• Nuclear Engineering and Technology
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• 제42권6호
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• pp.670-679
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• 2010

In this paper, a new approach using a pixel-based correction method was developed to fix the non-uniform responses of flat-bed type scanners used for radiochromic film dosimetry. In order to validate the method's performance, two cases were tested: the first consisted of simple dose distributions delivered by a single port; the second was a complicated dose distribution composed of multiple beams. In the case of the simple individual dose condition, ten different doses, from 8.3 cGy to 307.1 cGy, were measured, horizontal profiles were analyzed using the pixel-based correcton method and compared with results measured by an ionization chamber and results corrected using the existing correction method. A complicated inverse pyramid dose distribution was made by piling up four different field shapes, which were measured with GAFCHROMIC$^{(R)}$EBT film and compared with the Monte Carlo calculation; as well as the dose distribution corrected using a conventional method. The results showed that a pixel-based correction method reduced dose difference from the reference measurement down to 1% in the flat dose distribution region or 2 mm in a steep dose gradient region compared to the reference data, which were ionization chamber measurement data for simple cases and the MC computed data for the complicated case, with an exception for very low doses of less than about 10 cGy in the simple case. Therefore, the pixel-based scanner correction method is expected to enhance the accuracy of GAFCHROMIC$^{(R)}$EBT film dosimetry, which is a widely used tool for two-dimensional dosimetry.

• Structural Engineering and Mechanics
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• 제77권2호
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• pp.197-215
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• 2021

Under a severe environment of multiple hazards such as earthquakes and winds, the life-cycle performance of engineering structures may inevitably be deteriorated due to the fatigue effect caused by long-term exposure to wind loads, which would further increase the structural vulnerability to earthquakes. This paper presents a framework for evaluating the lifetime structural seismic performance under the effect of wind-induced fatigue considering different sources of uncertainties. The seismic behavior of a high-rise steel-concrete composite frame with buckling-restrained braces (FBRB) during its service life is systematically investigated using the proposed approach. Recorded field data for the wind hazard of Fuzhou, Fujian Province of China from Jan. 1, 1980 to Mar. 31, 2019 is collected, based on which the distribution of wind velocity is constructed by the Gumbel model after comparisons. The OpenSees platform is employed to establish the numerical model of the FBRB and conduct subsequent numerical computations. Allowed for the uncertainties caused by the wind generation and structural modeling, the final annual fatigue damage takes the average of 50 groups of simulations. The lifetime structural performance assessments, including static pushover analyses, nonlinear dynamic time history analyses and fragility analyses, are conducted on the time-dependent finite element (FE) models which are modified in lines with the material deterioration models. The results indicate that the structural performance tends to degrade over time under the effect of fatigue, while the influencing degree of fatigue varies with the duration time of fatigue process and seismic intensity. The impact of wind-induced fatigue on structural responses and fragilities are explicitly quantified and discussed in details.

• 한국항공우주학회지
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• 제50권8호
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• pp.541-550
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• 2022

IMM 필터 및 GLRT 기법을 이용하여 무인기용 엔진의 효과적인 실시간 결함 진단 방안을 도출하였다. 이를 위해서 엔진 동적 사이클해석으로부터 선형 진단 모델을 유도하고 잔차 추정을 위한 칼만필터를 도입한 후 각 기법의 특성을 고찰하여 엔진 제어 구동기 및 센서의 결함 진단에 적용하였다. 이 과정에서 IMM 필터로부터 효과적인 FDI 방안을 도출하였고 구동기 결함으로 인한 상태변수의 반응값을 추정하였으며, GLRT로부터는 구동기 및 센서의 결함값 추정과 FDI 기능을 확인하였다. 수치 모의시험 결과를 통해서 FDI를 위한 IMM 필터의 효용성과 각 결함 모드의 결함값 추정을 위한 GLRT 기법의 효용성을 확인하였다.

• 한국전기전자재료학회논문지
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• 제35권6호
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• pp.523-546
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• 2022

Morphotropic phase boundary (MPB), which is a special boundary that separates two or multiple different phases in the phase diagram of some ferroelectric ceramics, is an important concept in identifying physics that includes piezoelectric responses. MPB, which had not been discovered in organic materials until recently, was discovered in poly(vinylidene fluoride-co-trifluoroethylene (P(VDF-TrFE)), resulting from a molecular approach. The piezoelectric coefficient of P(VDF-TrFE) in this MPB region was achieved up to -63.5 pC N^-1, which is about two times as large as the conventional value of -30 pC N^-1 of P(VDF-TrFE). An order-disorder arrangement greatly affects the rise of the piezoelectric effect and the ferroelectric, paraelectric and relaxor ferroelectric of P(VDF-TrFE), so the arrangement and shape of the polymer chain is important. In this review, we investigate the origin of negative longitudinal piezoelectric coefficients of piezoelectric polymers, which is definitely opposite to those of common piezoelectric ceramics. In addition to the mainly discussed issue about MPB behaviors of ferroelectric polymers, we also introduce the consideration about polymer chirality resulting in relaxor ferroelectric properties. When the physics of ferroelectric polymers is unveiled, we can improve the piezoelectric and pyroelectric properties of ferroelectric polymers and contribute to the development of next-generation sensor, energy, transducer and actuator applications.

• 동의신경정신과학회지
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• 제35권1호
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• pp.15-26
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• 2024

Objectives: The objective of this study is to develop a specialized clinical research protocol for acupuncture treatment specifically designed for disaster survivors based on insights from an expert survey. Methods: An expert panel comprising specialists in neuropsychiatry, acupuncture, and clinical research methodology was assembled. Initial data to inform the clinical research protocol design was collected utilizing open-ended responses, multiple-choice questions, and a 5-point Likert scale to gauge agreement levels. Next, this data was disseminated to a panel of experts. A cohesive clinical research protocol was then formulated during a core panel meeting by integrating insights from a panel of 10 experts. Results: The protocol developed herein entails a non-randomized controlled study involving participants aged 19~64 years old who have been identified as high-risk or cautious according to the National Trauma Center screening test. The study design includes the establishment of an active control group, which allows for the assessment of an additional effect through comparison with conventional therapy. The selected acupuncture approach involves a combination of manual acupuncture and ear acupuncture. For clinical outcome assessment, the Clinician-Administered Posttraumatic Stress Disorder Scale for DSM-5 was proposed to gauge trauma symptoms. Representative scales for various domains such as depression, anxiety, anger, insomnia, pain, and quality of life were also provided for reference. Conclusions: The developed protocol is anticipated to streamline the swift design and initiation of clinical trials during disaster scenarios. It is also designed to be scalable, thereby enabling its application in both non-randomized control group studies and single-group before-and-after comparisons.

• 유통과학연구
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• 제12권4호
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• pp.11-22
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• 2014

Purpose - The domestic franchise industry has made significant contributions to industry such as investment, employment, and community economy development, facilitating growth potential. The franchise industry provides management knowhow transfer between parent companies and franchisees as per contracts addressing use of business signs, franchisees' independent position, franchisor support, and royalties to be paid to the franchisors. However, many franchisors lack management knowhow and provide insufficient support because of poor control of franchisees and not having a systematic approach to support. This results in dissatisfied franchisees and failure to establish long-term relationships. Few studies have examined relational commitment and/or re-contract intention by support resources between franchisors and franchisees, despite a considerable output of theories and studies of the growth of the franchise industry. The purpose of this study, therefore, was to examine the effects of the ability to provide resources on relational commitments and re-contract intention, and to suggest causal relationships and implications. Research design, data, and methodology - The subject was domestic franchisors registered with the Association of Franchise with more than 50 franchisees. Franchisees under contract for 2 years and considering re-contract of their franchise 2 years later were used. The subjects totaled 300 franchisees in Seoul. A questionnaire survey was used to investigate the subject of franchisees' concessions during the 10 days from November 21, 2013 to November 30, 2013. After excluding 16 surveys with poor answers, 284 responses were finally used. Four areas and 44 questions were used. A nominal scale was used for four common characteristics questions including gender, ages, educational background, and franchise managing time. Questions regarding ability, relational commitment, and re-contract intention made use of a Likert 5-point scale. Data coding and data cleaning were used. SPSS 18.0 was used as follows. First, frequency analysis was done to investigate demographic characteristics. Second, exploratory factor analysis was done to verify validity of testing tools, and Cronbach's α coefficient was used to verify reliability. Third, correlation analysis and multiple regression analysis were done. An exploratory factor analysis was done to verify validity of concepts. A correlation analysis was done to test relationships between the variables, and multiple regression analysis was done to verify franchisor's ability, franchisees' relational commitment, and re-contract intention. Results - The following were the outcomes. First, store operation management, finance operation management, and human resource management affected the calculated bond. Second, store operation management and finance operation management affected the emotional bond. Third, store operation management, finance operation management, human resource management, and marketing management affected the prescriptive bond. Fourth, calculated bond and prescriptive bond had an effect on re-contract intention. Conclusions - As stated above, in franchise management, parent companies' offer and instruction of core competence to their franchisees as an information resource could improve the relational bond by helping them grow together through the resource sharing. Consequently, core competence factors were promoting factors that could improve franchisees' re-contract intention for a long time.

• BMB Reports
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• 제55권6호
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• pp.275-280
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• 2022

The treatment of atopic dermatitis (AD) is challenging due to its complex etiology. From epidermal disruption to chronic inflammation, various cells and inflammatory pathways contribute to the progression of AD. As with immunosuppressants, general inhibition of inflammatory pathways can be effective, but this approach is not suitable for long-term treatment due to its side effects. This study aimed to identify a plant extract (PE) with anti-inflammatory effects on multiple cell types involved in AD development and provide relevant mechanistic evidence. Degranulation was measured in RBL-2H3 cells to screen 30 PEs native to South Korea. To investigate the anti-inflammatory effects of Parasenecio auriculatus var. matsumurana Nakai extract (PAE) in AD, production of cytokines and nitric oxide, activation status of FcεRI and TLR4 signaling, cell-cell junction, and cell viability were evaluated using qRT-PCR, western blotting, confocal microscopy, Griess system, and an MTT assay in RBL-2H3, HEK293, RAW264.7, and HaCaT cells. For in vivo experiments, a DNCBinduced AD mouse model was constructed, and hematoxylin and eosin, periodic acid-Schiff, toluidine blue, and F4/80-staining were performed. The chemical constituents of PAE were analyzed by HPLC-MS. By measuring the anti-degranulation effects of 30 PEs in RBL-2H3 cells, we found that Paeonia lactiflora Pall., PA, and Rehmannia glutinosa (Gaertn.) Libosch. ex Steud. show an inhibitory activity of more than 50%. Of these, PAE most dramatically and consistently suppressed cytokine expression, including IL-4, IL-9, IL-13, and TNF-α. PAE potently inhibited FcεRI signaling, which mechanistically supports its basophil-stabilizing effects, and PAE downregulated cytokines and NO production in macrophages via perturbation of toll-like receptor signaling. Moreover, PAE suppressed cytokine production in keratinocytes and upregulated the expression of tight junction molecules ZO-1 and occludin. In a DNCB-induced AD mouse model, the topical application of PAE significantly improved atopic index scores, immune cell infiltration, cytokine expression, abnormal activation of signaling molecules in FcεRI and TLR signaling, and damaged skin structure compared with dexamethasone. The anti-inflammatory effect of PAE was mainly due to integerrimine. Our findings suggest that PAE could potently inhibit multi-inflammatory cells involved in AD development, synergistically block the propagation of inflammatory responses, and thus alleviate AD symptoms.

• 유통과학연구
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• 제13권3호
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• pp.61-67
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• 2015

Purpose - Exports have long been regarded as significant drivers of sustainable competitive advantage and growth among small and medium enterprises (SMEs). The export activities of SMEs are particularly important in the context of export-oriented economies such as Korea. Although many studies have examined the determinants of exports, it is difficult to find empirical studies about the determinants of the export performance of regional SMEs. This study investigates the determinants of export performance in the regional SME context based on an integrated approach that combines the environment factor of industrial organization theory, competitive strategy theory, and the competences of the resource-based view. Research design, data, and methodology - To empirically analyze the determinants of export performance in the regional SMEs, data were collected from firms in the Daegu metropolitan area. Data were collected directly through questionnaire surveys; in addition, secondary financial data were also taken from the KIS-VALUE database. Out of the 175 responses that were received, 143 were considered to be worth examining. After testing the reliability and validity of the variables through multiple items such as environmental turbulence and competitive strategy, hypotheses were verified by using five multi-regression models. These models were: a control model with organizational size and age, an environmental model with technology and market turbulence, a competency model with R&D and foreign distribution channels, a strategy model with product and market differentiation, and an integrated model including all of these variables. Results - First, as a control variable, the organization size has significant positive effects on export performance. Second, technology turbulence based on industrial organization theory has significant positive effects on export performance, but market turbulence does not affect export performance. Third, the foreign market distribution competency of the resource-based view has strong positive effects on export performance, but the R&D competency does not affect export performance. Fourth, the product differentiation strategy from competitive strategy theory positively impacts export performance, but market differentiation does not affect export performance. Finally, in the integrated model, only the foreign distribution competency of the resource-based view has a significant effect on export performance. Conclusions - The empirical results of this study verified the usefulness of the rationales behind the three theories to explain the export performance of the regional SMEs, especially the importance of the foreign market distribution competency from the resource-based view. With regard to practical considerations, this study's implications suggest that the use of technological environmental changes by industries is better than the use of market changes. Further, the use of the product differentiation strategy is more effective than the use of the market-driving strategy, and the distribution channel competency plays a stronger role than the technology-oriented competency with regard to the export performance position of regional SMEs. Future studies should examine relational perspectives, such as trust among channel partners. Therefore, the configuration approach is more useful in enhancing pragmatism by comparing high- and low-export companies.

• 한국과학교육학회지
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• 제34권8호
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• pp.703-718
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• 2014

이 연구에서는 지구, 지구 - 달 계, 태양계, 그리고 은하와 우주를 포함하는 천체의 구조와 운동을 종합한 천문 시스템(astronomical systems)의 학습 발달과정(learning progressions)을 조사하기 위하여, 순위 선다형 평가 문항을 개발하고 이를 초등/중학생들에게 적용한 검사 결과에 기반하여 학습 발달과정 해석의 타당성 검증의 근거를 제시하였다. 연구의 과정은 '구인특화, 평가문항 개발, 평가결과 기술, 측정 모델'로 이루어진 4 단계의 구인 모델링 방식(construct modeling approach)에 기반하여 진행되었다. 천문 시스템의 내용적 평가 구인으로 천체의 운동과 구조를 선정하였고, 탐구실행적 평가 구인으로 공간적 사고와 시스템 사고와 같은 천문학적 사고를 선정하였다. 이 연구에서 개발된 순위 선다형 평가 문항들은 천문 시스템에 대한 학습 발달과정을 조사하기 위한 검사 도구로서 적절하였다. 즉, item fit 분석 결과는 학생들의 문항 반응 결과가 Rasch 모델로 측정한 결과와 부합하였다. 그리고 Wright map 분석 결과는 이 연구의 평가 문항들이 천문시스템에 대한 학생들의 가설적 발달 경로를 조사하는데 매우 효과적임을 보여주었다. 학습 발달과정의 하위 정착점에서 학생들은 천체들의 위치와 운동 방향의 변화를 지구에서 보는 관점에서 2차원 평면으로 해석하는 공간적 사고 수준을 보였으며, 지구-달 계의 모델에서 천체의 위치와 변화를 부정확하게 연결하거나, 태양계 행성들과 은하수에 대한 단순한 패턴을 인식하는 시스템 사고 수준을 보였다. 학습발달과정의 중간 단계에서 학생들은 우주에서 내려다 본 지구 및 지구-달 계, 태양계의 모델을 근거로 천체의 운동을 해석하는 공간적 사고의 수준을 나타냈으며, 천체의 구조를 구성하는 요소들을 이 모델들과 연관시키는 시스템 사고를 보였다. 학습 발달과정의 상위 정착점에서 학생들은 우주에서 내려다 본 관점에서 형성된 천체의 운동 모델을 지구에서 바라 본 관점에서 얻은 자료와 서로 연관시키는 관점 전환의 공간적 사고를 지구의 운동, 지구-달 계의 운동, 태양계 행성의 운동, 은하와 우주의 운동에 적용할 수 있었다. 또한 상위 정착점에 도달한 학생들은 천문 시스템의 설명 모델을 구성하는 하위 요소들 간의 상호연관성을 파악하고 이를 설명 모델에 적용할 수 있는 시스템 사고를 나타냈다.

• 사회복지연구
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• 제37호
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• pp.63-89
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• 2008

본 연구는 성인 지적장애인의 비장애 형제들이 장애형제의 미래부양에 대해 갖는 책임감에 영향을 미치는 요인들을 규명하고자 하였다. 이를 위해 서울지역 8개 장애인종합복지관에서 서비스를 이용하는 만18세 이상의 성인 지적장애인을 형제로 두고 있는 비장애 형제들을 대상으로 설문조사를 실시하였다. 총132명의 자료가 최종 분석에 이용되었고, 다중회귀분석방법을 활용하여 지적장애인의 특성 요인 모형, 비장애형제의 특성 요인 모형, 관계적 요인 모형, 종합모형으로 분석하였다. 연구 결과, 지적장애인의 특성 요인에서는 장애정도가, 관계적 요인에서는 형제 간 친밀도와 사회적 지지가 유의미한 영향을 미치는 것으로 나타났다. 최종 종합모형에서는 장애 정도, 비장애형제의 성, 형제 간 친밀도와 사회적 지지가 유의미한 영향을 미치는 것으로 나타났으며, 이중 형제 간 친밀도와 사회적 지지를 포함한 관계적 요인이 부양 책임감을 예측하는 가장 중요한 요인인 것으로 밝혀졌다. 본 결과를 통해 지적장애인과 비장애 형제가 서로 간에 믿음과 이해를 증진시킬 수 있는 형제프로그램의 개발 및 확산이 요구되는 한편, 비장애형제가 가족이나 친구, 그 밖의 주변 사람들로부터 지지를 받을 수 있도록 대인관계망을 넓혀가도록 돕는 것이 중요하며, 또한 장애의 의존도에 따라 부양의 어려움을 경감시키기 위해 상이하게 접근할 필요가 있음을 시사하였다.