• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.1-9
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• 2007

OSP(organic solderability preservatives) finish has been considered as a very effective process for substituting the metal surface treatment of Ni/Au finish because of lower cost, interface property and environmental issue of OSP finish. However, the discoloration of OSP layer is formed during assembly process consisting of various steps of temperature. The causes of discoloration and the characterization of solder joint were investigated with a degree of discoloration and the assembly process of OSP finished products, which was also compared statistically with that of conventional Ni/Au finished products. As the results, the solution of process trouble for OSP finished products is able to be offered.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.613-619
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• 2003

The polyketide backbone of rifamycin B is assembled by the type I rifamycin polyketide synthase (PKS) encoded by the rifA-rifE genes. In order to produce novel analogs of rifamycin via engineering of the PKS genes, inactivation of the ${\beta}-ketoacyl:acyl$ carrier protein reductase (KR) domain in module 8 of rifD, by site-specific mutagenesis of the NADPH binding site, was attempted. Module 8 contains a nonfunctional dehydratase (DH) domain and a functional KR domain that is involved in the reduction of the ${\beta}-carbonyl$ group, resulting in the C-21 hydroxyl of rifamycin B. This mutant strain produced linear polyketides, from tetraketide to octaketide, which were also produced by a rifD-disruption mutant as a consequence of premature termination of the polyketide assembly. Another attempt to replace the DH domain of module 7, which has been considered nonfunctional, with a functional homolog derived from module 7 of rapamycin-producing PKS also resulted in the production of linear polyketides, including the heptaketide intermediate and its precursors. Premature release of the carbon chain assembly intermediates is an unusual property of the rifamycin PKS. that is not seen in other PKSs such as the erythromycin PKS.

• Macromolecular Research
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• v.16 no.2
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• pp.113-119
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• 2008

A series of amphiphilic dendrons n-18 (n: generation number, 18: octadecyl chain) based on an aliphatic polyether denderitic core and octadecyl peripheries were synthesized using a convergent dendron synthesis consisting of a Williamson etherification and hydroboration/oxidation reactions. This study investigated their thermal and self-assembling behavior in the solid state using differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) absorption spectroscopy, and small angle X-ray scattering (SAXS). DSC indicated that the melting transition and the corresponding heat of the fusion of the octadecyl chain decreased with each generation. FT-IR showed that the hydroxyl focal groups were hydrogen-bonded with one another in the solid state. DSC and FT-IR indicated microphase-separation between the hydrophilic dendritic cores and hydrophobic octadecyl peripheries. SAXS data analysis in the solid state suggested that the lower-generation dendrons 1-18 and 2-18 self-assemble into lamellar structures based upon a bilayered packing of octadecyl peripheries. In contrast, the analyzed data of higher-generation dendron 3-18 is consistent with 2-D oblique columnar structures, which presumably consist of elliptical cross sections. The data obtained could be rationalized by microphase-separation between the hydrophilic dendritic core and hydrophobic octadecyl peripheries, and the degree of interfacial curvature associated with dendron generation.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.495-500
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• 2019

When a new fuel is developed, various mechanical properties are absolutely necessary for a safety analysis of the fuel for the licensing and prediction of its mechanical behavior during operation and accident conditions. In this paper, a mechanically equivalent surrogate plate of U-Mo dispersion fuel is presented using tungsten, substitute material of U-Mo particle. A surrogate plate, composed of tungsten/aluminum dispersion meat and aluminum alloy cladding, is manufactured with the same fabrication process with that of fuel plate except that a tungsten powder is used instead of U-Mo powder. A modal test showed that the surrogate plate and fuel plate have similar dynamic characteristics, and a tensile test demonstrated the similarity of the material property up to the yield strength range. The conducted tests proved that the surrogate tungsten plate has equivalent mechanical behaviors with that of a fuel plate, which leads to the acceptable use of a surrogate fuel assembly using tungsten/aluminum dispersion meat in various mechanical tests. The surrogate fuel assembly can be utilized for various out-of-pile characteristic tests, which are necessary for the licensing achievement of a research reactor that uses U-Mo dispersion fuel as a driver.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.148-165
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• 2012

Applying maintenance simulation using virtual mockup in product design phase enables maintainability test before prototyping physical products, and it is expected to reduce product development costs. The simulation results can be reused as contents of service manuals and RAM (Reliability, Availability, Maintainability) analysis data. Maintenance simulation should provide realistic representation of physical property of virtual product, assembly relation between parts and manipulation process to verify feasibility of product design. The simulation system should be extended to collaborative virtual environment to perform collaborative maintenance procedures. In this paper, the three layered system architecture and the physics based collaborative interaction technique are proposed to extend current maintenance simulation into collaborative virtual environment. The proposed system was implemented as ViMMS (Virtual Mockup Maintenance Simulation system), and compared with case study results of VADE (Virtual Assembly Design Environment). As a result, the ViMMS encompassed broader range of maintenance tasks by using physics based collaborative interaction technique.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.109-114
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• 2016

Monodispersed $ZnGa_2O_4$ microspheres were synthesized by a facile two-step process consisting of a solvothermal method and calcination process. The prepared monodispersed $ZnGa_2O_4$ microspheres were aggregated into 3D microstructures by self-assembly with a large number of small $ZnGa_2O_4$ particles generated in nucleation. This nucleation and self-assembly making hierarchical microstructures were depended on the concentration of PEG (polyethylene glycol) due to CAC (critical aggregation concentration) theory. And also we controlled the amount of zinc acetate to make pure $ZnGa_2O_4$ phase. Additionally, to fix the optimized calcination condition, sample was characterized by TG-DTA to prove the thermal property in the calcination process and by FT-IR to identify the changes of functional group bonding between each element of the $ZnGa_2O_4$ precursor and oxide calcined at $900^{\circ}C$ for 1 h.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.4
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• pp.393-400
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• 2015

This study proposes a method to create and combine a superstructure module by parametric modeling, in order to improve the production efficiency of information model for modular steel bridge superstructure that can be used in planning, design and construction phase. Compound classification was performed in order to derive elements to apply the parametric modeling, and according to assembly condition, the classified elements were grouped into 13 types. In addition, three assembly conditions were derived for production of stable superstructure through combination of superstructure module, which is a production unit for modular steel bridge factory. Parameter that reflects assembly condition in compound shape when producing superstructure module through parametric modeling was deducted. Superstructure module compounds were produced according to type and parameter using interface generation based on Building Information Model(BIM) software that was developed in this study. The superstructure module produced reflects information to combine into a superstructure. To verify this, information model based on Industry Foundation Classes(IFC) was built and confirmed the application in production of superstructure by identifying the reflected property information.

• Smart Structures and Systems
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• v.3 no.2
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• pp.189-200
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• 2007

As a functional material, shape memory alloy (SMA) has attracted much attention and research effort to explore its unique properties and its applications in the past few decades. Some of its properties, in particular the electrical resistance (ER) based self-sensing property of SMA, have not been fully studied. Electrical resistance of an SMA wire varies during its phase transformation. This variation is an inherent property of the SMA wire, although it is highly nonlinear with hysteresis. The relationship between the displacement and the electrical resistance of an SMA wire is deterministic and repeatable to some degree, therefore enabling the self-sensing ability of the SMA. The potential of this self-sensing ability has not received sufficient exploration so far, and even the previous studies in literature lack generality. This paper concerns the utilization of the self-sensing property of a spring-biased Nickel-Titanium (Nitinol) SMA actuator for two applications: ER feedback position control of an SMA actuator without a position sensor, and estimation of the opening of a SMA actuated valve. The use of the self-sensing property eliminates the need for a position sensor, therefore reducing the cost and size of an SMA actuator assembly. Two experimental apparatuses are fabricated to facilitate the two proposed applications, respectively. Based on open-loop testing results, the curve fitting technique is used to represent the nonlinear relationships between the displacement and the electrical resistance of the two SMA wire actuators. Using the mathematical models of the two SMA actuators, respectively, a proportional plus derivative controller is designed for control of the SMA wire actuator using only electrical resistance feedback. Consequently, the opening of the SMA actuated valve can be estimated without using an extra sensor.

• Korean Journal of Heritage: History & Science
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• v.52 no.4
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• pp.78-103
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• 2019

The Conservation Decree of the Chosun Treasures Historic and Natural Monuments (hereinafter referred to as the Conservation Decree), which was enacted during the Japanese colonial period, was preserved in accordance with the provisions of article No. 100 of the constitutional law. However, legislative attempts were made to replace the Conservation Decree during the US military administration and early Korean Government. The first attempt was about the National Treasures Historic and Natural Monuments which were brought in by the Legislative Assembly of South Chosun (1947) during the US military administration. The second was a bill by the government for preservation of historical interests (1950), which was submitted to the National Assembly on March 15, 1950 (the so-called Preservation Act (1950)). These two bills were amended and supplemented on the basis of the existing contents of the Conservation Decree. Afterwards, from 1952 to 1960, the legislation of the Cultural Heritage Protection Act (1959) and the Cultural Heritage Bill (1960) were subsequently introduced and enacted. The government's attempt to enact such a cultural property bill was aimed at the legislature to replace the preservation order system that had been in effect since the Japanese colonial period. However, due to the political situation at the time, these laws did not reach final legislation. In October 1960, the government enacted the Regulations for the Preservation of Cultural Property, which was an administrative edict that was promulgated and enacted in November. This was the first official cultural property decree introduced by the Korean government. With the enactment and promulgation of the Cultural Heritage Protection Act in January 1962, Korea's judicial cultural property legislation was established, based on the Korean government's unremitting efforts and experience in legislation of cultural property. In that context, the Cultural Heritage Protection Act is a historical product. The Cultural Heritage Protection Act, which was enacted in 1962, is known to emulate or transplant Japan's Cultural Heritage Protection Act (1950). It was not fully recognized that it was an extension of the Korean government's legislative process of cultural property during the period of 1945-1960. Therefore, it is important to examine the legislative process of cultural property from 1945 to 1960 to understand the background of enacting the Cultural Heritage Protection Act in 1962 along with the establishment of the Korean Cultural Property Law.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.15-19
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• 2006

A ferredoxin adsorbed hetero self-assembled layer was fabricated on chemically modified Au substrate, 4-Aminothiophenol (4-ATP) was deposited onto Au substrate and then N-succinimidyl-3-[2-pyridyldithio] propionate (SPDP) was adsorbed on the 4-ATP layer, since SPDP was used as a bridging molecule for ferredoxin adsorption, Ferredoxin/SPDP/4-ATP structured hetero layer was constructed because of strong chemical binding of ferredoxin, SPDP, and 4-ATP, The surface of the ferredoxin-adsorbed SPDP/4-ATP layer was observed by scanning tunneling microscopy, The hetero film formation was verified by surface plasmon resonance measurement. The current flow and rectifying property based on the scanning tunneling spectroscopy I-V characteristics was achieved in the proposed hetero layer. Thus, the hetero layer structure of ferredoxin functioned as a molecular diode with rectifying property, The proposed molecular diode can be usefully applied for the development of molecular scale electronic devices.