• Coupled systems mechanics
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• 제10권1호
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• pp.39-60
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• 2021

The present paper is concerned with the study of nonlinear ultrasonic waves in a magneto thermo (MT) elastic armchair single-walled carbon nanotube (ASWCNT) resting on polymer matrix. The analytical formulation is developed based on Eringen's nonlocal elasticity theory to account small scale effect. After developing the formal solution of the mathematical model consisting of partial differential equations, the frequency equations have been analyzed numerically by using the nonlinear foundations supported by Winkler-Pasternak model. The solution is obtained by ultrasonic wave dispersion relations. Parametric work is carried out to scrutinize the influence of the non local scaling, magneto-mechanical loadings, foundation parameters, various boundary condition and length on the dimensionless frequency of nanotube. It is noticed that the boundary conditions, nonlocal parameter, and tube geometrical parameters have significant effects on dimensionless frequency of nano tubes. The results presented in this study can provide mechanism for the study and design of the nano devices like component of nano oscillators, micro wave absorbing, nano-electron technology and nano-electro- magneto-mechanical systems (NEMMS) that make use of the wave propagation properties of armchair single-walled carbon nanotubes embedded on polymer matrix.

• IMMUNE NETWORK
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• 제16권5호
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• pp.281-285
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• 2016

CD4⁺ regulatory T cells (Tregs) are essential for normal immune surveillance, and their dysfunction can lead to the development of autoimmune diseases, such as type-1 diabetes (T1D). T1D is a T cell-mediated autoimmune disease characterized by islet b cell destruction, hypoinsulinemia, and severely altered glucose homeostasis. Tregs play a critical role in the development of T1D and participate in peripheral tolerance. Pluripotent stem cells (PSCs) can be utilized to obtain a renewable source of healthy Tregs to treat T1D as they have the ability to produce almost all cell types in the body, including Tregs. However, the right conditions for the development of antigen (Ag)-specific Tregs from PSCs (i.e., PSC-Tregs) remain undefined, especially molecular mechanisms that direct differentiation of such Tregs. Auto Ag-specific PSC-Tregs can be programmed to be tissue-associated and infiltrate to local inflamed tissue (e.g., islets) to suppress autoimmune responses after adoptive transfer, thereby avoiding potential overall immunosuppression from non-specific Tregs. Developing auto Ag-specific PSC-Tregs can reduce overall immunosuppression after adoptive transfer by accumulating inflamed islets, which drives forward the use of therapeutic PSC-Tregs for cell-based therapies in T1D.

• 대한지리학회지
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• 제29권2호
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• pp.166-182
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• 1994

본 연구에서는 고등학교 지리수업이 안고 있는 대학입시 지도와의 관련성, 기초개 념의 중복성, 수업시간의 제한 등 세가지 문제점을 해결하기 위해 수업을 구조화하여 고등 사고 기능을 기를 수 있는 수업을 설계하고자 하였다. 그러기 위해서 행동이론과 구조분석 을 통합한 지리수업 설계에 대하여 단계적으로 다음과 같이 정리해 볼 수 있다. 우선, 제 1 단계로서, 학습자는 경험적인 현상의 기술인 자료를 조사하고, 과학자의 시점에 따라서 객관 성과 정확성을 유지하면서, 가설-검증의 과정을 통하여 說明的 知識에 이른다, 제 2단계에 서는, 추론적인 진술에 대한 비판적 사고를 통하여 공간구조를 분석하는 것으로 槪念的 知 識을 이론적으로 설명한다. 제 3단계에서는, 지역주민의 행위를 둘러싸고 있는 상황을 파악 하기 위해 자료를 비판적으로 다시 검토하여 사회 제도 간의 관계까지 實踐的 解釋에 이른 다. 제4단계로서는, 정보를 활용하는 능력을 기르기 위해 事例地域 學習에 대해 주체적으로 참여한다. 따라서, 행동이론과 구조분석의 통합을 통한 지리수업의 설계에서 본다면, 수업이 구조화되고 실증론에 대한 인식론적 입장에서 전개될 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.478-483
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• 2001

We experimentally attempted to understand the vibration characteristics of a flexible pipe excited by vortex shedding. This has been extensively studied in the past decades (For example, see ［2-9］). However, there are still areas that need more study. One of them is to study the relation between spatial characteristics of a flow induced vibrating pipe, such as its length, the distribution of wave number, and frequency responses. A non-linear mechanism between the responses of in-line and cross-flow directions is also an area of interests, if the pipe is relatively long so that structural modal density is reasonably high. In order to investigate such areas, two kinds of instrumented pipe were designed. The instrumented pipes, of which the lengths are equally 6m, are wound with rubber and silicon tape in different ways, having different vortex shedding conditions. One has uniform cross-section of diameter of 26. 7mm, and the other has equally spaced by 4 sub-sections, which are composed of different diameters of 75.9, 61.1, 45.6 and 26.7mm. Both pipes are towed in a water tank (200m ${\times}$ 16m ${\times}$ 7m) so that they experienced different vortex shedding excitations. The towing pipe experiments exhibit several valuable features. One of them is that the natural frequencies and their corresponding strain mode shapes dominate the strain response of the uniform pipe. However, for those of non-uniform pipe, the responses are more likely local and many modes participate in it.

• Journal of Advanced Marine Engineering and Technology
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• 제30권5호
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• pp.572-579
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• 2006

Accurate heat release analysis based on the cylinder pressure trace is important for evaluating combustion process of diesel engines. However, traditional single-zone heat release models (SZM) have significant limitations due mainly to their simplified assumptions of uniform charge and homogeneity while neglecting local temperature distribution inside cylinder during combustion process. In this study, a heat release analysis based on single-zone model has been evaluated by comparison with computational simulation result using Fire-code, which is based on multidimensional model (MDM). The limitations of the single-zone assumption have been estimated, To overcome these limitations, an improved model that includes the effects of spatial non-uniformity has been applied. From this improved single-zone heat release model (Improved-SZM), two effective values of specific heat ratios, denoted by ${\gamma}_V$ and ${\gamma}_H$ in this study, have been introduced. These values are formulated as the function of charge temperature changing rate and overall equivalence ratio. Also, it is applied that each equation of ${\gamma}_V$ and ${\gamma}_H$ has respectively different slopes according to several meaningful periods during combustion progress. The heat release analysis results based on improved single-zone model gives a good agreement with FIRE-code results over the whole range of operating conditions of target engine, Hyundai HiMSEN H21/32.

• Smart Structures and Systems
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• 제6권3호
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• pp.197-209
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• 2010

The structural state of a bridge is currently examined by visual inspection or by wired sensor techniques, which are relatively expensive, vulnerable to inclement conditions, and time consuming to undertake. In contrast, wireless sensor networks are easy to deploy and flexible in application so that the network can adjust to the individual structure. Different sensing techniques have been used with such networks, but the acoustic emission technique has rarely been utilized. With the use of acoustic emission (AE) techniques it is possible to detect internal structural damage, from cracks propagating during the routine use of a structure, e.g. breakage of prestressing wires. To date, AE data analysis techniques are not appropriate for the requirements of a wireless network due to the very exact time synchronization needed between multiple sensors, and power consumption issues. To unleash the power of the acoustic emission technique on large, extended structures, recording and local analysis techniques need better algorithms to handle and reduce the immense amount of data generated. Preliminary results from utilizing a new concept called Acoustic Emission Array Processing to locally reduce data to information are presented. Results show that the azimuthal location of a seismic source can be successfully identified, using an array of six to eight poor-quality AE sensors arranged in a circular array approximately 200 mm in diameter. AE beamforming only requires very fine time synchronization of the sensors within a single array, relative timing between sensors of $1{\mu}s$ can easily be performed by a single Mote servicing the array. The method concentrates the essence of six to eight extended waveforms into a single value to be sent through the wireless network, resulting in power savings by avoiding extended radio transmission.

• BMB Reports
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• 제35권2호
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• pp.155-164
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• 2002

The structural aspects of ervatamin B have been studied in different types of alcohol. This alcohol did not affect the structure or activity of ervatamin B under neutral conditions. At a low pH (3.0), different kinds of alcohol have different effects. Interestingly, at a certain concentration of non-fluorinated, aliphatic, monohydric alcohol, a conformational switch from the predominantly $\alpha$-helical to $\beta$-sheeted state is observed with a complete loss of tertiary structure and proteolytic activity. This is contrary to the observation that alcohol induces mostly the $\alpha$helical structure in proteins. The O-state of ervatamin B in 50% methanol at pH 3.0 has enhanced the stability towards GuHCl denaturation and shows a biphasic transition. This suggests the presence of two structural parts with different stabilities that unfold in steps. The thermal unfolding of ervatamin B in the O-state is also biphasic, which confirms the presence of two domains in the enzyme structure that unfold sequentially. The differential stabilization of the structural parts may also be a reflection of the differential stabilization of local conformations in methanol. Thermal unfolding of ervatamin B in the absence of alcohol is cooperative, both at neutral and low pH, and can be fitted to a two state model. However, at pH 2.0 the calorimetric profiles show two peaks, which indicates the presence of two structural domains in the enzyme with different thermal stabilities that are denatured more or less independently. With an increase in pH to 3.0 and 4.0, the shape of the DSC profiles change, and the two peaks converge to a predominant single peak. However, the ratio of van't Hoff enthalpy to calorimetric enthalpy is approximated to 2.0, indicating non-cooperativity in thermal unfolding.

• 대한전자공학회논문지SP
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• 제42권6호
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• pp.195-202
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• 2005

적응 분할 알고리즘은 국부 비 균질 영상에서 효율적인 표적 탐지를 위해 사용된다. 지금까지 영상 분할에 여러 가지 적응방법이 제안되었다. 하지만 이들 알고리즘이 레이다 표적 탐지에 바로 적용하기는 어려운데 이는, 레이다 자체 신호 특성 때문이다. 일반적으로 레이다 표적은 배경신호에 비해 상대적으로 적은 도수 함수를 갖고 있으며, 배경 분포는 외부환경에 따라 다양한 형태를 갖는다. 본 논문에서는 도수함수의 최대 값에서 우측 하향 직선인 히스토그램 현을 이용한 적응 표적분할 알고리즘을 제안한다. 제안한 방식은 임계값 탐색에 사용되는 적용 현이 외부환경조건에 영향을 적게 받음으로 인해 다양한 레이다 환경에 최적인 임계 값을 선택한다. 시뮬레이션 결과, 제안한 알고리즘이 기존 표적분할알고리즘인 전역 임계 값 방법 및 분포 중앙값 추정방식에 비해 탐지성능측면에서 우수함을 보였다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제25권3호
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• pp.263-275
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• 2022

Purpose: The present international survey among healthcare providers aimed to collect data on theoretical knowledge and clinical practices in the diagnosis and management of cow's milk protein allergy (CMPA) and lactose intolerance (LI) in infants. Methods: A global survey was conducted in several countries with diverse health care settings. The survey consisted of multiple-choice questions in 3 main domains: (1) understanding and clinical practices around CMPA and LI; (2) case scenarios; and (3) disease-specific knowledge and potential educational needs. Results: Responses were available from 1,663 participants. About 62% of respondents were general practitioners or general pediatricians, and the remainder were pediatric allergists/gastroenterologists (18%) or other health practitioners (20%). The survey identified knowledge gaps regarding the types of CMPA (IgE-mediated vs. non-IgE-mediated) and the clinical overlap with LI. The survey suggested diverse clinical practices regarding the use of hypoallergenic formulas, as well as misconceptions about the prebiotic benefits of lactose in extensively hydrolyzed formulas in non-breastfed infants with CMPA. Responses to the two case scenarios highlighted varying levels of awareness of the relevant clinical practice guidelines. While respondents generally felt confident in managing infants with CMPA and LI, about 80% expressed an interest for further training in this area. Conclusion: The current survey identified some knowledge gaps and regional differences in the management of infants with CMPA or LI. Local educational activities among general and pediatric healthcare providers may increase the awareness of clinical practice guidelines for the diagnosis and treatment of both conditions and help improve clinical outcomes.

• 한국농촌건축학회논문집
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• 제25권1호
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• pp.1-8
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• 2023

This is a case study of private sector's development of long-term unexecuted urban parks in Pohang through a special act, which provides a guideline of 30% of land for non-park while 70% of land for park. The strategy has a lot of validity in many respects along with the urban planning sunset system, but even with the special act it would not easy to be implemented in Pohang, where the guideline has been modified to 20% for non-park, mostly multi-family housing projects while 80% for park. Thus, participation of private companies would be discouraged due to low commercial validity. Also, there would exist various risks because the project would be completed through a long-term decision-making and execution process. Thus, this study argues that it would be better for Pohang to follow the original guideline of the government for better implementation of the projects, along with preparation of a law with which the government be able to recoup excess profits when too much profits would be given to private developers. For the project implemented smoothly, it is also important to understand local housing market and fluctuating economic conditions, and to prepare various incentives for private companies. In addition, to secure publicity, guidelines on the level of publicity of the project should be prepared through negotiation by parties to prevent the project being discouraged too much.