본 연구에서는 두 종류의 도너-억셉터 (D-A) 타입 고분자들을 Stille coupling 반응을 통하여 중합한 뒤, 이들 을 고분자 기반 유기 태양전지의 광활성 층으로 적용하였다. Benzodithiophene 전자 주게와 pyrazinoquinoxaline 전 자 받게를 활용하여 고분자들을 합성하였고, 전자 주게와 전자 받게가 직접 연결된 고분자를 PB-TMPQ 그리고 둘 사 이에 티오펜 π-bridge가 도입된 고분자를 PB-TTMPQ라 각각 명명하였다. 기본적인 화학 구조의 검증과 더불어, 고분 자들의 광학적 및 전기화학적 특성에 대한 분석 또한 실시하였다. 최종적으로 inverted-type 구조의 소자를 이용하여 고분자들의 광전지 특성들을 분석하였으며, PB-TMPQ와 PB-TTMPQ의 전력변환 효율은 각각 1.01%로 0.83%로 관측 되었다. 따라서, π-bridge의 도입이 pyrazinoquinoxaline 기반 고분자의 광전지 특성을 큰 영향을 미친다는 것이 확인 되었으며, 이러한 결과는 향후 pyrazinoquinoxaline 기반 고분자의 구조-물성 간 상관관계 연구에 활용될 수 있을 것 이다.

This study deals with the effects of austempering time on the microstructure and mechanical properties of ultrahigh strength nanostructured bainitic steels with high carbon and silicon contents. The steels are composed of bainite, martensite and retained austenite by austempering and quenching. As the duration of austempering increases, the thickness of bainitic ferrite increases, but the thickness of retained austenite decreases. Some retained austenites with lower stability are more easily transformed to martensite during tensile testing, which has a detrimental effect on the elongation due to the brittleness of transformed martensite. With increasing austempering time, the hardness decreased and then remained stable because the transformation to nanostructured bainite compensates for the decrease in the volume fraction of martensite. Charpy impact test results indicated that increasing austempering time improved the impact toughness because the formation of brittle martensite was prevented by the decreased fraction and increased stability of retained austenite.

To meet the current demand in the fields of permanent magnets for achieving a high energy density, it is imperative to prepare nano-to-microscale rare-earth-based magnets with well-defined microstructures, controlled homogeneity, and magnetic characteristics via a bottom-up approach. Here, on the basis of a microstructural study and qualitative magnetic measurements, optimized reduction conditions for the preparation of nanostructured Sm-Co magnets are proposed, and the elucidation of the reduction-diffusion behavior in the binary phase system is clearly manifested. In addition, we have investigated the microstructural, crystallographic, and magnetic properties of the Sm-Co magnets prepared under different reduction conditions, that is, H2 gas, calcium, and calcium hydride. This work provides a potential approach to prepare high-quality Sm-Co-based nanofibers, and moreover, it can be extended to the experimental design of other magnetic alloys.

This study investigates the effects of isothermal holding temperature and time on the microstructure, hardness and Charpy impact properties of medium-carbon bainitic steel specimens. Medium-carbon steel specimens with different bainitic microstructures are fabricated by varying the isothermal conditions and their microstructures are characterized using OM, SEM and EBSD analysis. Hardness and Charpy impact tests are also performed to examine the correlation of microstructure and mechanical properties. The microstructural analysis results reveal that granular bainite, bainitic ferrite, lath martensite and retained austenite form differently in the specimens. The volume fraction of granular bainite and bainitic ferrite increases as the isothermal holding temperature increases, which decreases the hardness of specimens isothermally heat-treated at 300 ℃ or higher. The specimens isothermally heat-treated at 250 ℃ exhibit the highest hardness due to the formation of lath martensite, irrespective of isothermal holding time. The Charpy impact test results indicate that increasing isothermal holding time improves the impact toughness because of the increase in volume fraction of granular bainite and bainitic ferrite, which have a relatively soft microstructure compared to lath martensite for specimens isothermally heat-treated at 250 ℃ and 300 ℃.

This paper presents a study of the microstructure and mechanical properties of commercial high-hardness armor (HHA) steels tempered at different temperatures. Although the as-received specimens of all the steels exhibit a tempered martensite structure with lath type morphology, the A steel, which has the smallest carbon content, had the lowest hardness due to reduced solid solution hardening and larger lath thickness, irrespective of tempering conditions. As the tempering temperature increases, the hardness of the steels steadily decreases because dislocation density decreases and the lath thickness of martensite increases due to recovery and over-aging effects. When the variations in hardness plotted as a function of tempering temperature are compared with the hardness of the as-received specimens, it seems that the B steel, which has the highest yield and tensile strengths, is fabricated by quenching, while the other steels are fabricated by quenching and tempering. On the other hand, the impact properties of the steels are affected by specimen orientation and test temperature as well as microstructure. Based on these results, the effect of tempering on the microstructure and mechanical properties of commercial high-hardness armor steels is discussed.

The resistance of metallic materials to ballistic penetration generally depends on a number of parameters related to projectile, impact, and armor plate. Recently, armor materials have been required to have various properties such as hardness, strength, and impact toughness in order to maintain an excellent ballistic resistance even after impact. In the present study, the influence of tempering on the microstructure and mechanical properties of an ARMOX 500T armor steel plate was investigated and then compared with those of S45C and SCM440 steels. As the tempering temperature increased, the hardness and strength gradually decreased, whereas the ductility and impact toughness clearly increased because the hardness, tensile, and impact properties were affected by the microstructural evolution and precipitation occurring during tempering. On the other hand, temper embrittlement appeared at tempering temperatures of 300 to 400 °C for the impact specimens tested at low temperature.

This present study deals with the effect of micro-alloying elements and transformation temperature on the correlation of microstructure and tensile properties of low-carbon steels with ferrite-pearlite microstructure. Six kinds of lowcarbon steel specimens were fabricated by adding micro-alloying elements of Nb, Ti and V, and by varying isothermal transformation temperature. Ferrite grain size of the specimens containing mirco-alloying elements was smaller than that of the Base specimens because of pinning effect by the precipitates of carbonitrides at austenite grain boundaries. The pearlite interlamellar spacing and cementite thickness decreased with decreasing transformation temperature, while the pearlite volume fraction was hardly affected by micro-alloying elements and transformation temperature. The room-temperature tensile test results showed that the yield strength increased mostly with decreasing ferrite grain size and elongation was slightly improved as the ferrite grain size and pearlite interlamellar spacing decreased. All the specimens exhibited a discontinuous yielding behavior and the yield point elongation of the Nb4 and TiNbV specimens containing micro-alloying elements was larger than that of the Base specimens, presumably due to repetitive pinning and release of dislocation by the fine precipitates of carbonitrides.

The purpose of this study is to examine the impact of perceived sustainability management fit of SPA brands on consumer purchase intention. A survey was conducted targeting women in their 20s and 30s from April 27th to May 6th 2013, and a total of 350 questionnaires were used in the final analysis. Frequency analysis, reliability analysis, factor analysis, ANOVA, simple regression analysis and multiple regression analysis were carried out using SPSS ver 21.0. The results of this study are as follows. First, fit of all three areas- economic, ecological and socialof sustainability management activities have a significant impact on consumer perception on sustainability activities. Second, perceived sustainability activities by SPA brands are found to have a positive effect on brand attitude, brand trust and consumer satisfaction. Third, brand attitude and consumer satisfaction forged by perceived sustainability activities by SPA brands have a positive impact on consumers' purchase intention. Based on the result of this study, the following marketing implications can be suggested. First, SPA brands need to be more active in all three area of sustainability activities while coming up with measures for differentiated social sustainability activities. Second, SPA brands need to meet their primary obligation by providing consumers with quality products at a reasonable price. Third, SPA brands need to recognize the potential value of sustainability activities as a driver of a longstanding relationship with consumers as well as long-term profit and value creation, leading to a great financial performance.

본 연구는 진사회성(eusocial)곤충으로 말벌과에 속하며 우리나라 고유종인 참 땅벌(Korean yellowjacket, Vespula koreensis)의 먹이자원의 이용도에 따른 포식 행동을 분석하였다. 둥지를 떠난 땅벌 일꾼은 제한된 정보를 바탕으로 스스로 의사 결정을 내려야 하고 집단에 속해있는 구성원으로서 집단의 필요를 충족시켜야 할 것이다. 이 연구는 참땅벌 일꾼들이 주어진 상황에서 어떻게 의사결정을 내리며 기 존의 분업을 이어가는지, 또는 기존의 확인되어진 포식재료 쪽으로 분업의 패턴을 바뀌어 나가는지를 분석하는 것이다. 포식 재료로 nectar(에너지원), pulp(둥지 재 료), prey(유충 먹이)를 공급하고, 에너지원인 nectar의 공급이 갑자기 끊어졌을 경 우 nectar forager의 분업 형태가 어떤 식으로 변화하는지를 보았다. 모든 포식재료 를 충분히 공급하였을 때의 각 forager 비율은 nectar forager가 15.0%, pulp forager 가 1.0%, prey forager가 84.0%로 나타났으며, nectar의 공급을 중단 후 전체 nectar forager의 8.3%는 pulp forager로, 66.7%는 prey forager로, 기타 25%로 분업 패턴 을 변화시킨 것으로 나타났다. 분업의 패턴을 바꾼 nectar forager들의 나이 개체변 인(크기, 몸무게 등)에 따른 분업의 패턴 변화를 추청해보고 비교 토의 하였다.

Mulberry Leaf (Morus-alba) is effective on reducing blood sugar increase and cholesterol in the blood. The objective of this study is to elucidate the sensory and physicochemical attributes of Mulberry Leaf Boogag with different amounts of glutinous rice paste and ginger juice. Mulberry Leaf Boogag, steamed for 90 seconds, was made by puffing the glutinous rice paste and ginger juice. The ratio of glutinous rice paste is made of a double, quintuple, and octuple proportion of water to the weight of the glutinous rice paste. The ratio of ginger juice is at a rate of one, three and five percent. According to the sensory evaluation, hardness and crispiness increased as the glutinous rice paste did, and ginger flavor, bitterness and sourness increased as the ginger juice did. Optimal conditions(p<0.05) were set when the value of hardness was more than five, and the value of bitterness and bitingness, lower than five. The optimal condition of Mulberry Leaf Boogag was established when the ratio of water to glutinous rice paste was 5.5, and in addition, 3.75 percent of ginger juice must be in proportion.

Rats are one of the most widely used animals in biomedical sciences because their metabolism and physiology are comparable to humans. In recent years, gene-targeted models have been developed using various animal species utilizing engineered nucleases such as clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated gene (Cas). It has recently become possible to efficiently transfect CRISPR/Cas into embryos via electroporation. However, electroporation can damage fertilized eggs; therefore, it is important to determine the optimal embryo culture conditions. A standardized approach for routine and reproducible rat transgenesis will render rat models more accessible for research. We performed experiments to obtain rat embryos with efficient superovulation and synchronization, and to investigate the appropriate medium conditions for pronuclear stage embryos subjected to electroporation stimulation for the introduction of engineered nuclease.