• 한국토양환경학회지
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• 제1권2호
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• pp.73-81
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• 1996

실험실 내에서 부피비로 약 50%내외의 수분함량을 가진 3개의 서로 다른 깊이의 토양에서 염소와 중수의 확산계수는 4.8$\times$ $10${-7}$ 부터 7.2$\times$ $10${-7}$ $\textrm{cm}^2$/sec와 5.5 $\times$ $10${-5}$ 부터 1.6$\times$ $10${-4}$ $\textrm{cm}^2$//sec였다. 한편, 물과 물질의 이동성에 대한 연구는 중간사로 구성된 토양층 위에 위치하는 점토로부터 미사질 양토에 속하는 약 70cm깊이의 토양에서 실시되었고, 87일간의 실험기간동안 리터당 15.2$m\ell$의 염소와 0.6bq의 중수로 처리된 물을 일정한 유량(2cm/일)으로 관개하였다. 토양의 깊이와 시간에 따른 염소와 중수의 변동위치는 suction probe에 채취된 토양수를 가지고 측정하였는데 실험지 안에서 서로 다른 깊이 또는 동일 위치에서 염소와 중수가 발견되었다. 이러한 실험의 결과로부터 추정컨대 토양수의 유속과 표면확산 계수가 염소와 중수의 분포에 직접적인 영향을 미쳤고 24개의 suction probe에서의 결과는 실질적 물질과 토양의 상호작용의 효과를 나타내는 순수치의 25% 내외에서 평가치를 추정할 수 있었다.

• Journal of Korean Dental Science
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• 제10권1호
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• pp.10-21
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• 2017

Purpose: The purpose of this study was to investigate the electrochemical characteristics of nanotubular Ti-25Nb-xZr ternary alloys for dental implant materials. Materials and Methods: Ti-25Nb-xZr alloys with different Zr contents (0, 3, 7, and 15 wt.%) were manufactured using commercially pure titanium (CP-Ti), niobium (Nb), and zirconium (Zr) (99.95 wt.% purity). The alloys were prepared by arc melting in argon (Ar) atmosphere. The Ti-25Nb-xZr alloys were homogenized in Ar atmosphere at $1,000^{\circ}C$ for 12 hours followed by quenching into ice water. The microstructure of the Ti-25Nb-xZr alloys was examined by a field emission scanning electron microscope. The phases in the alloys were identified by an X-ray diffractometer. The chemical composition of the nanotube-formed surfaces was determined by energy-dispersive X-ray spectroscopy. Self-organized $TiO_2$ was prepared by electrochemical oxidation of the samples in a $1.0M\;H_3PO_4+0.8wt.%$ NaF electrolyte. The anodization potential was 30 V and time was 1 hour by DC supplier. Surface wettability was evaluated for both the metallographically polished and nanotube-formed surfaces using a contact-angle goniometer. The corrosion properties of the specimens were investigated using a 0.9 wt.% aqueous solution of NaCl at $36^{\circ}C{\pm}5^{\circ}C$ using a potentiodynamic polarization test. Result: Needle-like structure of Ti-25Nb-xZr alloys was transform to equiaxed structure as Zr content increased. Nanotube formed on Ti-25Nb-xZr alloys show two sizes of nanotube structure. The diameters of the large tubes decreased and small tubes increased as Zr content increased. The lower contact angles for nanotube formed Ti-25NbxZr alloys surfaces showed compare to non-nanotube formed surface. The corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface showed longer the passive regions compared to non-treatment surface. Conclusion: It is confirmed that corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface has longer passive region compared to without treatment surface.

• 한국지구과학회지
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• 제32권3호
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• pp.334-345
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• 2011

이 연구의 목적은 학교 현장에서 문제중심학습을 적용할 수 있는 초등 교사들의 교수 실행의 능력과 교육 환경을 알아보기 위한 것이다. 참가자들은 초등학교 수준에서 문제중심학습을 강의하는 강사로 활동중이었다. 초등학교 교사 3인이 연구에 참여하였으며, 자료는 반구조화된 면담을 통해 획득되었다. 문제중심학습과 관련된 교사들의 면담은 두 가지 주요 주제로 나누어 분석되었다. (1) 문제중심학습에서 요구되는 교사들의 교수 실행의 능력 (2) 문제중심학습을 적용할 수 있는 교육 환경. 연구 결과는 다음과 같다. 첫째, 문제중심학습은 전통적인 교수학습 방법보다 수업 준비와 교수 과정에 어려움이 있었다. 그러나 문제중심학습에서 교사들은 자율적이고 허용적인 학습 분위기 속에서 학생들이 자기 주도적인 학습을 할 수 있도록 안내하는 도우미로서 행동한다는 점에서, 학생들은 잠재능력을 효과적으로 계발할 수 있는 동기를 부여받는다. 이를 위하여 교사는 문제중심학습 전체에서 효과적인 학습 활동이 이루어질 수 있도록 끊임없는 노력과 시간을 투자해야 한다. 둘째, 문제중심학습을 적용할 수 있는 교육적 환경을 위하여, 교사들은 동료교사, 학생, 학부모, 교육 행정가들의 문제중심학습에 대한 인식의 확산과 교사들의 커뮤니티 형성해야 한다. 문제중심 학습의 확산을 위해 가장 중요한 것은 교사들이 직접적으로 교수 활동에 문제중심학습을 적용해 보는 것이다. 문제중심 학습을 하면 학생들의 변화가 나타날 것이고, 이러한 효과를 경험한 교사는 교수학습과정에 문제중심학습을 채택하게 될 것이다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권1호
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• pp.275-282
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• 2015

Background: Breast cancer (BC) is the most-common malignancy of women worldwide. Though there are differences among developed and developing countries, BC remains the most common cancer type of women in Turkey. Objective: This study aimed to identify the level of knowledge, awareness, and their potential predictors towards BC in Ankara, Turkey. Materials and Methods: The present descriptive study was conducted on 376 females attending a breast health outpatient clinic. A self-administered questionnaire was designed to evaluate knowledge level about BC and predictors effecting its level. Data analysis was performed using the chi-square test. A value of p<0.05 was considered statistically significant. Results: Mean age of the participants was $46.2{\pm}9.93$ (22-75). The majority (92.6 %) were married; 41.5% were educated less than nine years. Most of the women were housewives (82.7%) and, were living in an urban region (86.4%). Predictors of effecting responses to seven knowledge and awareness questions about BC varied from demographic features including older age groups, higher educational levels, being married, living in an urban area, being employee, smoking, having greater BMI to additional attributes associated breast health such as the increased number of births, applying for the purpose of control, positive family history of breast diseases, any diagnoses of breast diseases and performing BSE practice. Conclusions: It was determined that females in Turkey have better knowledge of BC than other developing countries even though it is not at the desired level. These findings revealed that females should be more informed about BC risk factors, prognosis and treatments by primary health-care providers to counteract the ascending burden of this disease.

• Asian Pacific Journal of Cancer Prevention
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• 제16권10호
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• pp.4339-4345
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• 2015

Occupational exposure to wood dust is one cause of nasopharyngeal cancer (NPC); however, assessing this exposure remains problematic. Therefore, the objective of this study was to develop a semi-quantitative exposure assessment method and then utilize it to evaluate the association between occupational exposure to wood dust and the development of NPC. In addition, variations in risk by histology were examined. A case-control study was conducted with 327 newly diagnosed cases of NPC at the National Cancer Institute and regional cancer centers in Thailand with 1:1 controls matched for age, gender and geographical residence. Occupational information was obtained through personal interviews. The potential probability, frequency and intensity of exposure to wood dust were assessed on a job-by-job basis by experienced experts. Analysis was performed by conditional logistic regression and presented in odds ratio (ORs) estimates and 95% confidence intervals (CI). Overall, a non significant relationship between occupational wood dust exposure and NPC risk for all subjects was observed (ORs=1.61, 95%CI 0.99-2.59); however, the risk became significant when analyses focused on types 2 and 3 of NPC (ORs=1.62, 95%CI 1.03-2.74). The significant association was stronger for those exposed to wood dust for > 10 year (ORs=2.26, 95%CI 1.10-4.63), for those with first-time exposure at age > 25 year (ORs=2.07, 95%CI 1.08-3.94), and for those who had a high cumulative exposure (ORs=2.17, 95%CI 1.03-4.58) when compared with those considered unexposed. In conclusion, wood dust is likely to be associated with an increased risk of type 2 or 3 NPC in the Thai population. The results of this study show that semi-quantitative exposure assessment is suitable for occupational exposure assessment in a case control study and complements the information from self-reporting.

• 유통과학연구
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• 제13권3호
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• pp.51-60
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• 2015

Purpose - Among potential marketing strategies, the most efficient method to encourage purchase intention is through sales promotions. Sales promotions also serve to enhance customer satisfaction, which is closely related to the incidence of repurchases. Therefore, the success of retail stores greatly depends on the effectiveness of their promotional activities. The present study aimed to obtain the necessary information for apparel stores to establish more effective promotional activities. To this end, the study's specific research questions were to examine 1) consumer satisfaction with the recent sales promotions of retail apparel stores, 2) the levels of consumer preferences for different types of sales promotions (cash discounts, promotional gifts, prize drawings, discount coupons, stamp cards, or mileage cards), and 3) the differences in purchase intention according to preference levels for different types of sales promotions. Research design, data, and methodology - The research employed a descriptive survey method using a self-administered questionnaire. The sample consisted of 700 men (n=234) and women (n=466) ranging in age from their 20s to their 50s and residing in the Seoul area. Data were analyzed through methods including factor analysis as well as Cronbach's α coefficients, the t-test, ANOVA, and the Duncan test. Results - Differences among consumer preferences were identified for each type of sales promotion according to the purchase amount and the customer's age. In relation to purchase amounts below 500,000 won, participants in their 50s have lower preferences for price discounts than those in their 20s or 30s, whereas participants in their 40s or 50s have lower preferences for stamp cards and mileage cards than those in their 20s. When the purchase amount is greater than 500,000 won, housewives have higher preferences for promotional gifts than respondents with other occupations. However, no gender differences were found with regard to preference levels for the different types of sales promotions. Respondents generally exhibited mediocre satisfaction with the sales promotion events of retail apparel stores. They also expressed negative opinions about sales promotions when such promotions lead to high prices, as well as dissatisfaction with the poor quality of promotional gifts. It was also found that, regardless of the purchase amount, the groups with higher preferences for discount coupons and mileage cards displayed higher purchase intentions. Only when the purchase amount is greater than 200,000 won did the group with higher preferences for lottery system promotional gifts express higher purchase intentions. On the other hand, for all purchase amount sizes, there were no differences in purchase intentions according to preferences for cash discounts, promotional gifts, or stamp cards. Conclusions - The results revealed that greater effort must be devoted to enhancing consumers' satisfaction levels with the promotional activities performed by apparel retail stores. The results also showed that it is necessary to differentiate among sales promotion strategies according to preference levels for different types of sales promotions, purchase amounts, and target consumer ages.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제21권2호
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• pp.154-159
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• 2015

과거 어플리케이션 다양성만 지향하던 사용자의 수요가 최근 스마트폰의 고도화된 센서와 기계학습이 결합된 지능형 어플리케이션으로의 선호로 전향되고 있다. 이러한 경향을 반영하여 본 논문에서는 스마트폰에 축적된 사용자의 라이프로깅 데이터에서 의미있는 정보를 추출하고, 추출한 정보를 통해 사용자의 인지적 행동을 대신 가능한 인지 에이전트(Cognitive Agent)개념의 스마트폰-사용자 상호작용 사용자 맞춤 위치-시간-행동 추론 기법을 제안한다. 제안 방법은 사용자의 라이프로깅데이터를 DPGMM (Dirichlet Process Gaussian Mixture Model) 클러스터링 기법으로 사용자 주요 관심지역 POI(Point of Interest)를 자동으로 추출하고, 평생학습이 가능한 강화학습의 한 종류인 POMDP(Partially Observable Markov Decision Process)를 사용하여 사용자의 위치-시간-행동을 추론 한다. 제안 방법으로 구현한 사용자 맞춤 일과 계획 시스템의 시간별 사용자 일과 추론 결과는 70%이상의 성능을 보였으며, 하루 일과 계획 지능형 서비스의 새로운 방향을 제시하고 있다.

• 대한지역사회영양학회지
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• 제23권1호
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• pp.60-72
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• 2018

Objectives: This study was conducted to investigate the awareness of energy drinks, energy drink consumption behaviors, and associated factors among college students. Methods: A total of 536 students from three universities in Cheongju completed a self-administered questionnaire regarding awareness and consumption of energy drinks as well as general characteristics, health-related characteristics, and eating habits. Results: Approximately half of the respondents reported they knew what energy drinks were, while 45.7% had heard of energy drinks but did not know what they were. However, 76.9% had experience in using energy drinks. The main reason for using energy drinks was to stay awake, and the main place that they were used was on campus or at the library. More than 70% of energy drink users did not read the caffeine contents of energy drinks. After consuming energy drinks, 31.3% experienced adverse effects, the most serious being sleep disturbance. Approximately 33% of students consumed energy drinks once a month or more frequently, and men consumed energy drinks more frequently than females. Energy drink users who consumed at least one drink each month were more likely to be natural science major or drink more milk for male students, and to have more allowances or consume less meat for female students, compared with non-users. Conclusions: Our study showed that 33% of students consumed at least one energy drink each month, and there were a small number of students consumed energy drinks almost every day or energy drinks mixed with alcohol. Accordingly, college students should be taught potential health hazards of energy drinks mixed with alcohol as well as energy drinks alone. In addition, reading labels about caffeine and sugar contents in energy drinks is encouraged.

• 생명과학회지
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• 제29권12호
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• pp.1329-1336
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• 2019

뇌에서 뇌실하 영역은 자가 복제 및 신경세포와 교세포로 분화하는 신경줄기세포가 위치한 곳이다. 이러한 신경줄기세포는 태어난 직후 뿐만 아니라, 성인기까지 존재한다. 세포 증식과 분화에 대한 결정은 세포 안과 밖의 상황에 따라 조절될 필요가 있기에, 많은 세포 내부 또는 세포 외부의 인자들이 이러한 결정에 관여한다. 이러한 인자들 중에서 미토콘드리아는 신경줄기세포의 운명 결정에 관여함이 보고된 바 있다. 본 저자들의 이전 논문에서, 미토콘드리아 저해제인 rotenone을 장시간 처리했을 때, 신경세포로의 분화가 거의 일어나지 않았음을 보여주었다. 이번 연구에서, rotenone을 뇌실하 영역 신경줄기세포에 단기간 처리했을 때의 영향에 대해 조사하였다. 이를 통해 다음과 같은 결과를 관찰하였다. (1) 하루 동안 rotenone을 처리하자 신경세포로의 분화가 크게 감소하였고, 특히 분화 초기 단계가 더 민감하게 억제되었다. (2) 일시적 증식세포인 Mash1+ 세포의 수가 rotenone을 하루 처리한 후 감소하였다. (3) 분화가 된 Tuj1+ 신경세포와 Olig2+ 희소 돌기 아교 세포 (oligodendrocytes) 모두 rotenone을 단기간 처리하자 감소하였다. 반면, glial fibrillary acidic protein (GFAP)+성상 세포 (astrocytes)의 수는 변화하지 않았다. (4) sulfiredoxin 1 (Srxn1) 유전자 발현이 rotenone을 하루 처리한 후 증가하였는데, 이는 nuclear factor (erythroid-derived 2)-like 2 (Nrf2) 신호전달 경로가 활성화 되었음을 말해준다. 이러한 실험 결과는 기능을 갖춘 미토콘드리아가 신경세포 또는 희소 돌기 아교 세포로의 분화 뿐 아니라, 이미 분화가 끝난 신경세포의 유지에도 필요함을 확인해 주었다. 또한, 이러한 결과는 rotenone과 같은 미토콘드리아의 저해제에 짧은 시간 노출 되더라도 신경줄기세포의 신경세포로의 분화 가능성에 장기적인 영향을 미칠 수 있음을 시사한다.

• 한국식생활문화학회지
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• 제29권6호
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• pp.648-658
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• 2014

The aim of this study was to investigate the relationships between eating habits and health among adolescents in Shanghai and Heze, China. A cross-sectional study was conducted in 2013 on 2,089 adolescents; 1,089 students were from Shanghai and 999 students from Heze region. Eating habits, weight, height, and nutritional knowledge were assessed using a self-administered questionnaire. Eating habits score was classified into two categories: healthy eating habits and unhealthy eating habits, based on "Korean Youth Risk Behavior Web-based Survey", for statistical data analysis. Associations between eating habits, BMI, and nutritional knowledge were examined using a general linear model with adjustment of potential confounding factors such as region, gender, age, parents' education level, and pocket money. Statistical analyses were performed using the SAS (version 9.3) program. Proportions of healthy eating habits group were 90.0% for breakfast (3-7 times/wk), 29.1% for fruit (${\geq}once/d$), 12.5% for vegetable (${\geq}3times/d$), 7.3% for milk (${\geq}2times/d$), 90.0% for fast food (<3 times/wk) consumption, respectively. The average BMI score was 20.1 (Shanghai 20.5 Heze 19.6), which is in the range of normal weight. Rates of obesity and overweight were 16.5% and 8.3% in Shanghai and Heze, respectively. There were significant negative correlations between intake frequencies of breakfast, fast food, biscuits, sugar, chocolate, and BMI score. Eating habits and nutritional knowledge score showed a significant positive correlation. These results showed better eating habits regarding eating regularity and consumption of fruits and soft drinks in Chinese adolescents compared with Korean adolescents, although cultural differences were not fully considered. This study demonstrated significant associations of BMI and nutritional knowledge with dietary behavior in Chinese adolescents in two regions of China. Further studies on Chinese adolescents from other regions in China should be considered.