• Polymer(Korea)
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• v.30 no.2
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• pp.97-107
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• 2006

In spite of excellent thermomechanical performance the majority of aromatic polyimides are so poor in processability due to their high backbone rigidity that their applications are greatly limited. The introduction of long side chains not only enhances their processiblity but also makes useful contribution to discovering new application fields. In this article, a variety of novel aromatic polyimides with flexible side chains were prepared either from new dimines or new dianhydrides to measure the influence of the side chains on structure and properties of the polymers and their new applications as liquid crystal alignment layers, photosensitive polymers, alternating multilayer nano-films and photoluminescent materials are discussed.

• Journal of Korean Society for Quality Management
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• v.50 no.4
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• pp.679-700
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• 2022

Purpose: Smart lighting adjusts brightness and color temperature according to weather, the user's activity, mood, etc. This study performed user experience(UX) evaluation of smart lighting in a living lab. The purpose of evaluating UX and analyzing the evaluation results is to improve user-friendliness and market competitiveness of smart lighting Methods: A living lab is a virtual or physical space where various stakeholders participate to develop, verify, and evaluate products, services, or systems in a real-life environment. In this study, an environment of using smart lighting was established in the Smart Safety Living Lab. Subjects performed UX evaluation after interacting freely with smart lighting in the Smart Safety Living Lab. Results: As a result of UX evaluation, it was confirmed that UX was overall excellent and subjects were satisfied with setting a desired indoor mood through smart lighting. However, operating the switch of smart lighting may be difficult due to its complexity, and it is needed to improve some functionalities such as the brightness range provided by smart lighting. Conclusion: This study is expected to contribute to establishing the way of UX improvement of smart lighting. This study is also expected to contribute to developing smart lighting as a high-quality product by reflecting the subjects' needs and UX derived in a real-life environment.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.1033-1039
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• 1995

The magnetic system design of the KT-2 tokamak has been performed at KAERI. Design goal has been set to facilitate the so-called "advanced tokamak" studies, which is essential to secure the economy of the tokamak fusion reactors. Design features include a large-aspect-ratio machine configuration, long-pulse operation capability with heavy plasma shaping, hybrid magnetic field control and machine/in-vacuum structures for MHD stability.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1617-1621
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• 2012

The titanate nanotube (TNT) was hydrothermally synthesized in 10 M NaOH aqueous solution at $150^{\circ}C$ for 72 h. Titanate nanotube with high surface area (292 $m^2$/g) is a good candidate as a support for catalytic reaction or organic synthesis. Palladium nanoparticles with an average size of $ca$. 3 nm were well dispersed onto the surface of TNT nanotubes. Palladium loaded catalyst with high surface area shows a highly efficient ${\alpha}$ alkylation of ketones with primary alcohols.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2252-2254
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• 1997

There are increasing demands on high accruacy DC power supplies for varous basic science reseach, such as accelerators and plasma applications, in Korea. In this paper, we present a study on 1kW class DC power supply using the parell operation method of the flyback converters. This DC power supply is equipped with a remote controller for computer interface. A Serial Communication Controller(SCC) is also developed for large scale scientific facilities which is capable of handling upto 32 power supplies simultaneously with one serial port in the host computer.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.2
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• pp.67-75
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• 2000

virtual computer numerical control(VCNC) arises from the concept that one can experience pseudo-real machining with a computer-numerically-controlled(CNC) machine before actually cutting an object. To achieve accurate VCNC, it is important to determine abnormal behavior, such as chatter, before cutting. Detecting chatter requires an understanding of the dynamic cutting force model. In general, the cutting process is a closed loop system the consists of structural and cutting dynamic. Machining instability, namely chatter, results from the interaction between these two dynamics. Several previous reports have predicted stability for a single path, using a simple cutting force model without run out and penetration effects. This study considers both tool run out and penetration effects, using experimental modal analysis, to obtain predictions that are more accurate. The machining stability during a corner cut, which is a typical transient cut, was assessed from an evaluation of the cutting configurations at the corner.

• Macromolecular Research
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• v.16 no.6
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• pp.544-548
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• 2008

An HPLC column with a self-contained temperature control device was constructed for preparative temperature programmed interaction chromatography. Two Peltier plates were attached to a large bore column ($120{\times}22\;mm$ i.d.) and the column temperature was controlled by PID mode feed back control. At a flow rate of 1.5 mL/min, the column temperature could be increased and decreased at a rate as high as $50^{\circ}C/min$ and $10^{\circ}C/min$, respectively, which is much faster than using a column jacket and bath/circulator. The rapid heating and cooling rates allows a high repetition rate of chromatographic fractionation. The performance of the temperature controllable column was demonstrated successfully by the fractionation of homo-polymer precursors from diblock copolymers.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.145-150
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• 2013

As a recent global trend, the majority of mega-size plant projects are delivered through EPC (Engineering, Procurement and Construction) contracts, where a single contract is awarded for engineering, procurement, and construction. Under this contracting mechanism, it is challenging for contractors to carry out the projects under traditional project management processes used in design-bid-build projects. A new EPC Plant, the POSCO Special Steel Plant in Changwon, was built successfully at the beginning of 2012 and it is currently in full-scale production. The project has encountered a number of major difficulties however, with some technical and managerial issues through its development process. As summarized in this paper, the authors (as project participants with the contractor) investigated it as a post construction analysis and recorded the Lessons-learned for future project management improvement.

• Economic and Environmental Geology
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• v.53 no.5
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• pp.585-596
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• 2020

The 2017 Pohang Earthquakes occurred near a drill site in the Pohang Enhanced Geothermal System. Water injected for well stimulation was believed to have reactivated the buried near-critically stressed Miocene faults by the accumulation of the Quaternary tectonic strain. However, surface expressions of the Quaternary tectonic activity had not been reported near the epicenter of the earthquakes before the site construction. Unusual, large-scale water-escaped structures were identified 4 km away from the epicenter during a post-seismic investigation. The water-escaped structures comprise Miocene mudstones injected into overlying Pleistocene coastal sediments that formed during Marine Isotope Stage 5. This indicates the vulnerable state of the mudstones long after deposition, resulted from the combined effects of rapid tectonic uplift (before significant diagenesis) and the development of an aquifer at their unconformable interface of the mudstone. Based on the detailed field analysis and consideration of all possible endogenic triggers, we interpreted the structures to have been formed by elevated pore pressures in the mudstones (thixotropy), triggered by cyclic ground motion during the earthquakes. This interpretation is strengthened by the presence of faults 400 m from the study area, which cut unconsolidated coastal sediment deposited after Marine Isotope Stage 5. Geological context, including high rates of tectonic uplift in SE Korea, paleo-seismological research on Quaternary faults near the study area, and historical records of paleoearthquakes in SE Korea, also support the interpretation. Thus, epicenter and surrounding areas of the 2017 Pohang Earthquake are considered as a paleoseismologically active area, and the causative fault of the 2017 Pohang Earthquakes was expected to be nearly critical state.

• Corrosion Science and Technology
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• v.4 no.6
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• pp.236-241
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• 2005

Hydrogen induced cracking (HIC) is one of the hydrogen degradation phenomena of linepipe steels caused by $H_2S$ gas in the crude oil or natural gas. However, NACE TM0284-96 standard HIC test method is hard to satisfy the steel requirements for sour service application since it uses more severe environmental conditions than actual conditions. Therefore, in order to use steels effectively, it is required to evaluate HIC resistance of steels in the practical range of environmental severity. In this study, HIC resistance of two high strength low alloy (HSLA) steels being used as line pipe steels was evaluated in various test solutions with different $H_2S$ pressures and pH values. The results showed that the key parameter affecting crack area ratio (CAR) is $H_2S$ partial pressure of test solution when the pH value of test solution is not over 4. Hydrogen diffusivity was not a constant value, but it was rather affected by the hydrogen ion concentration (pH value) in the solution.