The growth and employment effects of R&D investment were analyzed according to business size, export value and manufacturing sectors so as to suggest improvement directions for effective industry policies. The effect of R&D investment was considered simultaneously from the two perspectives of growth and employment effect, and the causality analysis was carried out by using a path analysis. The result of the path analysis confirmed significant differences in the growth effect of R&D investment depending on business size. However, the effect of increasing employment was difficult to obtain statistically significant results for any various combinations of business size and export value. This is a mixture of directions for the effects of R&D investment on employment, which could be due to the failure to consider appropriate time lags between investment and effect. Efficiency analysis by industry sectors confirmed significant differences in efficiency depending on business size, but differences depending on export value were difficult to identify. In order to derive improvement policy by industry sector according to business size and export value, the direction of selective support policy and universal support policy was derived for six industry groups by combining the return to scale in the efficiency analysis and R&D concentration. Hirschman-Herfindahl index is used for calculating R&D concentration.

강원지역은 우리나라의 다설지로서 복잡한 지형 때문에 강설량의 공간변동성이 크다. 특히 동풍조건에서 강설이 발생할 시 강설량의 공간적 변동을 예측하기 어렵다. 동풍조건에서는 강원지역 내 위치에 따라 대기환경조건이 다르며 이는 강설의 특성에도 영향을 줄 수 있다. 본 연구에서는 동풍 조건에서 태백산맥의 풍상측과 풍하측에서 강설의 미세 물리적 특성을 서로 비교 분석하였다. 강원지역 내 4개 관측지점을 선정하여 파시벨 수적계로 입자크기분포를 관측하였다. 얻어진 강설입자 크기 분포의 특성을 풍상측과 풍하측간 비교한 결과, 풍상측의 강설입자 크기 분포는 풍하측에 비해 넓은 분포를 가졌고 작은 강설입자의 수도 많았다. 강설입자의 수농도에 비례하는 보편특성수농도와 강설입자의 직경에 비례하는 보편특성직경 둘 다 풍상측에서 상대적으로 큰 값을 보였다. 또한, 얼음수함량과 강설강도 비교에서도 풍상측 지점에서 큰 평균값을 가졌다. 이 결과가 나타난 원인은 태백산맥 산사면에서 공기덩어리의 강제적 상승효과로 풍상측 지점 상공에 새로운 강설입자의 생성이 활발했기 때문으로 추정된다. 또한, 풍상측은 따뜻하고 습한 동풍이 불어오므로 이로 인해 지상기온이 0oC 근처에 머무르며 강한 부착과정이 일어나기 좋은 조건이다.

Tungsten heavy alloys (W–Ni–Fe) play an important role in various industries because of their excellent mechanical properties, such as the excellent hardness of tungsten, low thermal expansion, corrosion resistance of nickel, and ductility of iron. In tungsten heavy alloys, tungsten nanoparticles allow the relatively low-temperature molding of high-melting-point tungsten and can improve densification. In this study, to improve the densification of tungsten heavy alloy, nanoparticles are manufactured by ultrasonic milling of metal oxide. The physical properties of the metal oxide and the solvent viscosity are selected as the main parameters. When the density is low and the Mohs hardness is high, the particle size distribution is relatively high. When the density is high and the Mohs hardness is low, the particle size distribution is relatively low. Additionally, the average particle size tends to decrease with increasing viscosity. Metal oxides prepared by ultrasonic milling in high-viscosity solvent show an average particle size of less than 300 nm based on the dynamic light scattering and scanning electron microscopy analysis. The effects of the physical properties of the metal oxide and the solvent viscosity on the pulverization are analyzed experimentally.

본 연구는 두록종 돼지의 복당 생시체중 형질(복당 생시체중 평균, 복당 생시체중 표준편차)과 산자수 형질(총 산자수, 생존 산자수, 사산두수)의 유전모수를 추정하고 이들 형질간의 상관관계와 개량방안을 알아보기 위해 실시하였다. 분석에는 국립축산과학원에서 2006~2016년 사이에 분만한 두록 모돈 1,081복의 자료를 이용하였다. 분석형질은 복당 생시체중 평균(ABW), 복당 생시체중 표준편차(BWSD), 총 산자수 (NB), 생존 산자수(NBA) 및 사산두수(NBD)이다. 유전모수 추정은 다형질 개체모형을 이용하였다. 각 형질에 대한 유전력은 복당 생시체중 평균(ABW), 복당 생시체중 표준편차(BWSD), 총 산자수(NB), 생존 산자수(NBA) 및 사산두수(NBD)에 대해 각각 0.32, 0.13, 0.11, 0.10, 및 0.06으로 추정되었다. 복당 생시체중 평균(ABW)과 복당 생시체중 표준편차(BWSD)는 0.75의 높은 정의 유전상관을 보인 반면 생존 산자수(NBA)와 복당 생시체중 평균(ABW), 복당 생시체중 표준편차(BWSD)간의 유전상관은 각각 –0.26, -0.40로 생존 산자수(NBA)가 증가함에 따라 복당 생시체중 평균과 복내 개체간 체중의 표준편차는 감소하는 것으로 나타났다. 생존 산자수(NBA)와 사산두수(NBD)간의 유전상관은 0.24로 생존 산자수(NBA)가 증가하면 사산두수(NBD)도 증가하는 유전적 관계를 나타내었다. 한편 복당 생시체중 평균(ABW)과 복당 생시체중 표준편차(BWSD), 사산두수(NBD), 총 산자수(NB)간의 유전상관은 각각 0.75, 0.81과 0.08로 추정되어 복당 생시체중 평균(ABW)이 증가하면 총 산자수(NB)의 큰 변화 없이 복당 생시체중 표준편차(BWSD), 사산두수(NBD)가 증가하는 것으로 나타났다. 본 결과로 미루어 볼 때 유전력이 높은 복당 생시체중 평균(ABW)은 직접선발을 통한 빠른 개량이 가능한 반면 복당 생시체중 표준편차(BWSD), 총 산자수(NB), 생존 산자수(NBA) 및 사산두수(NBD) 형질은 직접선발을 통한 개량 효과가 낮을 것으로 판단된다. 특히 자돈 생시체중의 균일도를 개량하고자 한다면 복당 생시체중 표준 편차(BWSD)에 대한 직접선발 방법과 더불어 복당 생시체중 평균(ABW)을 이용해 간접선발하는 방법 또한 이용 가능할 것으로 사료된다.

The photovoltaic properties of TiO2 used for the electron transport layer in perovskite solar cells(PSCs) are compared according to the particle size. The PSCs are fabricated and prepared by employing 20 nm and 30 nm TiO2 as well as a 1:1 mixture of these particles. To analyze the microstructure and pores of each TiO2 layer, a field emission scanning electron microscope and the Brunauer–Emmett–Teller(BET) method are used. The absorbance and photovoltaic characteristic of the PSC device are examined over time using ultraviolet-visible-near-infrared spectroscopy and a solar simulator. The microstructural analysis shows that the TiO2 shape and layer thicknesses are all similar, and the BET analysis results demonstrate that the size of TiO2 and in surface pore size is very small. The results of the photovoltaic characterization show that the mean absorbance is similar, in a range of about 400-800 nm. However, the device employing 30 nm TiO2 demonstrates the highest energy conversion efficiency(ECE) of 15.07 %. Furthermore, it is determined that all the ECEs decrease over time for the devices employing the respective types of TiO2. Such differences in ECE based on particle size are due to differences in fill factor, which changes because of changes in interfacial resistance during electron movement owing to differences in the TiO2 particle size, which is explained by a one-dimensional model of the electron path through various TiO2 particles.

As a case study on aspect ratio behavior, Kaolin, zeolite, TiO2, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 pai media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D50, ~6 μm are shifted to submicron size, D50 ~0.6 μm, after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.

This study analyzes the mechanical properties, including the attrition rate, of 50 μm size yttria-stabilized zirconia (YSZ) beads with different microstructures and high-energy milling conditions. The yttria distribution in the grain and grainboundary of the fully sintered beads relates closely to Vickers hardness and the attrition rate of the YSZ beads. Grain size, fractured surfaces, and yttrium distribution are analyzed by electronic microscopes. For standardization and a reliable comparison of the attrition rate of zirconia beads with different conditions, Zr content in milled ceramic powder is analyzed and calculated by X-ray Fluorescence Spectrometer(XRF) instead of directly measuring the weight change of milled YSZ beads. The beads with small grain sizes sintered at lower temperature exhibit a higher Vickers hardness and lower attrition rate. The attrition rate of 50 μm YSZ beads is measured and compared with the various materials properties of ceramic powders used for high-energy milling. The attrition rate of beads appears to be closely related to the Vickers hardness of ceramic materials used for milling, and demonstrates more than a 10 times higher attrition rate with Alumina(Hv ~1650) powder than BaTiO3 powder (Hv ~315).

본 연구는 2015-2018년 5월 기간 동안 납자루아과 어류의 서식 집단 중 강원도 홍천 내촌천(HN), 덕치천(HD), 정선 골지천(JG) 및 조양강(JJ)을 대상으로 기 개발된 제한절편 길이 다형성(restriction fragment length polymorphism; RFLP) 분자마커를 이용하여 숙주조개 속 난 및 치어에 대한 정확한 종 동정을 수행 후 납자루아과 어류의 숙주조개 크기에 대한 산란양상을 파악하고자 하였다. 연구대상 지역 내 납자루아과 어류는 내촌천과 골지천에서 1종(묵납자루; Acheilognathus signifer), 덕치천에서 3종(각시붕어; Rhodeus uyekii, 묵납자루; A. signifer, 줄납자루; Acheilognathus yamatsutae), 조양강에서 2종(묵납자루, 줄납자루)으로 확인되었고, 네 지역에서 모두 동서하고 있는 숙주조개인 작은 말조개(Unio douglasiae sinuolatus) 982개체를 채집하였다. RFLP 분자마커를 이용하여 납자루아과 어류의 난 및 치어가 확인된 작은말조개(N=163; 16.6%)에서 총 646개체의 납자루아과 어류의 난 및 치어(묵납자루 454, 줄납자루 43, 각시붕어 149개체)를 확인하였다. 각 지역 숙주조개 크기에 따른 산란선호도를 조사하기 위해 난 및 치어가 확인된 숙주조개(mussels with [presence] eggs/fry)와 확인되지 않은 숙주조개(mussels without [absence] eggs/fry)의 각장 (shell length), 각고(shell height) 및 각폭(shell width)의 평균 크기를 비교하였다. 그 결과 3종의 납자루아과 어류가 동서하는 덕치천의 경우 난 및 치어가 확인된 숙주조개가 확인되지 않은 숙주조개보다 각장(1.98mm), 각고(0.85mm), 각폭(0.73mm)의 크기가 통계적으로 유의하게 크게 나타났으며(Mann-Whitney U tests, P=0.002, P=0.012, P=0.009), 다른 세 개의 지역에서도 난 및 치어가 확인된 조개의 각장, 각고, 각폭의 크기가 큰 결과를 보였으나, 통계적으로 유의하지는 않았다. 추가적으로 종 간 숙주조개 당 평균산란 난 및 치어의 수를 분석한 결과 각시붕어 9.31±5.94개, 묵납자루 2.86±2.45개, 줄납자루 2.50±1.32개로 각시붕어는 묵납자루와 줄납자루보다 숙주조개 당 평균 6.45~6.81개 더 많이 산란하였고, 통계적으로 유의한 결과를 나타내었다(Kruskal-Wallis test, P<0.001). 이 결과는 본 연구 대상 납자루아과 어류 3종에서 크기가 큰 작은말조개를 산란을 위한 숙주로서 선호함을 의미하고, 조개 크기에 대한 선호도 차이가 동서하는 납자루아과 종의 수가 많을수록 크게 나타났다. 또한, 묵납자루와 줄납자루의 경우 많은 숙주조개에 적은 양의 난을 추가적으로 고르게 산란하는 반면에 각시붕어는 비교적 적은 수의 숙주조개에 많은 양의 난을 산란하는 번식전략을 나타내었다. 2종 이상의 납자루아과 어류가 서식하는 덕치천(HD)과 조양강(JJ)에서 묵납자루와 줄납자루 2종이 동일한 조개에 산란하는 것이 관찰되었다(N=4). 이는 납자루아과 어류가 2종 이상 동서할 때, 동일한 자원인 작은말조개를 자신의 산란숙주로 이용하기 위한 종간경쟁(interspecific competition)이 일어나고 있는 것으로 판단된다. 본 연구에서는 기존 연구된 생태학적 연구에 유전학적인 방법을 추가하여 각 집단 간, 종 간 숙주조개 크기에 대한 산란양상을 보다 정확히 규명하여 숙주조개를 이용하는 납자루아과 어류의 생태적 적응양상을 명확히 파악하고 더 나아가 숙주조개와 납자루아과 어류의 공생(mutualism) 혹은 숙주-기생의 상호관계(host-parasite relationship)를 규명 하는데 기여할 수 있을 것으로 기대한다.

PURPOSES : In Korea, asphalt overlay has been used as a typical alternative rehabilitation method for deteriorated pavements. However, asphalt overlay has problems due to poor bonding of the asphalt overlay and the old concrete. Recently, concrete overlays, which have advantages such as long-term durability and high structural capacity to carry heavy traffic, have been considered for rehabilitation construction. However, concrete overlays have limitations such as difficulty in opening to traffic and pavement noise. Recently, an appropriate fine-size exposed aggregate concrete pavement technique was reported to solve these problems. Therefore, this study aims to suggest an optimum mixture design of fine-size exposed aggregate concrete overlay (EACO) that can ensure low noise and early strength. METHODS : The optimum mixture design of fine-size EACO is determined to ensure adequate structural performance for early traffic opening and good functional performances such as low noise. Therefore, the optimum mixture proportion is determined based on the optimum design of aggregate content to produce a low-noise pavement texture by controlling the exposed aggregate number (EAN) and mean texture depth (MTD). RESULTS : The water-cement ratio and unit cement ratio were used to determine the mixture designs to achieve workability and adequate strength for early traffic opening. The texture was determined by selecting the maximum size of coarse aggregate smaller than 10 mm with an S/a ratio of less than 30% for low noise. With these mixture proportions, the EAN and MTD were 50±5 / 25cm2 and 1.0±0.2 mm. Respectively, which meet the criteria for EACO. CONCLUSIONS: In this study, an optimum mixture design of EACO for early traffic opening and low noise is suggested by using earlyhigh strength cement, and the pavement texture is implemented considering EAN and MTD. In addition, a pavement surface texture criterion is suggested for the quality control of EACO.

We investigated the effects of honey bee (Apis mellifera L.) colony size on the pollination of greenhouse-cultivated watermelon grown under the forcing cultivation system. The highest pollination activity of bees was observed (14.3 ± 5.0 honey bees/day) when the bee colony size was 10,000 honey bees, followed by 7,500 and 5,000 honey bees. There was a positive correlation between the bee colony size and pollination activity (R = 0.262). There was no significant difference in the fruit set with different honey bee colony sizes (88%–91%). However, the larger the bee colony size, the higher the number of seeds fertilized and the rate of seed fertilization (p > 0.05). The number of seeds and the content of sugar were negatively correlated (R = -0.714). Overall, we found that a colony size of 5,000 honey bees was the most effective for the pollination of watermelon grown under forcing cultivation.

Three ambrosia beetle species, Xyleborus glabratus, Monarthrum mali, and Euwallacea fornicatus belong to subfamily, Scolytinae, showing similar morphology and body size, but their flight capability and patterns showed species-specific. Body length of Xyleborus glabratus and Monarthrum mali was negatively correlated with flight capabilities; shorter beetles performed longer average flights, longer single flights, total flight distance, and total flight time. Elytral length also was negatively correlated with flight distance in X. glabratus and M. mali. Conversely, only average flight time of E. fornicatus was positively correlated with body length, pronotal width, and elytral length. Body length had no effect on the flight velocity of any of the three beetle species examined. Therefore, our results indicate that body size characteristics of ambrosia beetles differentially influence on their dispersal by species.

This study is about the process capability index (PCI). In this study, we introduce several indices including the index CPR and present the characteristics of the CPR as well as its validity. The difference between the other indices and the CPR is the way we use to estimate the standard deviation. Calculating the index, most indices use sample standard deviation while the index CPR uses range R. The sample standard deviation is generally a better estimator than the range R . But in the case of the panel process, the CPR has more consistency than the other indices at the point of non-conforming ratio which is an important term in quality control. The reason why the CPR using the range has better consistency is explained by introducing the concept of ‘flatness ratio’. At least one million cells are present in one panel, so we can’t inspect all of them. In estimating the PCI, it is necessary to consider the inspection cost together with the consistency. Even though we want smaller sample size at the point of inspection cost, the small sample size makes the PCI unreliable. There is ‘trade off’ between the inspection cost and the accuracy of the PCI. Therefore, we should obtain as large a sample size as possible under the allowed inspection cost. In order for CPR to be used throughout the industry, it is necessary to analyze the characteristics of the CPR . Because the CPR is a kind of index including subgroup concept, the analysis should be done at the point of sample size of the subgroup. We present numerical analysis results of CPR by the data from the random number generating method. In this study, we also show the difference between the CPR using the range and the CP which is a representative index using the sample standard deviation. Regression analysis was used for the numerical analysis of the sample data. In addition, residual analysis and equal variance analysis was also conducted.

This paper develops an algorithm to determine the batch size of the batch process in real time for improving production and efficient control of production system with multiple processes and batch processes. It is so important to find the batch size of the batch process, because the variability arising from the batch process in the production system affects the capacity of the production. Specifically, batch size could change system efficiency such as throughput, WIP (Work In Process) in production system, batch formation time and so on. In order to improve the system variability and productivity, real time batch size determined by considering the preparation time and batch formation time according to the number of operation of the batch process. The purpose of the study is to control the WIP by applying CONWIP production system method in the production line and implements an algorithm for a real time batch size decision in a batch process that requires long work preparation time and affects system efficiency. In order to verify the efficiency of the developed algorithm that determine the batch size in a real time, an existed production system with fixed the batch size will be implemented first and determines that batch size in real time considering WIP in queue and average lead time in the current system. To comparing the efficiency of a system with a fixed batch size and a system that determines a batch size in real time, the results are analyzed using three evaluation indexes of lead time, throughput, and average WIP of the queue.

주입구멍의 크기와 수관 상태에 따른 약액의 수간주입 속도를 알아보고자 주입구멍의 지름을 5mm와 10mm로 하고 수관을 온전, 절반 제거, 1/4씩 두 곳 제거 등 세 수준으로 구분하여 식용색소 적색3호 수용액을 수간주입하고 일정 시간별로 주입량을 측정하였다. 수간주입 4시간 뒤에 대부분의 느티나무에서 약액이 30% 이상 흡수된 상태였으며, 7시간 후에서는 7그루에서 모든 약액이 흡수된 것을 확인하였다. 48시간 후에는 처리 조건과 방법에 관계없이 한 그루를 제외한 모든 개체에서 주입액이 완전흡수되었다. 주입구멍의 크기나 수관의 상태 등은 수간주입 속도와 통계적 유의성이 없었다. 주간에서 움트는 잔가지의 잎들은 수간주입 후 24시간에 붉은색을 나타내기 시작하였으며, 48시간 후에는 수관의 잎들도 엽육조직이 붉게 변하여 수관도 붉은 색을 보였다. 수관이 변색된 나무의 수도 처리 내용 간에 통계적 유의차가 없었다. 줄기 단면 관찰에서도 주입구멍의 크기나 수관 상태 간에 적색주입액의 분포 차이가 없었다. 본 연구의 결과로부터 주입구멍의 크기나 수관의 엽량은 수간주입의 효율에 영향을 미치지 않음이 확인되었다. 따라서 큰 상처를 남기는 지름 10mm 주입구멍보다는 지름 5mm 주입구멍을 사용 하는 것이 나무의 자가치유를 도와주는 올바른 수간주입법이라고 할 수 있다.

For the vessel export of strawberries, modified atmosphere package (MAP) using polyamide (PA) film and linear low density polyethylene (LLDPE) film was investigated to extend the shelf life of strawberries. Because the temperature and relative humidity changes of the MAP were lower than the changes of the control, the weight loss of the MAP were lower than that of the control. The low oxygen level and high carbon dioxide level were effective to decrease the fungal decay rate and to increase the hardness of strawberries. The Hunter’s color differences before and after storage showed no distinct difference between the MAP and the control. The lightness had a tendency to decrease while the redness increased. There were no significant changes of the soluble solids during the storage. The shelf life of strawberries could be extended to 16 days using the MAP considering the weight loss and the fungal decay rate. Thus, this MAP method using PA film and LLDPE film was effective to extend the shelf life of strawberries.

PURPOSES : Exposed aggregate concrete pavements have been adopted in several countries because of their advantages of pavement texture characteristics, which can produce low tire-pavement noise and higher load-carrying capacities. The magnitude of tire-pavement noise greatly depends on the wavelength of pavement texture. The wavelength of exposed aggregate concrete pavement can be controlled with maximum sizing and by controlling the amount of coarse aggregates in the concrete mixture. In this study, the maximum size and the amount of coarse aggregate in the exposed aggregate concrete pavement are investigated to produce equal levels of wavelength in the asphalt pavement. METHODS: A simple method to measure the average wavelength of pavement texture is introduced. Subsequently, the average wavelength of typical asphalt pavement is investigated. A set of mixture designs of exposed aggregate concrete with three maximum-sized coarse aggregates, and three amounts of coarse aggregate are used. The average wavelengths are measured to find the mixture design needed to produce equal levels of wavelength as typical asphalt pavement. RESULTS : With a cement content of 420 kg/m3 and fine aggregate modulus of 30%, the number of exposed aggregates was 48, and the shortest texture depth provided a wavelength of 4.2 mm. According to the number of exposed aggregates, the exposed aggregate concrete pavement could be rendered low-noise, because its wavelength was similar to that of asphalt pavement ranging from 3.9 to 4.4 mm. CONCLUSIONS : Selection of appropriate maximum sizes and the amount of coarse aggregates for exposed aggregate concrete pavement can produce a wavelength texture closely resembling that of asphalt pavement. Therefore, the noise level of exposed aggregate concrete pavement can be reduced with an appropriate maximum size and the amount of coarse aggregates are employed.

In this study, the effects of powder size and composition on the reflectance of Al-Si based alloys are presented. First, the reflectance of Al-Si bulk and powder are analyzed to confirm the effect of powder size. Results show that the bulk has a higher reflectance than that of powder because the bulk has lower surface defects. In addition, the larger the particle size, the higher is the reflectance because the interparticle space decreases. Second, the effect of composition on the reflectance by the changing composition of Al-Si-Mg is confirmed. Consequently, the reflectance of the alloy decreases with the addition of Si and Mg because dendrite Si and Mg2Si are formed, and these have lower reflectance than pure Al. Finally, the reflectance of the alloy is due to the scattering of free electrons, which is closely related to electrical conductivity. Measurements of the electrical conductivity based on the composition of the Al-Si-Mg alloy confirm the same tendency as the reflectance.

In this study, a high speed Rigid Inflatable Boat(RIB) with about 10 meters length is developed. Design speed of the boat is 30 knots (15.43 m/s) using 250 hp twin engines and main material is aluminum. Resistance performance related to the free running attitude as trim and sinkage are discussed and wave patterns are observed to make clear the relationship between the performance and wave characteristics using model test and CFD analysis. The results show that not only wave patterns but also free running attitude of the boat have a strong influence on resistance performance. CFD results including free surface give good relative tendency for effective power and the attitude comparing model test results. CFD analysis used in this study can be used at initial ship design stage of high speed boat.