In this study, three kinds of bainitic steels are fabricated by controlling the contents of vanadium and boron. High vanadium steel has a lot of carbides and nitrides, and so, during the cooling process, acicular ferrite is well formed. Carbides and nitrides develop fine grains by inhibiting grain growth. As a result, the low temperature Charpy absorbed energy of high vanadium steel is higher than that of low vanadium steel. In boron added steel, boron segregates at the prior austenite grain boundary, so that acicular ferrite formation occurs well during the cooling process. However, the granular bainite packet size of the boron added steel is larger than that of high vanadium steel because boron cannot effectively suppress grain growth. Therefore, the low temperature Charpy absorbed energy of the boron added steel is lower than that of the low vanadium steel. HAZ (heat affected zone) microstructure formation affects not only vanadium and boron but also the prior austenite grain size. In the HAZ specimen having large prior austenite grain size, acicular ferrite is formed inside the austenite, and granular bainite, bainitic ferrite, and martensite are also formed in a complex, resulting in a mixed acicular ferrite region with a high volume fraction. On the other hand, in the HAZ specimen having small prior austenite grain size, the volume fraction of the mixed acicular ferrite region is low because granular bainite and bainitic ferrite are coarse due to the large number of prior austenite grain boundaries.

In this study, the effects of Co content on the microstructure and Charpy impact properties of Fe-Cr-W ferritic/martensitic oxide dispersion strengthened (F/M ODS) steels are investigated. F/M ODS steels with 0–5 wt% Co are fabricated by mechanical alloying, followed by hot isostatic pressing, hot-rolling, and normalizing/tempering heat treatment. All the steels commonly exhibit two-phase microstructures consisting of ferrite and tempered martensite. The volume fraction of ferrite increases with the increase in the Co content, since the Co element considerably lowers the hardenability of the F/M ODS steel. Despite the lowest volume fraction of tempered martensite, the F/M ODS steel with 5 wt% Co shows the highest micro-Vickers hardness, owing to the solid solution-hardening effect of the alloyed Co. The high hardness of the steel improves the resistance to fracture initiation, thereby resulting in the enhanced fracture initiation energy in a Charpy impact test at – 40oC. Furthermore, the addition of Co suppresses the formation of coarse oxide inclusions in the F/M ODS steel, while simultaneously providing a high resistance to fracture propagation. Owing to these combined effects of Co, the Charpy impact energy of the F/M ODS steel increases gradually with the increase in the Co content.

In this study, the effect of tempering on the stretch-flangeability is investigated in 980 MPa grade dual-phase steel consisting of ferrite and martensite phases. During tempering at 300 oC, the strength of ferrite increases due to the pinning of dislocations by carbon atoms released from martensite, while martensite is softened as a consequence of a reduction in its carbon super-saturation. This strength variation results in a considerable increase in yield strength of the steel, without loss of tensile strength. The hole expansion test shows that steel tempered for 20 min (T20 steel) exhibits a higher hole expansion ratio than that of steel without tempering (T0 steel). In T0 steel, severe plastic localization in ferrite causes easy pore formation at the ferrite-martensite interface and subsequent brittle crack propagation through the highly deformed ferrite area during hole expansion testing; this propagation is mainly attributed to the large difference in hardness between ferrite and martensite. When the difference in hardness is not so large (T20 steel), on the other hand, tempered martensite can be considerably deformed together with ferrite, thereby delaying pore formation and hindering crack propagation by crack blunting. Eventually, these different deformation and fracture behaviors contribute to the superior stretch-flangeability of T20 steel.

In this study, effects of carbon and nickel on microstructure and low temperature Charpy impact properties of HSLA (high strength low alloy) steels are investigated. To understand the complex phase transformation behavior of HSLA steels with high strength and toughness before and after welding processes, three kinds of HSLA steels are fabricated by varying the carbon and nickel content. Microstructure analysis, low temperature Charpy impact test, and Vickers hardness test are performed for the base metals and CGHAZ (coarse-grain heat affected zone) specimens. The specimens with the lowest carbon and nickel content have the highest volume fraction of AF, the lowest volume fraction of GB, and the smallest GB packet size. So, the low temperature Charpy absorbed energy of the CGHAZ specimen is the highest. The specimens with increased carbon and nickel content have the lowest volume fraction of AF, the highest volume fraction of GB, and the largest GB packet size. So, the low temperature Charpy absorbed energy of the CGHAZ specimen is the lowest.

Fluorescent nanoparticles are characterized by their unique properties such as luminescence, optical transparency, and sensitivity to various chemical environments. For example, semiconductor nanocrystals (quantum dots), which are nanophosphors doped with transition metal or rare earth ions, can be classified as fluorescent nanoparticles. Tuning their optical and physico-chemical properties can be carried out by considering and taking advantage of nanoscale effects. For instance, quantum confinement causes a much higher fluorescence with nanoparticles than with their bulk counterparts. Recently, various types of fluorescent nanoparticles have been synthesized to extend their applications to other fields. In this study, State-of-the-art fluorescent nanoparticles are reviewed with emphasis on their analytical and anti-counterfeiting applications and synthesis processes. Moreover, the fundamental principles behind the exceptional properties of fluorescent nanoparticles are discussed.

In this study, two types of thick steel plates are prepared by controlling carbon equivalent and nickel content, and their microstructures are analyzed. Tensile tests, Vickers hardness tests, and Charpy impact tests are conducted to investigate the correlation between microstructure and mechanical properties of the steels. The H steel, which has high carbon equivalent and nickel content, has lower volume fraction of granular bainite (GB) and smaller GB packet size than those of L steel, which has low carbon equivalent and nickel content. However, the volume fraction of secondary phases is higher in the H steel than in the L steel. As a result, the strength of the L steel is higher than that of the H steel, while the Charpy absorbed energy at -40 °C is higher than that of the L steel. The heat affected zone (HAZ) simulated H-H specimen has higher volume fraction of acicular ferrite (AF) and lower volume fraction of GB than the HAZ simulated L-H specimen. In addition, the grain size of AF and the packet sizes of GB and BF are smaller in the H-H specimen than in the L-H specimen. For this reason, the Charpy absorbed energy at -20 °C is higher for the H-H specimen than for the L-H specimen.

In this study, the correlation between microstructure and Charpy impact properties of FCAW(Flux cored arc welding) HAZ(Heat affected zone) of thick steel plates for offshore platforms was investigated. The 1/4 thickness(1/4t) location HAZ specimen had a higher volume fraction of bainite and finer grain size of acicular ferrite than those of the 1/2 thickness (1/2t) location HAZ specimen because of the post heat effect during the continuous FCAW process. The Charpy impact energy at -20 oC of the 1/4t location HAZ specimen was lower than that of the 1/2t location HAZ specimen because of the high volume fraction of coarse bainite. The Charpy impact energy at -40 and -60 oC of the 1/2t location HAZ specimen were higher than those of the 1/2t location HAZ specimen because the ductile fracture occurred in the fine acicular ferrite and martensite regions. In the ductile fracture mode, the deformed regions were observed in fine acicular ferrite and martensite regions. In the brittle fracture mode, long crack propagation path was observed in bainite regions.

Rare earth magnets are the strongest type of permanent magnets and are integral to the high tech industry, particularly in clean energies, such as electric vehicle motors and wind turbine generators. However, the cost of rare earth materials and the imbalance in supply and demand still remain big problems to solve for permanent magnet related industries. Thus, a magnet with abundant elements and moderate magnetic performance is required to replace rare-earth magnets. Recently, a”-Fe16N2 has attracted considerable attention as a promising candidate for next-generation non-rare-earth permanent magnets due to its gigantic magnetization (3.23 T). Also, metastable a”-Fe16N2 exhibits high tetragonality (c/a = 1.1) by interstitial introduction of N atoms, leading to a high magnetocrystalline anisotropy constant (K1 = 1.0MJ/m3). In addition, Fe has a large amount of reserves on the Earth compared to other magnetic materials, leading to low cost of raw materials and manufacturing for industrial production. In this paper, we review the synthetic methods of metastable a”-Fe16N2 with film, powder and bulk form and discuss the approaches to enhance magnetocrystalline anisotropy of a”-Fe16N2. Future research prospects are also offered with patent trends observed thus far.

Three kinds of STS304-Zr alloys were fabricated by varying the Zr content, and their microstructure and fracture properties were analyzed. Moreover, we performed heat treatment to improve their properties and studied their microstructure and fracture properties. The microstructure of the STS304-Zr alloys before and after the heat treatment process consisted of α-Fe and intermetallics: Zr(Cr, Ni, Fe)2 and Zr6Fe23. The volume fraction of the intermetallics increased with an increasing Zr content. The 11Zr specimen exhibited the lowest hardness and fine dimples and cleavage facets in a fractured surface. The 15Zr specimen had high hardness and fine cleavage facets. The 19Zr specimen had the highest hardness and large cleavage facets. After the heat treatment process, the intermetallics were spheroidized and their volume fraction increased. In addition, the specimens after the heat treatment process, the Laves phase (Zr(Cr, Ni, Fe) 2) decreased, the Zr6Fe23 phase increased and the Ni concentration in the intermetallics decreased. The hardness of all the specimens after the heat treatment process decreased because of the dislocations and residual stresses in α-Fe, and the fine lamellar shaped eutectic microstructures changed into large α-Fe and spheroidized intermetallics. The cleavage facet size increased because of the decomposition of the fine lamellarshaped eutectic microstructures and the increase in spheroidized intermetallics.

Recently, the grain boundary diffusion process (GBDP), involving heavy rare-earth elements such as Dy and Tb, has been widely used to enhance the coercivity of Nd-Fe-B permanent magnets. For example, a Dy compound is coated onto the surface of Nd-Fe-B sintered magnets, and then the magnets are heat treated. Subsequently, Dy diffuses into the grain boundaries of Nd-Fe-B magnets, forming Dy-Fe-B or Nd-Dy-Fe-B. The dip-coating process is also used widely instead of the GBDP. However, it is quite hard to control the thickness uniformity using dip coating. In this study, first, a DyF3 paste is fabricated using DyF3 powder. Subsequently, the fabricated DyF3 paste is homogeneously coated onto the surface of a Nd-Fe-B sintered magnet. The magnet is then subjected to GBDP to enhance its coercivity. The weight ratio of binder and DyF3 powder is controlled, and we find that the coercivity enhances with decreasing binder content. In addition, the maximum coercivity is obtained with the paste containing 70 wt% of DyF3 powder.

본 연구는 강원도 홍천군의 한우 거세우 3,926두의 도체등급판정 성적과 부분육 수율 조사자료를 이 용하여 도체등급판정과 관련된 형질들(도체중, 등지방두께, 등심단면적, 마블링 및 육량지수)과 부분육 생산관련 형질들(부분육 중량과 수율, 지방중량과 비율, 뼈 중량과 비율) 사이의 상관관계를 규명하기 위하여 실시하였다. 분석에 이용된 자료의 도축일령과 도체중의 평균치는 각각 952.53일과 454.58㎏이 었으며, 부분육 수율, 지방율 및 뼈율의 평균치는 각각 61.69%, 26.54% 및 11.77%였다. 도체중은 부분 육 중량, 지방중량, 뼈 중량 및 지방율과 정의 상관관계가 있었으며, 부분육 수율과는 부의 상관관계가 있었다. 등지방두께는 부분육 수율과는 부의 상관관계가 그리고 지방율과는 정의 상관관계가 있었으며, 등심단면적은 부분육 수율 및 지방율과 모두 정의 상관관계가 있었다. 마블링은 부분육 수율과의 상관 계수가 유의성이 인정되지 않는 작은 -0.01이었으며 지방율과의 상관계수가 유의성은 인정되었지만 작 은 크기의 양수인 +0.04였다. 육량지수는 부분육 수율 및 지방율과의 상관계수가 비교적 큰 크기의 +0.51 및 -0.57로 나타났다. 상관계수의 크기를 가지고 비교했을 때, 5개의 도체등급관련 형질 중 도 체중은 부분육 중량, 지방중량 및 뼈 중량에 가장 큰 영향을 미치며, 육량지수는 부분육 수율과 지방율 에 가장 큰 영향을 미치는 것으로 판단되었다. 도체중에 대한 부분육 중량과 지방중량의 단순 직선회귀 계수는 각각 +0.562 및 +0.364㎏, 그리고 육량지수에 대한 부분육 수율 및 지방율의 단순 직선회귀계 수는 각각 +0.341 및 -0.445%로 나타나서 도체중이 1㎏씩 증가할수록, 도체에서 회수되는 부분육 중 량이나 지방중량은 각각 0.562㎏ 및 0.364㎏ 증가할 것으로 예측되었으며, 육량지수가 1% 증가할수록 도체를 구성하는 부분육 비율은 0.341% 증가하고 지방의 비율은 0.445% 감소할 것으로 예측되었다.

We report a facile method for preparing KIT-1 mesoporous silicates with two different macroporous structures by dual templating. As a template for macropores, polystyrene (PS) beads are assembled into uniform three dimensional arrays by ice templating, i.e., by growing ice crystals during the freezing process of the particle suspension. Then, the polymeric templates are directly introduced into the precursor-gel solution with cationic surfactants for templating the mesopores, which is followed by hydrothermal crystallization and calcination. Later, by burning out the PS beads and the surfactants, KIT-1 mesoporous silicates with macropores are produced in a powder form. The macroporous structures of the silicates can be controlled by changing the amount of EDTANa4 salt under the same templating conditions using the PS beads and inverse-opal or hollow structures can be obtained. This strategy to prepare mesoporous powders with controllable macrostructures is potentially useful for various applications especially those dealing with bulky molecules such as, catalysis, separation, drug carriers and environmental adsorbents.

본 연구는 우리나라의 Holstein 능력검정 암소집단의 혈통자료를 이용하여 근교계수 및 혈통구조를 분석함으로써 Holstein 집단의 유전적 다양성 정도를 알아보고자 실시하였다. 2002년부터 2012년 사 이에 태어난 Holstein 400,029두에 대한 능력검정 자료 및 509,740두에 대한 혈통정보를 이용하여 분석하였다. 국내 지역별로 혈통완성도를 분석한 결과, 선조 3대까지의 조상을 알고 있는 개체의 비율 은 경기, 강원, 충남, 충북, 경북, 경남, 전남, 전북, 제주 및 우리나라 전체에 대해 각각 55.18, 23.49, 47.83, 53.62, 56.38, 51.35, 26.58, 49.41, 56.90 및 63.20%로 나타났다. 한편, 출생년도 별 평균근교계수는 2002년부터 2012년까지의 년도별 평균 및 전체에 대해 각각 0.43, 0.44, 0.58, 0.64, 0.78, 0.93, 1.08, 1.23, 1.46, 1.77, 2.03 및 0.93%로 추정되었다. 또한 아비에서 딸소까지 평균 세 대간격은 8.15년으로 나타났으며, 어미에서 딸소까지 평균 세대간격은 4.20년으로 나타났다. 근교계수 및 세대간격을 이용하여 추정한 국내 능력검정 젖소 집단의 유효집단크기는 2004, 2009 및 2012년에 대해 각각 56.5, 51.3 및 32.2두로 추정되어 시간이 지남에 따라 유효집단의 크기가 감소하는 것으로 추정되었다.

Zinc Sulfide (ZnS) is one of the II-VI semiconducting materials, having novel fundamental properties and diverse areas of application such as light-emitting diodes (LEDs), electroluminescence, flat panel displays, infrared windows, catalyst, chemical sensors, biosensors, lasers and biodevices, etc. However, despite the remarkable versatility and prospective potential of ZnS, research and development (R&D) into its applications has not been performed in much detail relative to research into other inorganic semiconductors. In this study, based on global patent information, we analyzed recent technical trends and the current status of R&D into ZnS applications. Furthermore, we provided new technical insight into ZnS applicable fields using in-depth analysis. Especially, this report suggests that ZnS, due to its infrared-transmitting optical property, is a promising material in astronomy and military fields for lenses of infrared systems. The patent information analysis in this report will be utilized in the process of identifying the current positioning of technology and the direction of future R&D.

As recognized by all scientific and industrial groups, carbon dioxide(CO2) capture and storage(CCS) could play an important role in reducing greenhouse gas emissions. Especially carbon capture technology by dry sorbent is considered as a most energy-efficient method among the existing CCS technologies. Patent analysis has been considered to be a necessary step for identifying technological trend and planning technology strategies. This paper is aimed at identifying evolving technology trend and key indicators of dry sorbent from the objective information of patents. And technology map of key patents is also presented. In this study the patents applied in korea, japan, china, canada, US, EU from 1993 to 2013 are analyzed. The result of patent analysis could be used for R&D and policy making of domestic CCS industry.

한국 재래돼지(KK) 69두 및 재래돼지 모돈과 듀록종 웅돈의 교배를 통하여 생산된 교잡종(KD) 88두 로부터 조사된 체중측정 기록에 대해 세 가지 비선형 성장곡선을 적용하여 KK(Korean Native Sow × Korean Native Boar) 및 KD(Korean Native Sow × Duroc Boar)의 성장모형을 추정하고, 추정된 성 장모형의 모수를 이용하여 KK와 KD에 대한 성장특성에 대한 기초자료를 제공하고자 실시하였다. 각각의 성장곡선 함수로 추정한 성장곡선은 다음과 같다. von Bertalanffy 모형의 경우 KK의 암컷, 수컷, KD의 암컷 및 수컷의 모형은 각각 , 및 로 추정되었다. Gompertz 모형의 경우 KK의 암컷, 수컷, KD의 암컷 및 수컷의 모형은 각각 ,, 로 추정되었다. Logistic 모형의 경우 KK의 암컷, 수컷, KD의 암컷 및 수컷의 모형은 각각 , , 및로 추정되었다. von Bertalanffy 모형의 경우 최대성장시기를 나타내는 변곡점()은 KK 암컷집단과 수컷집단에서 각각 4.40±0.12개월령 및 4.86±0.22개월령으로 추정되었고, KD 암컷 및 수컷집단에서는 각각 3.81±0.09개월령 및 4.00±0.08개월령으로 추정되었다. Gompertz 모형의 경우 는 KK암수 및 KD암수에 대해 각각 4.32±0.11개월령, 4.90±0.12개월령, 4.03±0.69개월령 및 4.11±0.06개월령으로 나타났다. Logistic 모형의 경우 는 KK암수 및 KD 암수에 대해 각각 4.18±0.07개월령, 4.41±0.05개 월령, 4.00±0.06개월령 및 4.03±0.04개월령으로 나타났다. 오차 평균 제곱합의 결과를 보면, KK의 성장은 Logistic, Gompertz 그리고 von Bertalanffy 모형 순으로 적합도가 좋은 것으로 판단되며, KD는 Gompertz, Logistic 그리고 von Bertalanffy 모형 순으로 적합도가 좋은 것으로 판단된다.