• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.303-304
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• 2006

The mechanical properties of ferrous powder metallurgy (P/M) materials are directly related to their microstructure. Ferrous P/M materials with sufficient hardenability will develop microstructures containing significant percentages of martensite in the as-sintered condition. Recently, sinter-hardening has developed into a highly cost effective production method through hardened P/M parts without the need for additional heat-treatments. This paper reviews the advances of sinter-hardening as well as some key processing parameters such as sintering temperature, cooling rate, tempering required to produce high quality sinter-hardened components. Specific topics including effect of alloying elements, alloying methods, and the Characterization and observation of microstructure are discussed.

• ETRI Journal
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• v.25 no.2
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• pp.121-132
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• 2003

To enhance the productivity of software development and accelerate time to market, software developers have recently paid more attention to a component-based development (CBD) approach due to the benefits of component reuse. Among CBD processes, the identification of reusable components is a key but difficult process. Currently, component identification depends mainly on the intuition and experience of domain experts. In addition, there are few systematic methods or tools for component identification that enable domain experts to identify reusable components. This paper presents a systematic method and its tool called a component identifier that identifies software components by using object-oriented domain information, namely, use case models, domain object models, and sequence diagrams. To illustrate our method, we use the component identifier to identify candidates of reusable components from the object-oriented domain models of a banking system. The component identifier enables domain experts to easily identify reusable components by assisting and automating identification processes in an earlier development phase.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1513-1525
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• 2016

Rapid and accurate phase synchronization is critical for the reliable control of grid-tied inverters. However, the commonly used software phase-locked loop methods do not always satisfy the need for high-speed and accurate phase synchronization under severe grid imbalance conditions. To address this problem, this study develops a novel open-loop phase locking scheme based on a synchronous reference frame. The proposed scheme is characterized by remarkable response speed, high accuracy, and easy implementation. It comprises three functional cascaded blocks: fast orthogonal signal generation block, fast fundamental-frequency positive sequence component construction block, and fast phase calculation block. The developed virtual orthogonal signal generation method in the first block, which is characterized by noise immunity and high accuracy, can effectively avoid approximation errors and noise amplification in a wide range of sampling frequencies. In the second block, which is the foundation for achieving fast phase synchronization within 3 ms, the fundamental-frequency positive sequence components of unsymmetrical grid voltages can be achieved with the developed orthogonal signal construction strategy and the symmetrical component method. The real-time grid phase can be consequently obtained in the third block, which is free from self-tuning closed-loop control and thus improves the dynamic performance of the proposed scheme. The proposed scheme is adaptive to severe unsymmetrical grid voltages with sudden changes in magnitude, phase, and/or frequency. Moreover, this scheme is able to eliminate phase errors induced by harmonics and random noise. The validity and utility of the proposed scheme are verified by the experimental results.

• Journal of Life Science
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• v.29 no.7
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• pp.817-823
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• 2019

Immune system provides defense integrity of body against external invaders. In order to accomplish the important defending role immune system is composed of many different components which are regenerated continuously during lifespan. The key components are professional killing cells such as macrophage, neutrophil, natural killer cell, and cytotoxic T cell and professional blocking molecule, antibody, which is produced by plasma cell, the terminal differentiated B cell. Immune response is orchestrated harmoniously by all these components mediated through antigen presenting cells such as dendritic cells. Immune responses can be divided into two ways: innate immune response and adaptive immune response depending on induction mechanism. Aging is a broad spectrum of physiological changes. Likewise other physiological changes, the immune components and responses are wane as aging is progressing. Immune responses become decline and dysregulating, which is called immunosenescense. Immune components of both innate and adaptive immune response are affected as aging progresses leading to increased vulnerability to infectious diseases. Numbers of immune cells and amounts of soluble immune factors were decreased in aged animal models and human and also functional and structural alterations in immune system were reduced and declined. Cellular intrinsic changes were discovered as well. Recent researches focusing on aging have been enormously growing. Many advanced tools were developed to bisect aging process in multi-directions including immune system area. This review will provide a broad overview of aging-associated changes of key components of immunity.

• Journal of Ginseng Research
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• v.42 no.2
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• pp.149-157
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• 2018

Background: Panax notoginseng leaves (PNL) exhibit extensive activities, but few analytical methods have been established to exclusively determine the dammarane triterpene saponins in PNL. Methods: Ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC/Q-TOF MS) and HPLC-UV methods were developed for the qualitative and quantitative analysis of ginsenosides in PNL, respectively. Results: Extraction conditions, including solvents and extraction methods, were optimized, which showed that ginsenosides Rc and Rb3, the main components of PNL, are transformed to notoginsenosides Fe and Fd, respectively, in the presence of water, by removing a glucose residue from position C-3 via possible enzymatic hydrolysis. A total of 57 saponins were identified in the methanolic extract of PNL by UPLC/Q-TOF MS. Among them, 19 components were unambiguously characterized by their reference substances. Additionally, seven saponins of PNL-ginsenosides Rb1, Rc, Rb2, and Rb3, and notoginsenosides Fc, Fe, and Fd-were quantified using the HPLC-UV method after extraction with methanol. The separation of analytes, particularly the separation of notoginsenoside Fc and ginsenoside Rc, was achieved on a Zorbax ODS C8 column at a temperature of $35^{\circ}C$. This developed HPLC-UV method provides an adequate linearity ($r^2$ > 0.999), repeatability (relative standard deviation, RSD < 2.98%), and inter- and intraday variations (RSD < 4.40%) with recovery (98.7-106.1%) of seven saponins concerned. This validated method was also conducted to determine seven components in 10 batches of PNL. Conclusion: These findings are beneficial to the quality control of PNL and its relevant products.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.85-92
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• 2016

The operating temperature of VHTR components is much higher than that of conventional PWR due to high core outlet temperature of VHTR. Material requirements and technical issues of VHTR reactor components which are mainly dominated by high temperature service condition were discussed. The codification effort for high temperature material and design methodology are explained. The design class for VHTR components are classified as class A or B according to the recent ASME high temperature reactor design code. A separation of thermal boundary and pressure boundary is used for VHTR components as an elevated design solution. Key design characteristics for reactor pressure vessel, control rod, reactor internals, graphite reflector, circulator and intermediate heat exchanger were analysed. Thermo-mechanical analysis of the process heat exchanger, which was manufactured for test, is presented as an analysis example.

• Corrosion Science and Technology
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• v.12 no.3
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• pp.142-148
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• 2013

Safety is a major concern in Nuclear Power Plants (NPPs). Piping systems in NPPs are very complex and composed of many components such as tees, elbows, expanders and straight pipes. The high pressure and high temperature water flows inside piping components. As high speed water flows inside piping, the pipe wall thinning occurs in various reasons such as FAC (Flow Accelerated Corrosion), LDIE (Liquid Droplet Impingement Erosion) and Flashing. To inspect the wall thinning phenomenon and protect the piping from damages, piping components are checked by UT measurement in every overhaul. During every overhaul, approximately 200~300 components (40,000~60,000 UT data) are examined in NPPs. There are some methods from EPRI for evaluating wear rate of components. However, only few studies have been conducted to find out the raw data reliability for the wear rate evaluation. Securing the reliable raw data is the key factor for a reasonable evaluation. This paper suggests the reliability analysis method for the repeatedly measured data for wear rate evaluation.

• Journal of information and communication convergence engineering
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• v.17 no.2
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• pp.149-160
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• 2019

Web applications typically interact with databases. Therefore, it is very crucial to understand which web components access which database resources when maintaining web apps. Existing research identifies interactions between Java web components, such as JavaServer Pages and servlets but does not extract dependencies between the web components and database resources, such as tables and attributes. This paper proposes a dynamic analysis of Java web apps, which extracts such dependencies from a Java web app and represents them as a graph. The key responsibility of our analysis method is to identify when web components access database resources. To fulfill this responsibility, our method dynamically observes the database-related objects provided in the Java standard library using the proxy pattern, which can be applied to control access to a desired object. This study also experiments with open source web apps to verify the feasibility of the proposed method.

• Biomedical Science Letters
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• v.20 no.1
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• pp.1-7
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• 2014

RNA granules such as Stress Granules (SG) and P-Bodies (PB) are aggregates of translationally stalled messenger ribonucleoprotein (mRNP) complexes induced by a wide range of stresses. Over the past decade, extensive studies described key components of RNA granules, their molecular interactions and signaling pathways require for their assembly and disassembly. However, researches defining their exact roles under stress conditions have not been performed so far, although several studies suggested their roles in neurodegenerative diseases recently. In this review, we provide an introduction about their basic properties, key components, and the dynamic nature for their assembly.

• Asian Journal of Innovation and Policy
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• v.7 no.1
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• pp.30-54
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• 2018

Tech start-ups and their ecosystems are gaining increasing prominence globally and so are in India, due to their potential to contribute to employment generation, innovations, productivity, national income and exports. Against this backdrop, this article analyzes the key characteristics of tech start-ups relative to traditional start-ups and modern start-ups in India. Further, the salient features of tech start-up promotion policies initiated by the government of India and government of Karnataka as well as the current regional and sectoral distribution of start-ups is elucidated. Subsequently, the structure and components of entrepreneurial ecosystems currently under evolution in the metro cities of India are examined. Finally, the key factors contributing to the growth of different ecosystem components and its implications for the future growth of tech start-ups are outlined.