• 전기의세계
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• v.25 no.5
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• pp.63-69
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• 1976

Among various types of photo-electric energy conversion element which can transfer solar energy into electric energy through the photo voltaic effect, Si solar cells were investigated on photoelectric characteristics, improvements of its efficiency and economical evaluation for its production cost. To study the above subjects, we decided best conditions on fabricating of thin film Si solar cell by epitaxial growth and knew that the thin solar cell by epitaxial growth was more efficient than that by diffusion process. And also higher photo voltaic output was obtained as a effect of SiO as antireflection coating by several methods, i.e. vacuum evaporating techniques of electrode to decrease the contact resistance and to form best ohmic contact, and concentration techniques of sun's ray by lenz or both-sided illumination through special structure for reflection using mirrors.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.4
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• pp.176-179
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• 2001

Iron oxide powders were prepared under high temperature (up to $175^{\circ}C$) and pressure conditions( up to 129 pasi) by precipitation from metal nitrates with aqueous potassium hydroxide. Various types of iron oxide powders were obtained at different conditions. The size and the shape of the particles can be controlled as afunction of starting solution pH. The average particles size of the synthesized iron oxide powders increased, the particle shapes of the powders became fibrous, and the crystalline phase of the powder changes from iron oxide to iron hydroxide with increasing solution pH. The effects of synthesis parameters are discussed.

• Nuclear Engineering and Technology
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• v.46 no.1
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• pp.55-62
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• 2014

A method for estimating software reliability for nuclear safety software is proposed in this paper. This method is based on the software reliability growth model (SRGM), where the behavior of software failure is assumed to follow a non-homogeneous Poisson process. Two types of modeling schemes based on a particular underlying method are proposed in order to more precisely estimate and predict the number of software defects based on very rare software failure data. The Bayesian statistical inference is employed to estimate the model parameters by incorporating software test cases as a covariate into the model. It was identified that these models are capable of reasonably estimating the remaining number of software defects which directly affects the reactor trip functions. The software reliability might be estimated from these modeling equations, and one approach of obtaining software reliability value is proposed in this paper.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.1
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• pp.17-29
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• 2016

Though there is an abundant supply of nitrogen in the atmosphere, it cannot be used directly by the biological systems since it has to be combined with the element hydrogen before their incorporation. This process of nitrogen fixation ($N_2$-fixation) may be accomplished either chemically or biologically. Between the two elements, biological nitrogen fixation (BNF) is a microbiological process that converts atmospheric di-nitrogen ($N_2$) into plant-usable form. In this review, the genetics and mechanism of nitrogen fixation including genes responsible for it, their types and role in BNF are discussed in detail. Nitrogen fixation in the different agricultural systems using different methods is discussed to understand the actual rather than the potential $N_2$-fixation procedure. The mechanism by which the diazotrophic bacteria improve plant growth apart from nitrogen fixation such as inhibition of plant ethylene synthesis, improvement of nutrient uptake, stress tolerance enhancement, solubilization of inorganic phosphate and mineralization of organic phosphate is also discussed. Role of diazotrophic bacteria in the enhancement of nitrogen fixation is also dealt with suitable examples. This mini review attempts to address the importance of diazotrophic bacteria in nitrogen fixation and plant growth improvement.

• Journal of Sensor Science and Technology
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• v.29 no.3
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• pp.187-193
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• 2020

Ultraviolet (UV) sensors are widely applied in industrial and military fields such as environmental monitoring, medicine and astronomy. Zinc oxide (ZnO) is considered as one of the promising materials for UV sensors because of its ease of fabrication, wide bandgap (3.37 eV) and high chemical stability. In this study, we used the hydrothermal growth of ZnO to form two types of ZnO nanostructures (Nanoflower and nanorod) and applied them to a UV sensor. To improve the performance of the UV sensor, the hydrothermal growth was used in a two-step process for fabricating ZnO hierarchical nanostructures. The fabricated ZnO hierarchical nanostructure improved the performance of the UV sensor by increasing the ratio of volume to surface area and the number of nanojunctions compared to one-step hydrothermal grown ZnO nanostructure. The UV sensor based on the ZnO hierarchical nanostructure had a maximum photocurrent of 44 ㎂, which is approximately 3 times higher than that of a single nanostructure. The UV sensor fabrication method presented in this study is simple and based on the hydrothermal solution process, which is advantageous for large-area production and mass production; this provides scope for extensive research in the field of UV sensors.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.242-245
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• 2002

Authentication protocol as a part of security system has been growth rapidly since it was known that sending clear text password in the network is unsecured. Many protocols could be noted proposed to strengthen the authentication process. In 1985 an attempt to safeguard network services within Athena project resulting on the born of Kerberos 〔1〕〔8〕, one of the protocol that has a lot of attention from the research community. Several years later researchers were discovered some weaknesses carried by this protocol 〔2〕〔21〕. In 1992. EKE was introduced by Bellovin and Merrit. Since that time, many protocols introduced could be considered as its variant 〔5〕〔9〕〔13〕〔14〕. Some other protocols such as OKE〔5〕 and SRP〔18〕 although claimed different from EKE, they have the same basic mechanism in holding authentication process. Here, we explain the mechanism of those protocols, their strength and their weaknesses and shortcomings. Due to the limitations of the number of paper pages, only two types of authentication protocol can be explained here i.e EKE and SRP.

• Biomolecules & Therapeutics
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• v.28 no.6
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• pp.503-511
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• 2020

Autophagy is a major catabolic process that maintains cell metabolism by degrading damaged organelles and other dysfunctional proteins via the lysosome. Abnormal regulation of this process has been known to be involved in the progression of pathophysiological diseases, such as cancer and neurodegenerative disorders. Although the mechanisms for the regulation of autophagic pathways are relatively well known, the precise regulation of this pathway in the treatment of cancer remains largely unknown. It is still complicated whether the regulation of autophagy is beneficial in improving cancer. Many studies have demonstrated that autophagy plays a dual role in cancer by suppressing the growth of tumors or the progression of cancer development, which seems to be dependent on unknown characteristics of various cancer types. This review summarizes the key targets involved in autophagy and malignant transformation. In addition, the opposing tumor-suppressive and oncogenic roles of autophagy in cancer, as well as potential clinical therapeutics utilizing either regulators of autophagy or combinatorial therapeutics with anti-cancer drugs have been discussed.

• Molecules and Cells
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• v.24 no.2
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• pp.177-184
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• 2007

Approximately 200 individual skeletal elements, which differ in shape and size, are the building blocks of the vertebrate skeleton. Various features of the individual skeletal elements, such as their location, shape, growth and differentiation rate, are being determined during embryonic development. A few skeletal elements, such as the lateral halves of the clavicle and parts of the skull are formed by a process called intramembranous ossification, whereby mesenchymal cells differentiate directly into osteoblasts, while the majority of skeletal elements are formed via endochondral ossification. The latter process starts with the formation of a cartilaginous template, which eventually is being replaced by bone. This requires co-regulation of differentiation of the cell-types specific for cartilage and bone, chondrocytes and osteoblasts, respectively. In recent years it has been demonstrated that Wnt family members and their respective intracellular pathways, such as non-canonical and the canonical $Wnt/{\beta}$-catenin pathway, play important and diverse roles during different steps of vertebrate skeletal development. Based on the recent discoveries modulation of the canonical Wnt-signaling pathway could be an interesting approach to direct stem cells into certain skeletal lineages.

• Korean System Dynamics Review
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• v.6 no.2
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• pp.5-23
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• 2005

This paper investigates a dynamic mechanism underlying the process of knowledge creation and evolution with a focus on the SECI model(standing for Socialization, Externalization, Combination, Internalization) as proposed by Nonaka and Takeuchi(1991) and broadly accepted especially among the practitioners in knowledge management field. The SECI model provides with intuitive logic and clear delineation of knowledge types between the tacit and the explicit, and embodies an interaction dynamic. However explanations of the propelling forces for the knowledge transfer over the four quadrants of the model is yet to be made. And the transmission mechanisms are not prescribed though the model mentions knowledge is created and evolved in a spiral process. This paper, therefore attempts first to extend and elaborate it into a dynamic SECI model by identifying those propelling factors and their relationships(linkages) based on the systems thinking.

• Journal of the Korean Society of Costume
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• v.65 no.4
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• pp.19-30
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• 2015

In recent years, various studies about 'Biomorphic design' have been conducted and accelerated among many recent design concepts and methodology. Therefore, this study classifies the types of biomorphic fashion design based on literature review, and select biomorphic fashion designs in the latest fashion designer's collection. This study aimed to determine the types and characteristics of the biomorphic design in fashion design, and analyze the characteristics and the interpreted intrinsic meanings through Greimas Semiotic rectangle model based on the Binary-Opposition of meaning and Isotophy. As the result of analysis, biomorphic designs in fashion are classified as three types: 'representational imitation of form', 'technical imitation of functional features', and 'imitation of symbolic attribute'. 'Representational imitation of form' was derived from an organic design through atypical forms, repetition and extension of figurative forms of nature, and 'the functionalities of the nature' are interpreted as the feature to maintain the condition of the life itself and to attempt to regulate the status of self-autonomy. Lastly, 'the imitation of symbolic attributes' is designing the process of creation, growth, expansion and destruction from circulation of nature.