the high cost of betastabilizer elements. In this study, biocompatible Ti-Mo-Fe beta titanium alloys are designed by replacing costly betastabilizer elements (e.g., Nb, Zr, or Ta) with inexpensive Mo and Fe elements. Additionally, Ti-Mo-Fe alloys designed with different Fe contents are fabricated using powder metallurgy. Fe is a strong, biocompatible beta-stabilizer element and a low-cost alloying element. The mechanical properties of the Ti-Mo-Fe metastable beta titanium alloys are analyzed in relation to the microstructural changes. When the Fe content increases, the tensile strength and elongation decrease due to brittle fracture despite a decreasing pore fraction. It is confirmed that the hardness and tensile strength of Ti-5Mo-2Fe P/M improve to more than 360 Hv and 900 MPa, respectively.

The green body of WC-Co cemented carbides containing polymeric binders such as paraffin, polyethylene glycol (PEG), and polyvinyl acetate (PVA) are prepared. The green density of the WC-Co cemented carbides increases with the addition of binders, with the exception of PVA, which is known to be a polar polymeric substance. The green strength of the WC-Co cemented carbides improves with the addition of paraffin and a mixture of PEG400 and PEG4000. In contrast, the green strength of the WC-Co does not increase when PEG400 and PEG4000 is added individually. The compressive strength of the green body increases to 14 MPa, and the machinability of the green body improves when more than 4–6 wt% paraffin and a mixture of PEG400 and PEG4000 is used. Simultaneously, the sintered density of WC-Co is as high as 99% relative density, similar to a low binder addition of 1–2 wt%.

A Cu-15Ag-5P filler metal (BCuP-5) is fabricated on a Ag substrate using a high-velocity oxygen fuel (HVOF) thermal spray process, followed by post-heat treatment (300oC for 1 h and 400oC for 1 h) of the HVOF coating layers to control its microstructure and mechanical properties. Additionally, the microstructure and mechanical properties are evaluated according to the post-heat treatment conditions. The porosity of the heat-treated coating layers are significantly reduced to less than half those of the as-sprayed coating layer, and the pore shape changes to a spherical shape. The constituent phases of the coating layers are Cu, Ag, and Cu-Ag-Cu3P eutectic, which is identical to the initial powder feedstock. A more uniform microstructure is obtained as the heat-treatment temperature increases. The hardness of the coating layer is 154.6 Hv (as-sprayed), 161.2 Hv (300oC for 1 h), and 167.0 Hv (400oC for 1 h), which increases with increasing heat-treatment temperature, and is 2.35 times higher than that of the conventional cast alloy. As a result of the pull-out test, loss or separation of the coating layer rarely occurs in the heat-treated coating layer.

This study examines the surface characteristics, electrical conductivity, electromagnetic wave blocking characteristics, infrared (IR) transmittance, stealth function, thermal characteristics, and moisture characteristics of IR thermal imaging cameras. Nylon film (NFi), nylon fabric (NFa), and 5 types of nylon mesh were selected as the base materials for aluminum sputtering, and aluminum sputtering was performed to study IR thermal imaging, color difference, temperature change, and so on, and the relationship with infrared transmittance was assessed. The electrical conductivity was measured and the aluminum-sputtered nylon film demonstrated 25.6kΩ of surface resistance and high electrical conductivity. In addition, the electromagnetic wave shielding characteristics of the sputtering-treated nylon film samples were noticeably increased as a result of aluminum sputtering treatment as measured by the electromagnetic wave blocking characteristics. When NFi and NFa samples with single-sided sputtering were placed on the human body (sputtering layer faced the outside air) and imaged using IR thermographic cameras, the sputtering layer displayed a color similar to the surroundings, showing a stealth effect. Moreover, the tighter the sample density, the better the stealth function. According to the L, a, b measurements, when the sputtering layer of NFi and NFa samples faced the outside air, the value of a was generally high, thereby demonstrating a concealing effect, and the E value was also high at 124.2 and 93.9, revealing a significant difference between the treated and untreated samples. This research may be applicable to various fields, such as the military wear, conductive sensors, electromagnetic wave shielding film, and others.