The purpose of development new variety ‘Miho’ (Hordeum vulgare L.) is a favorite with livestock feed and develop varieties resistant to disease and lodging. ‘Miho’ was carrying out the growth habit of group Ⅲ with green and mid-wide leaf. Awn that is related to preference of livestock is a semi-smooth awn. This cultivar had 96 cm of culm length, 650 of spikes per m2. Heading date of ‘Miho’ was April 27, and maturing date on May 30, which were later than cultivar ‘Youngyang’. It also showed strong winter hardiness, and similar resistance to shattering and bariy yellow mosaic virus (BaYMV) compared with those of check one. The best thing among the traits of a good quality with the plant green at the latter growing period. The average forage dry matter yield in the regional yield trial was about 13.1, 12.1 MT per ha in upland and paddy field, respectively, which were 9%, 2% higher than that of the check cultivar. It’s also showed 6.8% crude protein, 27.1% ADF (acid detergent fiber), and 67.5% TDN (total digestible nutrients), including higher silage quality for whole crop barley. This cultivar would be suitable for the area whose average minimum temperature was above －8℃ January in Korean peninsula.

Cu-30 vol% SiC composites with relatively densified microstructure and a sound interface between the Cu and SiC phases were obtained by pressureless sintering of PCS-coated SiC and Cu powders. The coated SiC powders were prepared by thermal curing and pyrolysis of PCS. Thermal curing at 200 oC was performed to fabricate infusible materials prior to pyrolysis. The cured powders were heated treated up to 1600 oC for the pyrolysis process and for the formation of SiC crystals on the surface of the SiC powders. XRD analysis revealed that the main peaks corresponded to the α-SiC phase; peaks for β-SiC were newly appeared. The formation of β-SiC is explained by the transformation of thermally-cured PCS on the surface of the initial α-SiC powders. Using powder mixtures of coated SiC powder, hydrogen-reduced Cu-nitrate, and elemental Cu powders, Cu-SiC composites were fabricated by pressureless sintering at 1000 oC. Microstructural observation for the sintered composites showed that the powder mixture of PCS-coated SiC and Cu exhibited a relatively dense and homogeneous microstructure. Conversely, large pores and separated interfaces between Cu and SiC were observed in the sintered composite using uncoated SiC powders. These results suggest that Cu-SiC composites with sound microstructure can be prepared using a PCS coated SiC powder mixture.

Microstructural examination of the Nb-Si-B alloys at Nb-rich compositions is performed. The Nb-rich corner of the Nb-Si-B system is favorable in that the constituent phases are Nb (ductile and tough phase with high melting temperature) and T2 phase (very hard intermetallic compound with favorable oxidation resistance) which are good combination for high temperature structural materials. The samples containing compositions near Nb-rich corner of the Nb- Si-B ternary system are prepared by spark plasma sintering (SPS) process using T2 and Nb powders. T2 bulk phase is made in arc furnace by melting the Nb slug and the Si-B powder compact. The T2 bulk phase was subsequently ballmilled to powders. SPS is performed at 1300oC and 1400oC, depending on the composition, under 30 MPa for 600s, to produce disc-shaped specimen with 15 mm in diameter and 3 mm high. Hardness tests (Rockwell A-scale and micro Vickers) are carried out to estimate the mechanical property.

본 연구는 국내 보리 재배시 보리그물무늬병 감염정도를 조사하여 지역과 연차간 종자 전염 발생 변 화와 기상 요인의 상관관계를 확인하기 위하여 수행하였다. 병징은 3월 5일부터 잎에 흑갈색의 작은 반 점들로부터 시작되어 보리의 출수기경에는 잎 전체가 고사되는 증상을 보였다. 감염 종자는 약한 붉은 색의 종피 변색을 나타내었다. 2조와 6조 겉보리 19품종을 시험한 결과 지역에 따라 종자 감염률이 차 이를 보였는데 평균 종자 감염률은 김제와 익산에서 각각 0.09-1.36%와 1.44-2.81%로 익산 지역에서 높은 것으로 조사되었다. 또한, 6조 겉보리가 2조에 비해 병 감염에 의한 종자 감염률에 대해 저항성이 큰 것으로 나타났으며 보리그물무늬병에 의한 연차간 종자감염률의 변화를 보였다. 두 맥종에서 2012년 도에는 0.2%와 0.8%를 보였으나, 2013년도에는 1.4%와 2.8%로 높은 발생을 보였다. 이들 연차간 종자 감염률의 차이에 대한 평균기온과 강수량을 비교하였을때, 평균기온은 병 발생이 많았던 2013년도에 2012년에 비해 저온으로 경과하는 양상이었다. 강수량을 비교한 결과 2013년도에 2012년도에 비해 약 120mm 이상의 많은 강수량을 보였다. 이 결과에서 보리 신장기에서 등숙기까지 저온과 높은 강우시 병 발생에 크게 영향을 미치는 것으로 나타났다.

In this study, ternary compound Max Phase Ti2AlC material was mixed by 3D ball milling as a function of ball milling time. More than 99.5 wt% pure Ti2AlC was synthesized by using spark plasma sintering method at 1000, 1100, 1200, and 1300oC for 60 min. The material characteristics of synthesized samples were examined with relative density, hardness, and electrical conductivity as a function of sintering temperature. The phase composition of bulk was identified by X-ray diffraction. On the basis of FE-SEM result, a terraced structures which consists of several laminated layers were observed. And Ti2AlC bulk material obtained a vickers hardness of 5.1 GPa at the sintering temperature of 1100oC.

SKD11 (ASTM D2) tool steel is a versatile high-carbon, high-chromium, air-hardening tool steel that is characterized by a relatively high attainable hardness and numerous, large, chromium rich alloy carbide in the microstructure. SKD11 tool steel provides an effective combination of wear resistance and toughness, tool performance, price, and a wide variety of product forms. Adding of CNTs increased the performance of mechanical properties more. 1, 3 vol% CNTs was dispersed in SKD11 matrix by mechanical alloying. SKD11 carbon nanocomposite powder was sintered by spark plasma sintering process. FE-SEM, HR-TEM and Raman analysis were carried out for the SKD11 carbon nanocomposites.

이 연구는 비닐겹수 및 저장기간 따른 청보리 사일리지 의 사료가치 및 사일리지 품질특성을 구명하고자 수행하였 다. 조단백질 함량은 저장기간 모두 사일리지 제조 전에 비해 높아지는 경향을 보였고, 저장기간이 길어질수록 약 간 높은 값을 보였지만 통계적인 유의성은 없었다. 비닐겹 수에 따라서는 6겹 처리한 처리구가 4겹보다 높은 경향이 었다. NDF와 ADF 함량은 저장기간 모두 사일리지 제조 전보다 높은 경향을 보였고(p<0.05), 저장기간에 따라서는 비슷한 값을 나타냈다. 비닐 겹수에 따라서는 6겹 처리한 처리구가 4겹보다 더 높은 값을 나타냈다. TDN 함량은 저 장기간 모두 사일리지 제조 전보다 낮은 경향을 보였고, 저장기간에 따라서는 비슷한 값을 보였다. 비닐겹수에 따 라서는 6겹에서 다소 낮은 값을 보였다. pH는 저장기간이 길어짐에 따라 낮아지는 경향을 보였고, 비닐겹수에 따라 서는 6겹에서 4겹보다 낮은 값을 보였다. 유기산 함량에서 는 저장기간이 길어짐에 따라 젖산함량은 약간 증가하는 경향을 보였고, 초산함량은 낮아지는 경향을 보였으며 낙 산함량은 유의적으로 증가하는 경향을 보였다(p<0.05). 비 닐겹수에 따라서는 6겹에서 4겹보다 높은 젖산함량과 낮은 낙산함량을 보였다(p<0.05). 따라서 청보리 사일리지는 장 기저장을 할 경우에는 6겹으로 하는 것이 유리하고, 4겹으 로 처리했을 경우 6개월 안에 사용하는 것이 유리하다고 판단된다.

이 연구는 비닐겹수 및 저장기간 따른 청보리 사일리지의 사료가치 및 사일리지 품질특성을 구명하고자 수행하였다. 조단백질 함량은 저장기간 모두 사일리지 제조 전에 비해 높아지는 경향을 보였고, 저장기간이 길어질수록 약간 높은 값을 보였지만 통계적인 유의성은 없었다. 비닐겹수에 따라서는 6겹 처리한 처리구가 4겹보다 높은 경향이었다. NDF와 ADF 함량은 저장기간 모두 사일리지 제조 전보다 높은 경향을 보였고(p<0.05), 저장기간에 따라서는 비슷한 값을 나타냈다. 비닐 겹수에 따라서는 6겹 처리한 처리구가 4겹보다 더 높은 값을 나타냈다. TDN 함량은 저장기간 모두 사일리지 제조 전보다 낮은 경향을 보였고, 저장기간에 따라서는 비슷한 값을 보였다. 비닐겹수에 따라서는 6겹에서 다소 낮은 값을 보였다. pH는 저장기간이 길어짐에 따라 낮아지는 경향을 보였고, 비닐겹수에 따라서는 6겹에서 4겹보다 낮은 값을 보였다. 유기산 함량에서는 저장기간이 길어짐에 따라 젖산함량은 약간 증가하는 경향을 보였고, 초산함량은 낮아지는 경향을 보였으며 낙산함량은 유의적으로 증가하는 경향을 보였다(p<0.05). 비닐겹수에 따라서는 6겹에서 4겹보다 높은 젖산함량과 낮은 낙산함량을 보였다(p<0.05). 따라서 청보리 사일리지는 장기저장을 할 경우에는 6겹으로 하는 것이 유리하고, 4겹으로 처리했을 경우 6개월 안에 사용하는 것이 유리하다고 판단된다.

Ti₂AlN composites are a laminated compounds that posses unique combination of typical ceramic proper- ties and typical metallic(Ti alloy) properties. In this paper, the powder synthesis, SPS sintering, composite characteristics and machinability evaluation were systematically conducted. The random orientation characteristics and good crystalli- zation of the Ti2AlN phase are observed. The electrical and thermal conductivity of Ti2AlN is higher than that of Ti6242 alloy. A machining test was carried out to compare the effect of material properties on micro electrical discharge drilling for Ti2AlN composite and Ti6242 alloy. Also, mixture table as a kind of tables of orthogonal arrays was used to know how parameter is main effective at experimental design. Consequently, hybrid Ti2AlN ceramic composites showed good machining time and electrode wear shape under micro ED-drilling process. This conclusion proves the feasibility in the industrial applications.

Ru films were successfully prepared by plasma-enhanced atomic layer deposition (PEALD) using and plasma. To optimize Ru PEALD process, the effect of growth temperature, plasma power and plasma time on the growth rate and preferred orientation of the deposited film was systemically investigated. At a growth temperature of and plasma power of 100W, the saturated growth rate of 0.038 nm/cycle was obtained on the flat /Si substrate when the and plasma time was 7 and 10 sec, respectively. When the growth temperature was decreased, however, an increased plasma time was required to obtain a saturated growth rate of 0.038 nm/cycle. Also, plasma power higher than 40 W was required to obtain a saturated growth rate of 0.038 nm/cycle even at a growth temperature of . However, (002) preferred orientation of Ru film was only observed at higher plasma power than 100W. Moreover, the saturation condition obtained on the flat /Si substrate resulted in poor step coverage of Ru on the trench pattern with an aspect ratio of 8:1, and longer plasma time improved the step coverage.

본 연구에서는 1000 hPa면 고도 자료 및 K-평균 군집분석법을 활용하여 한반도 주변 기압배치를 분류하고, 각 유형의 특성을 조사하였다. 군집의 기준으로 기압배치 공간 형태의 유사성을 나타내는 패턴 상관계수를 사용하고, 유사성의 경계치로 0.8을 적용하여 대표적 기압배치 유형 11개를 얻었다. 이들은 시베리아 기단이 한반도 주변으로 장출하는 경로에 따라 3개, 북태평양 고기압의 중심 위치에 따라 3개, 시베리아 및 북태평양 기단의 영향권에서 기압골이 나타나는 유형 2개, 그리고 봄가을에 주로 나타나는 이동성 고기압형으로 고기압의 장축방향에 따라 3개 등이다. 각 기압 배치 유형의 출현빈도로부터 추정한 한반도에 영향을 주는 기단의 출현비율은 시베리아 기단 55.4%, 북태평양 기단 29.3%, 양쯔강 기단 12.8%, 오호츠크해 기단 2.5% 순이며, 한반도는 대륙에서 기원한 기단의 영향이 68.2%로 지배적이다. 한반도 주변 기압계는 겨울 기압배치 유형과 여름 기압배치 유형이 각기 대륙과 해양에 발달하는 정체성 기단으로부터 확장되는 고기압을 중심으로 하여 대조적으로 출현하고, 봄가을의 이동성 고기압형은 이들의 변환 과정에서 나타난다. 근래 여름 북태평양 고기압의 한반도 출현빈도가 감소하고 있다. 그리고 겨울 기압배치 유형의 출현이 봄가을에 자주 나타나면서 기압골을 갖는 기압배치 유형의 출현빈도가 증가하고, 이동성 고기압형은 거의 모든 계절에 나타나는 경향이 있다.

Bismuth antimony telluride (BiSbTe) thermoelectric materials were successfully prepared by a spark plasma sintering process. Crystalline BiSbTe ingots were crushed into small pieces and then attrition milled into fine powders of about 300 nm ~ 2μm size under argon gas. Spark plasma sintering was applied on the BiSbTe powders at 240, 320, and 380˚C, respectively, under a pressure of 40 MPa in vacuum. The heating rate was 50˚C/min and the holding time at the sintering temperature was 10 min. At all sintering temperatures, high density bulk BiSbTe was successfully obtained. The XRD patterns verify that all samples were well matched with the Bi0.5Sb1.5Te3. Seebeck coefficient (S), electric conductivity (σ) and thermal conductivity (k) were evaluated in a temperature range of 25~300˚C. The thermoelectric properties of BiSbTe were evaluated by the thermoelectric figure of merit, ZT (ZT = S2σT/k). The grain size and electric conductivity of sintered BiSbTe increased as the sintering temperature increased but the thermal conductivity was similar at all sintering temperatures. Grain growth reduced the carrier concentration, because grain growth reduced the grain boundaries, which serve as acceptors. Meanwhile, the carrier mobility was greatly increased and the electric conductivity was also improved. Consequentially, the grains grew with increasing sintering temperature and the figure of merit was improved.

The hybrid structured photo-electrode for dye-sensitized solar cells was fabricated based on the composites of nanoparticles and nanowires. Three samples with different hybrid structures were prepared with 17 vol%, 43 vol%, and 100 vol% nanowires. The energy conversion efficiency was enhanced from 5.54% for pure nanoparticle cells to 6.01% for the hybrid structure with 17 vol% nanowires. For the hybrid structured layers with high nanowires concentration (43 vol% and 100 vol%), the efficiency decreased with the nanowire concentration, because of the decrease of specific surface area, and of thus decreased current density. The random orientations of nanowires can be preserved by the doctor blade process, resulted in the enhanced efficiency. The hybrid structured layer can possess the advantages of the high surface area of nanoparticles and the rapid electron transport rate and the light scattering effect of nanowires.

In this paper, the effect of electrical characteristics and electrode shape on the alignment and attachment of multi-walled carbon nanotubes (MWNTs) has been studied. The attraction and alignment of MWNTs between the gaps has been investigated by applying electric field which is called electrophoresis and dielectrophoresis. According to the frequency of electric field, positive or negative dielectrophoretic force can be determined. The concentration of MWNTs solution was , and a droplet of was dropped between two electrodes. Through the repeated experiments, the optimal electrical conditions for aligning and attaching MWNTs in the desired places were obtained. Since the frequency range of 100 kHz~10 MHz generated positive dielectrophoretic force, MWNTs were attracted and aligned between the gaps with this frequency range. For generating enough force to attract MWNTs, the appropriate voltage range was . Furthermore, the effect of electrode shape on the alignment of MWNTs was investigated. A single MWNT attachment was accomplished on the round shaped with 70% yield.

Electrical discharge machining (EDM) is an attractive machining technique but it requires electrically conductive ceramic materials. In this study, Alumina matrix composites reinforced with CNTs were fabricated through CNT purification, mixing, compaction and spark plasma sintering (SPS) processes. nanocomposites with the different CNT concentrations were synthesized. The mechanical and electrical characteristics of /CNTs composites were examined in order to apply the materials to the EDM process. In addition, micro-EDM using wire electrical discharge grinding (WEDG) was conducted under the various EDM parameters to investigate the machining characteristics of machined hole by Field Emission Scanning Electron Microscope (FE-SEM). The results show that /CNTs 10%Vol. was more suitable than the other materials because high conductivity and large discharge energy caused violent sparks resulting in bad machining accuracy and surface quality.

In this paper, experimental studies of the regrinding of tungsten carbide (WC-Co) tools for high-speed machining were conducted. Regrinding and a subsequent evaluation test were carried out for a flat endmill tool with diameters of 10 mm and 3 mm using a CNC five-axis tool grinder and a CNC three-axis machining center. Tool wear on the two types of endmill tools increased as the cutting length increased, and the tool wear was not influenced by the regrinding state. In case of the micro endmill with a tool diameter of 3 mm, the effective regrinding time was determined for a flank wear threshold of 0.3 mm considering the tool life according to cutting length. The tool lives of the 10 mm and 3 mm endmill tools were increased by 80% and 72%, respectively. This conclusion proves the Feasibility of the recycling of tungsten carbide materials in the high-speed machining of high-hardened materials for industrial applications.

To satisfy the demand of higher cutting performance, mechanical properties with tungsten carbide (WC-Co) tool materials were investigated. Hardness and transverse rupture strength with WC grain size, Co content and density were measured. Compared to H, K, and S manufacture maker as tungsten carbide (WC-Co) tool materials were used for high-speed machining of end-milling operation. The three tungsten carbide (WC-Co) tool materials were evaluated by cutting of STD 11 cold-worked die steel (HRC25) under high-speed cutting condition. Also, tool life was obtained from measuring flank wear by CCD wear measuring system. Tool dynamometer was used to measure cutting force. The cutting force and tool wear are discussed along with tool material characteristics. Consequently, the end-mill of K, H manufacture maker showed higher wear-resistance due to its higher hardness, while the S maker endmill tool showed better performance for high metal removal.

The microstructure and mechanical properties of hot-pressed composites with a different sintering temperature have been studied. The size of matrix grain and Cu dispersion in composites increased with increase in sintering temperature. Fracture toughness of the composite sintered at high temperature exhibited an enhanced value. The toughness increase was explained by the thermal residual stress, crack bridging and crack branching by the formation of microcrack. The nanocomposite, hot-pressed at , showed the maximum fracture strength of 707 MPa. The strengthening was mainly attributed to the refinement of matrix grains and the increased toughness.