In this study, we investigate the deformation behavior of Hf44.5Cu27Ni13.5Nb5Al10 metallic glass powder under repeated compressive strain during mechanical milling. High-density (11.0 g/cc) Hf-based metallic glass powders are prepared using a gas atomization process. The relationship between the mechanical alloying time and microstructural change under phase transformation is evaluated for crystallization of the amorphous phase. Planetary mechanical milling is performed for 0, 40, or 90 h at 100 rpm. The amorphous structure of the Hf-based metallic glass powders during mechanical milling is analyzed using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Microstructural analysis of the Hf-based metallic glass powder deformed using mechanical milling reveals a layered structure with vein patterns at the fracture surface, which is observed in the fracture of bulk metallic glasses. We also study the crystallization behavior and the phase and microstructure transformations under isothermal heat treatment of the Hf-based metallic glass.

Electrical wire explosion in liquid media is a promising method for producing metallic nanopowders. It is possible to obtain high-purity metallic nanoparticles and uniform-sized nanopowder with excellent dispersion stability using this electrical wire explosion method. In this study, Ni-Fe alloy nanopowders with core-shell structures are fabricated via the electrical explosion of Ni-Fe alloy wires 0.1 mm in diameter and 20 mm in length in de-ionized water. The size and shape of the powders are investigated by field-emission scanning electron microscopy, transmission electron microscopy, and laser particle size analysis. Phase analysis and grain size determination are conducted by X-ray diffraction. The result indicate that a core-shell structured Ni-Fe nanopowder is synthesized with an average particle size of approximately 28 nm, and nanosized Ni core particles are encapsulated by an Fe nanolayer.

목 적: 젊은 성인에게 조절부담 완화방법으로 낮은 가입도의 모노비전, 변형된 모노비전 및 멀티포컬 소 프트 콘택트렌즈를 처방한 후 시기능에 미치는 영향을 평가하였다. 방 법: 20대 성인 22명(23.36±2.57 세)을 대상으로 단초점 콘택트렌즈, 모노비전, 변형된 모노비전, 멀 티포컬 콘택트렌즈를 단순맹검법으로 양안에 착용시키고 일주일의 적응기간이 경과한 후 조절을 유도하기 위하여 콘택트렌즈를 착용한 상태에서 1시간 동안 40 cm 거리에서 동영상을 시청하도록 한 후 양안 개방상 태에서 양안 원·근거리 대비시력, 입체시력, 가독력, 유령상(ghost image), 바늘귀에 실꿰기 및 시기능 관 련 설문지를 이용하여 평가하였다. 결 과: 양안 원거리 100% 대비시력과 양안 근거리 100%와 10% 대비시력은 교정방법에 따라 차이가 없 었고 단초점 콘택트렌즈와 차이가 없었으나, 10% 원거리 대비시력은 모노비전에서 가장 낮았다(p<0.05). 입 체시력은 모노비전의 경우 가장 낮았으며(p<0.05), 다른 교정방법은 단초점 콘택트렌즈와 차이가 없었다. 가독력은 모노비전 콘택트렌즈를 착용했을 때 가장 느리고 부정확했으며(p<0.05), 다른 교정방법은 단초점 콘택트렌즈와 차이가 없었다. 유령상(ghost image)은 교정방법 사이에 차이가 없었다. 원·근거리 시력, 입 체시, 적응도에 대한 설문 만족도 조사에서는 변형된 모노비전과 멀티포컬 콘택트렌즈는 단초점 콘택트렌즈 와 차이가 없었지만 모노비전은 다른 방법보다 만족도가 낮게 나타났다. 결 론: 젊은 성인에서 낮은 가입도의 변형된 모노비전 콘택트렌즈와 멀티포컬 콘택트렌즈 착용 후 시기능 은 단초점 콘택트렌즈와 유의한 차이가 없었지만 모노비전의 경우에는 저대비 원거리시력, 입체시력, 가독력 및 시기능 만족도가 저하되는 것으로 나타났다.

Repetitive applications of drugs to tumor tissues and animals induced resistance and/or tolerances which caused severe problem in agriculture and medicine. However, we still do not clearly understand the molecular and cellular mechanisms underlying development of resistance and tolerance to chemicals. Drosophila is one of the most widely used model for studying fundamental phenomena in sciences using its available genetic and genomic resources. To investigate unknown molecular and cellular basis of drug resistance development, we applied Drosophila with two different concentrations of a chemical after treating them with Ethyl methanesulfonate mutatgenesis. We found that flies treating with two different concentration of chemicals showed different susceptibility to a chemical. We have established two different lines showing different susceptibility to a chemical. We will use these lines to compare any differences in mRNA expression profiling and enzyme activities. (This work was supported by project title: Investigation on cross drug resistance mechanisms using Drosophila as a model (PJ010821032016) from Rural Development Administration).

The purpose of current study was to examine bioaccessibility of antioxidant activity and total phenolic content in each part of water spinach (Ipomoea aquatic Forsk.). In vitro biomimicking system simulated human digestive fluid was employed in order to measure bioavailable anti-oxidative effect and phenolic content. Antioxidant activity and total phenolic content was measured by using the DPPH method and the Folin-Ciocalteu assay, respectively. Stem of water spinach had a higher DPPH free radical scavenging effect (5.43 mg/mL for IC50) than leaf (5.95 mg/mL for IC50), while leaf had a greater level of total phenolic content (287.45 μg GAE/mL) than stem (216.45 μg GAE/mL). Bioaccessible antioxidant capacity and digestive stability of total phenolic content showed a similar pattern to what found in raw materials. Our result also indicated that total phenolic content was not found to be a major marker for prediction of antioxidant activity. It is plausible that other constituents such as vitamin E and C in water spinach could be contributors for antioxidant activities.

The purpose of this study is to investigate the effect of quality of management discussion and analysis (MD&A) disclosure on stock price crash risk. The MD&A can be seen to reflect the management's intention on public announcement and reveals directly what the management says to communicate with outside investors. A firm's high-quality MD&A implies the management's commitment to communicating with the market, not allowing the managers to have incentives to hoard unfavorable news, which if revealed to the public, may lead to downward stock price corrections, damaging corporate values. The high-quality MD&A is, thus, likely to reduce the stock price crash risk. We use a logistic regression to test whether MD&A influences crash risk using listed companies in the Korean Stock Exchange (KSE) stock market between 2010 and 2013. Findings of the empirical test show that the higher the quality of MD&A, the less likely crash risk appears, implying that the MD&A disclosed adequately can be one of the factors mitigating firm's stock price crash risk. This study has implications as it presents the MD&A disclosure as a factor influencing stock price crash risk and suggests voluntary disclosure as well as mandatory disclosure acts as a variable that explains the risk of stock price crash.

This study was conducted to investigate needs and operational status for care farming of education or experience farms in South Korea. A questionnaire made up of 38 questions was developed for this study. The survey was conducted online among owners in education and experience farms (total 264 sites) in Seoul and nine provinces in September 2017. A total of 78 questionnaires were collected and the response rate was 44.6%. As the results, the purposes of farm operation reported as experience (85.9%), education (79.5%), production of agricultural products (67.9%), and healing (47.4%). Main visitors in education and experience farm were children and adolescents (89.7%), adults (51.3%), and families (46.2%). A farm activity program was mainly provided by a one-time experience using crops (69.2%), animals (16.7%), and food processing activity (10.3%). Fifty percent of the responding farmers received support from the government and the local government such as public relations (32.5%), operational funding (32.5%), and management consulting (15.0%). The lack factor of operating in farms was lower profit system (24.4%), poor farm infrastructure (21.8%), and lack of promotion and marketing ways (16.7%). 97.5% of the respondents reported ‘very necessary’ and ‘necessary’ of care farming. Specifically, the care farming service reported that priority should be given to children and adolescents (55.1%) and people with emotional and behavior disorder (15.4%). The present study is anticipated to offer the efficient management of care farm and provides reference data of the policy suggestion for care farming setting in South Korea.

Rapeseed cake was extracted with 80% ethanol and then fractionated with H2O (fraction I) as well as with 30% (II), 50% (III), 70% (IV), and 100% ethanol (V). Total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, ferric-reducing antioxidant potential, and Trolox equivalent antioxidant capacity were in the order of fractions II > III > I > IV > V. The three fractions with high antioxidant activities and TPC (I, II, and III) were pooled and hydrolyzed by NaOH solution, resulting in 18.97 mg sinapic acid/g hydrolyzed extract and 21- and 2.2-fold increases in TPC and DPPH radical scavenging activity, respectively. Hydrolyzed rapeseed cake extracts (200, 500, and 1,000 ppm) and catechin (200 ppm) as a comparison were added to 10% fish oil-in-water emulsion, and their effects on oxidative stability were investigated by measuring hydroperoxide values (PV) during refrigerated storage. PVs were significantly lower in the emulsions with added hydrolyzed extract as compared to the control (p<0.05) and significantly decreased with increasing extract concentration (p<0.05) over a period of 29 days. The emulsion added with hydrolyzed extract showed higher PV than that added catechin at the same concentration (200 ppm) during 13-22 days (p<0.05), but after then, the PV was not significantly different (p>0.05). This study indicates that hydrolyzed rapeseed cake extract rich in sinapic acid may inhibit oxidation in a fish oil-in-water emulsion in a concentration-dependent manner.

본 연구는 총 여덟 가지 실외원예활동 동작의 운동학 및 운동역학적 특성을 분석하기 위해 수행되었다; 땅고르기, 땅파기, 종자파종, 모종 심기, 근거리 잡초뽑기, 원거리 잡초뽑기, 저위치 수확하기, 고위치 수확하기. 20대 남자 대학생 총 24명(평균 연령 : 23.4 ± 2.93세)이 본 연 구에 참여하였다. 삼차원 동작분석 시스템(Qualisys Track Manager 2.7 build 783)과 지면반력기기(Kistler Instruments)를 이용하여 무게 중심, 관절각도와 같은 운동학적 요인과 지면반력, 압력중심, 관절모멘트와 같은 운동역학적 요인을 측정하였다. 또한 표면 근전도기기 (Desktop DTS)를 이용하여 총 16개 양측 몸통과 하지근육의 근육활성도를 측정하였다. 그 결과 총 여덟 가지의 실외원예활동 동작은 1) 한 발 내딛기(예 : 땅고르기, 땅파기), 2) 쭈그려 앉기(예 : 종자파종, 모종심기, 근거리 잡초뽑기, 원거리 잡초뽑기), 3) 허리 구부리기(예 : 저위 치 수확하기, 고위치 수확하기)로 구분되었다. 각 동작은 다시 세 개 또는 네 개의 구간으로 세분화되었다. 원예활동 동작 수행 시 무게중심 은 전·후 방향과 상·하 방향으로 이동하였다. 전·후 방향으로 무게중심 이동이 가장 많은 원예활동은 땅고르기였고, 상·하 방향으로 가장 많은 무게중심 이동이 나타나는 원예활동은 종자파종이었다(p = 0.001). 무게중심 이동으로 불안정해진 신체균형을 유지하기 위한 보상적 움직임으로 지면반력 발생, 압력중심 이동, 하지 관절과 근육의 결합운동이 발생했다. 총 여덟 가지 실외원예활동은 원예활동 수행방법에 따라 운동학 및 운동역학적 특성의 차이를 보였다(p = 0.05). 따라서 본 연구의 결과는 노인과 재활환자의 균형감 향상을 위한 원예치료 프 로그램 개발 시 유용한 기초자료로서 활용되어 질 것이다.