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A Review of the Possible Causes of Negative Source Impedance in Fluid Machines (유체기계에 있어서 부의 음원 임피던스의 원인에 관한 고찰)

  • ;Keith S. Peat
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.3
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    • pp.76-82
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    • 2001
  • Most fluid machines can be considered as periodic noise sources when operated under constant conditions, which allows for a frequency domain representation of the source and the associated acoustic field In the duct. In such a representation, the source is characterized by frequency-dependent values of both strength and impedance. Although knowledge of these values can be gained by either experimentation or by modeling, one-port acoustic characteristics of an in-duct source with high flow velocity, high temperature, and high sound level can be measured only by the multiload method using an overdetermined set of open pipes with different lengths as applied loads. However, the problem is that negative source resistances have been often measured. This paper reviews the possible causes of the problem, with reference to experimental and theoretical results, in an attempt to clarify the issue. A new interpretation is given for the violation of basic assumptions and the defect in the algorithm of multiload method. The major cause and mechanism of the problem is due to the violation of time invariance assumption of the source and the load impedance can seriously affect the final measured result of source impedance.

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O.P.E.N Triad: The Future Success for Individuals, Institutes, and Industries

  • Kim, Hae-Jung;Forney, Judith;Crowley, Ruth
    • Journal of the Korean Society of Clothing and Textiles
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    • v.34 no.12
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    • pp.1980-1991
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    • 2010
  • This study proposes the O P E N Triad framework as a future set of tools and perspectives for individual members and institutes to further their professional and academic potential as well as prospect and vitalize the future of the Korean Clothing and Textiles discipline through a global perspective. The millennial generation desires On-demand, Personal, Engaging, and Networked (O P E N) experiences effecting cultural change for creative and influential interaction in transactions, communication, and education. O P E N Individuals offers a WebSphere model as a holistic learning system that has a synergizing value of education across academic courses, industries, and cultures. Through a digitalized and virtualized class, it complements relevant technologies already familiar to the student population. By employing environmental scanning approaches, the most influential and viable future global issues related to the clothing and textiles discipline are identified and dialogued within O P E N Institutes. For future clothing and textiles institutes, this scanning allows them to be open to new ideas, to focus on inter-engagements, to collaborate among individuals, to associate as a part of web of people, organizations, and ideas, to personalize an institutes curricula, and to dialogue generative knowledge. O P E N Industries reveals three dominant future issues that cross academia and industry, sustainability, supply chain management, and social networking. In-depth interviews with U.S. industry experts identified interdependent gaps in global consumer experience practices and suggested the following gaps as future research areas: a standardized business model to the entrepreneurial model, strategic management to a sustainable competitive advantage, standardized to differentiated products, services and operations, market segmentation to global consumer clusters, business-driven marketplaces to consumer-engaged marketspaces, and excellent services to optimal experience. This O P E N Triad framework empowers millennial students, universities, and industries to anticipate and prepare for a radically changing world.

Effects of Materials of Drainage Layer at the Reclaimed Soil Base on Tree Growth at the Open Space of Saemangeum Sea Dike (새만금 방조제 개활지의 준설토 기반에 대한 배수층재 처리가 수목 생육에 미치는 효과)

  • Lee, Hanna;Lim, Joo-Hoon;Koo, Namin;Bae, Sang-Won
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.18 no.1
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    • pp.13-23
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    • 2015
  • This study was performed to compare the effects of different drainage layers on tree growth at the exposed sites of Saemangeum sea dike. 4 types of drainage layers including control(dredged soil), specially prepared bark, gravel, and wood chip were set in 150~165cm depth of soil. Pinus thunbergii and Celtis sinensis were planted after 9 months of soil treatment. Electrical conductivity(EC) of soil in all treated plots were decreased under $4dS{\cdot}m^{-1}$, and NaCl(%) was decreased under 0.05% after 1 year from soil treatment. Soil moisture at the 120cm depth of the bark treated plot was higher than that of the 180cm soil depth, below the drainage layer. It is considered that vertical mobility of water was inhibited. Organic matter(OM) at the 120cm soil depth increased at bark and wood chip treated plots. Survival rates after 4 years of P. thunbergii and C. sinensis were 100% in all treatments. The height of P. thunbergii was not significantly different among the treatments while the height of C. sinensis was significantly different among the treatments and it was highest at the bark treated plot.

Fresh Produce Container Operated with a Routine of Hypobaric Application, CO2 Injection and Diffusion Tube Opening for Keeping Beneficial Modified Atmosphere

  • Park, Su Yeon;An, Duck Soon;Lee, Dong Sun
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.26 no.2
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    • pp.53-60
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    • 2020
  • A concept of household container to create and keep the modified atmosphere (MA) beneficial for fresh produce mix was devised and tested under typical chilled storage conditions of 3℃. The container system containing mixed products is initialized by applying weak hypobaric condition (0.9 atm) and subsequently injecting CO2 gas at an appropriate low level (0.03 atm). The passive atmosphere modification by produce respiration is then induced to reach a target until gas diffusion tube of proper dimension starts to open. The design was made to attain quasi-steady state mass balance of O2, CO2 and N2 to maintain the desired MA through the storage. Interrupted opening for taking out or placing some products was to reinitialize the loop of control logic. The developed concept was tested by the container which held commodities of spinach, pak choi, oyster mushroom, peeled onion, strawberry and cut carrot. The target optimum MA of 11% O2 and 10% CO2 (0.11 and 0.10 atm, respectively) was set to avoid injurious range of O2 and CO2 concentrations for any commodities. The developed container system could work to reach and maintain beneficial MA of 0.10-0.12 atm O2 and 0.07-0.10 atm CO2 close to the target during the storage contributing to quality retention of products measured in weight loss, chlorophyll content of spinach, ascorbic acid content of pak choi, color of onion, texture of oyster mushroom, bacterial count of strawberry and carotenoids of carrot. The container system shows potential to improve current preservation practice of fresh produce mix on consumers' level.

Grounded Theory Approach on the Adaptation Process in Facility of Long-Term Care Elderly (장기요양보호대상노인의 시설적응과정에 관한 근거이론적 접근 -내버려진 마음 누그러뜨리기-)

  • Shin, Yongseok;Kim, Soojung;Kim, Jungwoo
    • Korean Journal of Social Welfare
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    • v.65 no.3
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    • pp.155-182
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    • 2013
  • The purpose of this study is to examine how the long-term care effects the elderly that adapt themselves to the caring facility, what their experiences are and what kinds of behavioral characteristics they present. We have analyzed the research conducted on 15 elderly individuals who are living in an elderly long-term care facility, by using the grounded theory approach of Strauss and Corbin (1998). As a result, 170 concepts, 42 sub-categories, and 15 categories were set by the open coding process. During the adaptation process in a long-term care facility, the primary experience or feeling by the elderly is that they had been 'deserted'. However, when consolidating the casual conditions, contextual conditions, intervening conditions, the action/interaction strategy, and consequence, the primary experience was that the elderly came to an 'acceptance'. Such acceptance was then sub-categorized into a destiny-resignation type, reality-acceptance type, and voluntary-selection type. Based on the results of this study, we recommend practical alternatives which will improve surrounding circumstances including caring facilities, its employees, relationships with other elderly individuals, and family support.

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A Study on Mate Selection and Sex Consciousness reflected in Samguk Yusa (三國遺事에 나타난 配偶者 選擇 및 性意識에 관한 연구)

  • Baik, Kyung-Im;Kim, Il-Myung
    • Journal of the Korean Home Economics Association
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    • v.37 no.1
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    • pp.1-13
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    • 1999
  • The purpose of this study is to find how the mate selection and sex consciousness reflected in Samhuk Yusa. We set up the following two questions for aim of this study. First, how are the real aspects and specific characters of mate selection reflected in Samguk Yusa? Second, how are the real aspects and specific characters of sex consciousness reflected in Samguk Yusa? The results can be summarized as follows; 1. Mate selection reflected in Samguk Yusa discussed into two major domains, one is spouse conditions and the other is marriage form. Men and Women are married at teenages, but the greater part of case is unidentified, so in order to approach this we need to analyse other historical documents. In men and women, standard of appearance and personality is difference. Analyzed case about appearance is a few, also we need to analyse other historical materials. More valued personality is wisdom in men, and in women more valued personality is virtue, brightness, graceful and mild. Through in case of to overcome the cultural gabs, the society must be open in every area. The marriage form is diversity, examples, free marriage, a marriage of convenience type, etc. Especially in aspects remarriage of man and woman is free in every class. 2. Sex consciousness reflected in Samguk Yusa discussed into three major domains, first is discussion about sex, second is premarital sexual behavior, third is extramarital. Through the case of discussion about sex is opened so there is not existence double blinded in sexual norms. Also through the case of premarital sexual behavior and extramarital, fidelity ideology does not yet come into existence.

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A Study on the Development of Design Prototype for Physical Education(PE) Uniforms of Elementary School (초등학생 학교체육복 디자인 프로토타입 개발에 관한 연구)

  • Moon, Myengok;Kim, Eunjung;Lee, Jinsuk
    • Fashion & Textile Research Journal
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    • v.18 no.5
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    • pp.677-684
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    • 2016
  • This study was done for the proposal for improvement for junior sportswear which is substitutable as uniforms in the form of elementary school and physical education uniforms by analyzing detailed features through investigation. Accordingly, we developed a prototype design for physical education uniforms as a symbol of the school to enhance the aesthetic and functional satisfaction. The results are as follows. When we developed physical education uniforms, we put activity on our first priority while taking the improvement in both aesthetic and functional aspects into consideration. In addition, we tried to make sure the uniforms reflect the refined and trendy elements to meet students needs to satisfy their aesthetic sense in dress. Reflecting the improvement proposals and preferences of the students, six different prototype designs were developed and evaluated on the basis of two concepts of "new basic" and "trendy". The highest ranking, the physical education uniforms design 1 is based on new basic concept and characterized with slim fit considering activity which will be worn as fall/winter physical education uniforms. Design 1 uses ottoman functional knit as a fabric material which is not only students favorite but also good in both flexibility and warmth. Top with style of high-neckline collar and full open zip-up is simplified with the incision lines and detail. It is a set-in sleeve design in which blue and yellow collars signifying school color are properly placed along with the incision lines in harmony.

A Study on the 1-Way FSI Analysis for Shutter of Side Jet Thruster (측추력기 Shutter의 단방향 유체-구조 연성해석에 관한 연구)

  • Ko, Jun Bok;Seo, Min Kyo;Lee, Kyeong Ho;Baek, Ki Bong;Cho, Seung Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.12
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    • pp.1359-1365
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    • 2014
  • In this study, 1-way fluid structure interaction analysis(FSI) for the shutter, component of side jet thruster was performed to evaluate the safety. Driving torque to open nozzle, thermal and high pressure load of hot gas was applied to shutter. Thus, the shutter must be designed to endure this load during combustion. We carried out computational fluid dynamics analysis to obtain the pressure, temperature, and heat transfer coefficient of hot gas of side jet thruster. We then used the data as the load condition for a thermal structural analysis using a mapping method. The locations with the maximum stress and temperature distributions were found. We compared the maximum stress with the tensile stress of shutter material according to temperature to evaluate the safety. We also analyzed the radial deformation of the shutter to set the proper interface gap with the side jet thruster parts.

A Critical Evaluation of the Concept and Writing of Learning Outcomes (학습성과의 개념과 작성에 대한 탐구)

  • Lee, Dong Yub;Yang, Eunbae B.
    • Korean Medical Education Review
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    • v.18 no.3
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    • pp.125-131
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    • 2016
  • Recent changes in educational paradigms that emphasize the performance or outcomes of education are redefining how learning objectives are being described as 'learning outcomes' in various academic disciplines. Medical education is not an exception to this trend. However, it has come to our attention that the key concepts and appropriate descriptions of learning outcomes have not been well understood among educators and that this lack of understanding has hindered our efforts to implement the practice in the field. This study aims to provide a direction to establish and describe learning outcomes by examining previous studies that have focused on setting learning objectives as well as learning outcomes. Setting and describing learning outcomes starts from reflection on the approach of behavioral learning objectives, which overemphasizes learner's acquired knowledge, skills, and attitude in each classroom rather than actual performance. On the other hand, the learning outcome approach focuses on what the learner is able to do as a result of a learning experience. This approach is more learner-friendly and encourages students to lead and be responsible for their learning process. Learning outcomes can best be described when the relevance of actual contexts and the hierarchy of learning objectives are considered. In addition, they should be in the form of context, task, performance, and level, as well as be planned with proper assessment and feedback procedures. When these conditions are met, the learning outcome approach is beneficial to students as it presents a curriculum that is more open to learners. Despite these advantages of the learning outcome approach, there is a possible concern that setting the learning outcomes and describing them can restrict evaluation to lower cognitive skills if the concept of learning outcome is narrowly interpreted or is set too low. To avoid such narrow applications, it is important for educators to understand the comprehensiveness of the learning outcome setting and to consider long-term outcomes embedded in an organizational vision rather than only short-term behavioral outcomes.

A Static Analyzer for Detecting Memory Leaks based on Procedural Summary (함수 요약에 기반한 메모리 누수 정적 탐지기)

  • Jung, Yung-Bum;Yi, Kwang-Keun
    • Journal of KIISE:Software and Applications
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    • v.36 no.7
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    • pp.590-606
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    • 2009
  • We present a static analyzer that detects memory leaks in C programs. It achieves relatively high accuracy at a relatively low cost on SPEC2000 benchmarks and several open-source software packages, demonstrating its practicality and competitive edge against other reported analyzers: for a set of benchmarks totaling 1,777 KLOCs, it found 332 bugs with 47 additional false positives (a 12.4% false-positive ratio), and the average analysis speed was 720 LOC/sec. We separately analyze each procedure's memory behavior into a summary that is used in analyzing its call sites. Each procedural summary is parameterized by the procedure's call context so that it can be instantiated at different call sites. What information to capture in each procedural summary has been carefully tuned so that the summary should not lose any common memory-leak-related behaviors in real-world C program. Because each procedure is summarized by conventional fixpoint iteration over the abstract semantics ('a la abstract interpretation), the analyzer naturally handles arbitrary call cycles from direct or indirect recursive calls.