• Bulletin of the Korean Chemical Society
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• 제22권11호
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• pp.1255-1260
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• 2001

The expansion of two different kinds of hydrodynamic size of polymethyl methacrylate (PMMA Mw: 1.56- 2.04 ${\times}$ 106 g/mol) has been measured by dynamic light scattering and viscometry above the Flory $\theta$ temperature of the variou s solvents such as n-butyl chloride, 3-heptanone, and 4-heptanone. The expansion of PMMA chains was analyzed in terms of universal temperature parameters and also compared with previous results of polystyrene (PS) system. First it was found that simple $\tau/{\tau}c$ parameter no longer had its universality for the expansion behavior of hydrodynamic size in the chemically different linear polymer chains. However after modifying ${\tau}/{\tau}c$ parameter into $(Mw/Ro2)3}2(\tau/\tauc)$, we observed a much better universality for both PMMA and PS systems. Here Mw, Ro, $\tau[=(T-{\theta}$)/${\theta}$]$, and ${\tau}c[=({\theta}-Tc)/Tc]$ are defined as the weight average molecular weight, the unperturbed end-to-end distance, the reduced temperature and the reduced critical temperature, respectively.

• Computers and Concrete
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• 제20권6호
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• pp.689-704
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• 2017

The paper presents experimental and numerical investigations of prefabricated composite structural building reinforced concrete slabs with the insulating material for a residential building construction. The building slabs were composed of concrete and expanded polystyrene. In experiments, the slabs in the full-scale 1:1 were subjected to vertical concentrated loads and failed along a diagonal shear crack. The experiments were numerically evaluated using the finite element method based on two different constitutive continuum models for concrete. First, an elasto-plastic model with the Drucker-Prager criterion defined in compression and with the Rankine criterion defined in tension was used. Second, a coupled elasto-plastic-damage formulation based on the strain equivalence hypothesis was used. In order to describe strain localization in concrete, both models were enhanced in the softening regime by a characteristic length of micro-structure by means of a non-local theory. Attention was paid to the formation of critical diagonal shear crack which was a failure precursor.

• Archives of Plastic Surgery
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• 제48권4호
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• pp.384-388
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• 2021

Adequate positioning of the hand is a critical step in hand fracture operative repair that can impact both the clinical outcome and the efficiency of the operation. In this paper, we introduce the use of a thermoplastic splint with an added thumb stabilizing component as a means to increase the surgeon's autonomy and to streamline the patient care pathway. The thermoplastic splint is custom fabricated preoperatively by the specialist hand therapist. The splint is used prior, during, and post operation with minimal modification. The thumb component assists maintaining the forearm in a stable pronated position whilst drilling and affixing metal work. This is demonstrated in the video of removal of metal work and open reduction and internal fixation of a metacarpal fracture.

• Communications for Statistical Applications and Methods
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• 제28권4호
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• pp.351-368
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• 2021

For a probabilistic model with positively skewed data, a lognormal distribution is one of the key distributions that play a critical role. Several lognormal models can be found in various areas, such as medical science, engineering, and finance. In this paper, we propose a new estimator for a lognormal mean and depict the performance of the proposed estimator in terms of the relative mean squared error (RMSE) compared with Shen's estimator (Shen et al., 2006), which is considered the best estimator among the existing methods. The proposed estimator includes a tuning parameter. By finding the optimal value of the tuning parameter, we can improve the average performance of the proposed estimator over the typical range of σ². The bias reduction of the proposed estimator tends to exceed the increased variance, and it results in a smaller RMSE than Shen's estimator. A numerical study reveals that the proposed estimator has performance comparable with Shen's estimator when σ² is small and exhibits a meaningful decrease in the RMSE under moderate and large σ² values.

• Tuberculosis and Respiratory Diseases
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• 제82권3호
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• pp.179-189
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• 2019

Although recent advances in molecular targeted therapy and immuno-oncology have revolutionized the landscape of lung cancer therapeutics, cytotoxic chemotherapy remains an essential component of lung cancer treatment. Extensive evidence has demonstrated the clinical benefit of chemotherapy, either alone or in combination with other treatment modalities, on survival and quality of life of patients with early and advanced lung cancer. Combinational approaches with other classes of anti-neoplastic agents and new drug-delivery systems have revealed promising data and are areas of active investigation. Chemotherapy is recommended as a standard of care in patients that have progressed after tyrosine kinase inhibitors or immune checkpoint inhibitors. Chemotherapy remains the fundamental means of lung cancer management and keeps expanding its clinical implication. This review will discuss the current position and future role of chemotherapy, and specific consideration for its clinical application in the era of precision medicine.

• Structural Engineering and Mechanics
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• 제78권1호
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• pp.103-116
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• 2021

In this work, a model of a functionally graded (FG) nanotube conveying fluid embedded in an elastic medium is developed based on the nonlocal strain gradient theory (NSGT) in conjunction with Euler-Bernoulli beam theory (EBT). The main objective of this research is to investigate the nonlinear vibration and stability analysis of fluid-conveying nanotubes. The governing equations of motion are derived by means of Hamiltonian principle. The analytical expressions of nonlinear frequencies and critical flow velocities for two different types of boundary conditions including pinned-pinned (P-P) and clamped-clamped (C-C) conditions are obtained by employing Galerkin method as well as Hamiltonian Approach (HA). Comparison of the obtained results with the published works show the acceptable accuracy of the current solutions. The effects of the power-law index, the nonlocal and material length scale parameters and the elastic medium on the stability and nonlinear responses of FG nanotubes are thoroughly investigated and discussed.

• 한국응용곤충학회지
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• 제31권3호
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• pp.304-313
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• 1992

The agricultural industry is beset by continuing demands to decrease the use of pest control agents which employ toxic modes of action. Although there are real problems of pesticide resistance, and sometimes overuse or redistribution in the environment, much criticism results from a lack of appreciation of how small is the risk involved. Whatever the background reasons, research and development for pesticide alternatives, particularly within Integrated Pest Management systems, is clearly of high priority. Currently available approaches, including use of natural products and molecular biology, are often regarded with naive optimism and require critical appraisal. For the future, methods of pest control based on chemicals with non-toxic modes of action (e.g. pheromones) continue to offer promise but, for widespread use, will require their integration with biological agents and development by means of plant molecular biology.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.341-346
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• 2005

After the IMF shock, some major construction companies in Korea have been motivated to avoid and mitigate various risk factors which could be critical and catastrophic events to corporate revenue and organization internally or externally. It means that they are trying to introduce and set up a risk management plan and system suitable to their organization and culture. L construction co. ltd. is one of major construction companies that have been searching methodologies or technologies to manage various risk factors surrounding corporate marketing and project operation. This paper presents an unique approach to develop a model of risk management plan and system suitable to L construction itself focused on the construction phase.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.463-467
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• 2015

Mega-shock means a sporadic event such as the earning shock, which occurred by sudden market changes, and it can cause serious problems of profit loss of international construction projects. Therefore, the early response and prevention by analyzing and predicting the Mega-shock is critical for successful project delivery. This research is preliminary study to develop a prediction model that supports market condition analysis and Mega-shock forecasting. To avoid disadvantages of classic statistical approaches that assume the market factors are linear and independent and thus have limitations to explain complex interrelationship among a range of international market factors, the research team explored the Fractal Theory that can explain self-similarity and recursiveness of construction market changes. The research first found out correlation of the major market factors by statistically analyzing time-series data. The research then conducted a base of the Fractal analysis to distinguish features of fractal from data. The outcome will have potential to contribute to building up a foundation of the early shock warning system for the strategic international project management.

• 한국산학기술학회논문지
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• 제10권6호
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• pp.1376-1379
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• 2009

근래 특급호텔을 중심으로 호텔정보시스템(Hotel Information System, HIS)의 도입과 활용이 활성화되고 있다. 이러한 HIS의 도입은 호텔경영에서 혁신적인 변화를 일으키고 있다. 이러한 상황에서 HIS의 성공요소에 대한 관심과 그에 대한 연구가 많은 관심을 받고 있다. 그러나 대부분의 HIS에 대한 연구는 HIS 시스템의 도입 시점을 전제로 한 성공요인에 대한 연구에 집중되어 있다. 이는 HIS 시스템의 운용보다 도입에 관점을 둔 것으로, 시간 변화에 따른 요인의 중요도의 변화에 대한 설명이 부족하다. 이러한 관점에서 살펴보면, 호텔정보 시스템에 대한 포괄적인 성공요인을 도출한 후에 그 성공요인들의 시간에 따른 중요도 변화를 측정하기 위해서 호텔경영의 성공을 위한 HIS의 성공 요인의 성숙 시점을 예측하는 것은 매우 중요하다 하겠다. 따라서 본 연구에서는 E. M. Rogers[2]의 혁신이론을 기초하여 시간(Time)의 변화에 따른 HIS의 주요성공요인 (Critical Success Factors, CSFs)의 성숙 시점을 예측하였다. 본 연구를 위한 설문 조사는 2009년 1월 25일부터 3월 10일까지 전국 주요 호텔을 대상으로 각 호텔의 관리자 2명씩 선정하여 실시하였다. 회수 설문 중 유효 설문 84부의 응답을 연구에 활용하였으며 데이터 분석은 통계분석 패키지인 SPSS R10.1.3을 활용하였다. 설문 구성의 신뢰성을 측정하는 Cronbach ${\alpha}$ 값은 0.7239로 나타나 유의한 것으로 판단하였다.