• Educational Technology International
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• 제17권1호
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• pp.117-150
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• 2016

The purpose of this study was to develop design guidelines on the learning analytics which can help to promote students' self-regulated learning (SRL) strategies in MOOCs learning environments. First of all, to develop the first draft of design guidelines, relevant literature review and case analysis on current MOOCs platforms such as edX, K-MOOC, Coursera, Khan Academy and FutureLearn were conducted. Then, to validate the design guidelines, expert reviews (validation questionnaires and in-depth interviews) and learner evaluation (in-depth interviews) were conducted. Through the recursive validation, the design guidelines were finalized. Overall, the final version of design guidelines on learning analytics to facilitate SRL strategies was suggested. The final design guidelines consist of 15 items in 10 categories related to the information analyzed based on individual student's learning behaviors and activities on MOOCs environments. Moreover, the results of interview also revealed that the social comparisons, learning progress reports, and personalization might contribute to the improvements of their SRL competences. This study has an implication that MOOCs could offer a higher success or completion rate to students with low SRL skills by taking advantage of the information on learning analytics

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권5호
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• pp.1238-1259
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• 2024

Previous studies on joint optimization of computation offloading and service caching policies in Mobile Edge Computing (MEC) have often neglected the impact of dependency-aware subtasks, edge server resource constraints, and multiple users on policy formulation. To remedy this deficiency, this paper proposes a many-objective joint optimization dependency-aware task offloading and service caching model (MaJDTOSC). MaJDTOSC considers the impact of dependencies between subtasks on the joint optimization problem of task offloading and service caching in multi-user, resource-constrained MEC scenarios, and takes the task completion time, energy consumption, subtask hit rate, load variability, and storage resource utilization as optimization objectives. Meanwhile, in order to better solve MaJDTOSC, a many-objective evolutionary algorithm TSMSNSGAIII based on a three-stage mating selection strategy is proposed. Simulation results show that TSMSNSGAIII exhibits an excellent and stable performance in solving MaJDTOSC with different number of users setting and can converge faster. Therefore, it is believed that TSMSNSGAIII can provide appropriate sub-task offloading and service caching strategies in multi-user and resource-constrained MEC scenarios, which can greatly improve the system offloading efficiency and enhance the user experience.

• 반도체디스플레이기술학회지
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• 제23권2호
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• pp.107-113
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• 2024

Scheduling of semiconductor test facilities has been crucial since effective scheduling contributes to the profits of semiconductor enterprises and enhances the quality of semiconductor products. This study aims to solve the scheduling problems for the wafer burn-in test facilities of the semiconductor back-end process by utilizing simulation and deep reinforcement learning-based methods. To solve the scheduling problem considered in this study. we propose novel state, action, and reward designs based on the Markov decision process. Furthermore, a neural network is trained by employing the recent RL-based method, named proximal policy optimization. Experimental results showed that the proposed method outperformed traditional heuristic-based scheduling techniques, achieving a higher due date compliance rate of jobs in terms of total job completion time.

• Journal of Photoscience
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• 제9권2호
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• pp.311-313
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• 2002

X-ray structures of pharaonis phoborhodopsin (ppR) show the different direction of the side chain of Arg72 from that of the corresponding residue (Arg82) of bacteriorhodopsin, BR. For BR, this residue is considered to play an important role in the proton pumping. In order to investigate the role of Arg72 in ppR, we constructed Arg72 mutants of R72A, R72K and R72Q, and measured the photocycle and proton pumping activities. The pH-titration curves on the absorption maximum of the mutants were shifted to alkaline in comparison of that of the wild-type. This may imply the increase of pKa of D75, suggesting the presence of the (probably electric) interaction between D75 and Arg72. Rate constants of the M-decay were 3-7 times faster than that of the wild-type, and the time for the completion of the photocycling was also reduced. Using Sn0$_2$ electrode, the rate of transmembrane proton transport was measured upon illumination. The photo-induced proton pumping activities were estimated after the corrections that are the percentages of the associated form of D75 (which has no pumping activity) and the photocycling rates. R72A and R72Q showed the reduced activity while R72K did not reduce the activity.

• 대한산업공학회지
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• 제38권2호
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• pp.80-88
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• 2012

This paper focuses on small touch key size and spacing that affect the usability of the smart phones. The experiments examined thirty-six different touch key designs, combinations of four touch key sizes (width (mm) ${\times}$height (mm); $4{\times}4$, $4{\times}7$, $7{\times}4$, and $7{\times}7$), and nine spacings (horizontal (mm)${\times}$vertical (mm); $0{\times}0$, $0{\times}1$, $0{\times}3$, $1{\times}0$, $1{\times}1$, $1{\times}3$, $3{\times}0$, $3{\times}1$, and $3{\times}3$). Forty participants volunteered in the experiment. The completion time, error rate, identification discomfort, and control discomfort were measured. The results revealed that the touch key sizes of $7{\times}7$ and $7{\times}4$ provide the best performance in terms of the error rate measure, while the touch key size of $7{\times}7$ provides the best results for other measures. In addition, touch key spacings of $1{\times}1$, $1{\times}3$ and $3{\times}1$ are regarded as the best for all the measures. The results of this study suggest a practical approach for the small touch key design for the smart phones.

• Radiation Oncology Journal
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• 제31권2호
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• pp.66-71
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• 2013

Purpose: We evaluated the effectiveness and safety of ipsilateral radiotherapy for the patient with well lateralized tonsil cancer: not cross midline and <1 cm of tumor invasion into the soft palate or base of tongue. Materials and Methods: From 2003 to 2011, twenty patients with well lateralized tonsil cancer underwent ipsilateral radiotherapy. Nineteen patients had T1-T2 tumors, and one patient had T3 tumor; twelve patients had N0-N2a disease and eight patients had N2b disease. Primary surgery followed by radiotherapy was performed in fourteen patients: four of these patients received chemotherapy. Four patients underwent induction chemotherapy followed by concurrent chemoradiotherapy (CCRT). The remaining two patients received induction chemotherapy followed by radiotherapy and definitive CCRT, respectively. No patient underwent radiotherapy alone. We analyzed the pattern of failure and complications. Results: The median follow-up time was 64 months (range, 11 to 106 months) for surviving patients. One patient had local failure at tumor bed. There was no regional failure in contralateral neck, even in N2b disease. At five-year, local progression-free survival, distant metastasis-free survival, and progression-free survival rates were 95%, 100%, and 95%, respectively. One patient with treatment failure died, and the five-year overall survival rate was 95%. Radiation Therapy Oncology Group grade 2 xerostomia was found in one patient at least 6 months after the completion of radiotherapy. Conclusion: Ipsilateral radiotherapy is a reasonable treatment option for well lateralized tonsil cancer. Low rate of chronic xerostomia can be expected by sparing contralateral major salivary glands.

• 대한기계학회논문집B
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• 제40권8호
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• pp.485-494
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• 2016

본 연구는 TMED 방식 병렬형 하이브리드 차량을 이용하여 회생제동 회수율 및 연비 특성 실험에 대한 것이다. 회생제동 기술은 하이브리드 차량의 에너지 효율 향상을 위해 필수적인 기술로 판단되어 연구를 수행하였다. 따라서 병렬형 하이브리드 차량과 Eddy Current 방식의 차대동력계를 통해 IM240 모드 실험 시 초기 SOC 상태, 주행 모드 특성, 운전자의 운전특성에 따른 연비 특성을 회생 제동 측면에서 전류 특성 및 전류수지에 대한 비교 분석을 수행하였다. 본 연구결과, 초기 SOC 상태가 낮을수록 하이브리드 차량의 엔진 작동 시간이 증가 하고 에너지 효율이 낮아지는 것을 알 수 있었다. 또한 주행 모드 특성, 운전자의 운전 특성에 따른 연비 특성 실험 결과 평균 연비 차이는 크게 나지 않았지만, 최종 SOC 상태에 따라서 모드 종료 후 엔진 작동 유무의 차이가 있음을 알 수 있었다.

• Journal of Chest Surgery
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• 제47권5호
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• pp.451-457
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• 2014

Background: The balance of the risks and the benefits of cardiac surgery in the elderly remains a major concern. We evaluated the early and mid-term clinical results of patients aged over 75 years who underwent major cardiovascular surgery. Methods: Two hundred and fifty-one consecutive patients, who underwent cardiac surgery at Seoul National University Bundang Hospital between July 2003 and June 2011, were included in this study (mean age, $78.7{\pm}3.4$ years; male:female=130:121). Elective surgery was performed in 112 patients, urgent in 90, and emergency in 49. Results: Early mortality was 12.7% (32/251). Follow-up completion was 100%, and the mean follow-up duration was $2.8{\pm}2.2$ years. Late mortality was 24.2% (53/219). There were 283 readmissions in a total of 109 patients after discharge. However, the reason for readmission was related more to non-cardiac factors (71.3%) than to cardiac factors. The overall survival estimates were 79.2% at the 1-year follow-up and 58.4% at the 5-year follow-up. Patients who underwent elective surgery had a lower early mortality rate (elective, 4.5%; urgent, 13.3%; emergency, 30.6%) and better overall survival rate than those that underwent urgent or emergency surgery (p<0.001). Conclusion: The timing of cardiac surgery was found to be an independent risk factor for early and late mortality. Thus, earlier referral and intervention may improve operative results. Further, comprehensive coordinated postoperative care is needed for other comorbid problems in aged patients.

• 멤브레인
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• 제13권4호
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• pp.268-282
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• 2003

불완전 분리의 실질적인 분리투과 특성을 근거로 하는 모사모델을 이용하여 투과증발 막촉진 에스터화 반응의 실질적인 거동을 연구하였다. 막의 분리효율, 막의 물제거 능력을 모델에 포함시킴으로써 반응모사를 통하여 이들이 막촉진반응에 어떻게 영향을 끼치는지를 체계적으로 관찰할 수 있었다. 막을 통한 비완전분리가 일어날 경우에 초기 반응물 몰비율이 1이 아닐 때 반응 혼합물중 소량으로 존재하는 반응성분이 투과되거나, 혹은 초기 반응물 몰비율이 1인 반응 혼합물중 어느 반응성분이 투과되든지 반응이 완결될 수 없었다. 생성물인 에스터가 물과 함께 일부 투과될 경우 정방향 반응속도를 증가시켜 시간에 따른 반응 전환률을 증가시킨다. 막을 통한 불완전 분리시 막을 통한 투과로 인하여 발생하는 반응혼합물의 부피감소로 인하여 반응성분 뿐 아니라 생성성분의 농도가 증가되는데 이들 농도증가가 반응속도에 상반된 영향을 끼친다; 반응물 농축은 반응속도를 증가시키나 생성물 농축은 역방향의 반응을 촉진시킴으로서 반응속도를 감소시킨다. 반응초기에는 반응물 농축효과가 우세하나 반응이 진행됨에 따라 생성물 농축효과가 우세하여 반응속도를 저하시킴이 모사결과 관찰되었다.

• Journal of Korean Biological Nursing Science
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• 제17권3호
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• pp.228-235
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• 2015

Purpose: Although the prevalence rate of chronic diseases is rapidly increasing due to an unhealthy diet in Korea, nurses may not have enough nutritional knowledge to educate their patients. This study investigated the level of nurses' nutritional knowledge for chronic diseases as well as for strokes, and the needs for nurses' nutritional education. Methods: This research is a descriptive research conducted from April to August of 2014, on 242 nurses who work with stroke patients, in two tertiary general hospitals in the city of Seoul, South Korea. Results: The average nutritional knowledge score of our subjects was $19.9{\pm}2.51$ (range 12-24). The correct response rate was 83% which was higher than expected. However, many nurses (31-66%) answered incorrectly on items such as 'Drinking low-fat milk is better than whole milk', and 'Seasoning with a large amount of soy sauce instead of salt can reduce sodium consumption'. We also found that nurses who received continuing education regarding nutrition scored higher than those who did not (p=.020). There was no correlation between nutritional knowledge and the need for nutritional education (r=.034, p=.601). Conclusion: The level of nutritional knowledge of the nurses was relatively low and irrelevant to the completion of nutrition courses during university or duration of experience. Rather, the relevance was higher when the nurse received nutrition-related training after graduating from university. Our results imply that continuous nutritional education is necessary for hospital nurses.