• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.248-250
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• 2003

Thermal analysis is performed to protect the propulsion system of low-earth-orbit earth observation satellite from unwanted thermal disaster like propellant freezing. To implement thermal design adequately, heater powers for the propulsion system estimated through the thermal analysis are decided. Based on those values anticipated herein, the average power for propulsion system becomes 22.02 watts when the only one redundant catalyst bed heater is turned on. When for the preparation of thruster firing, 25.93 watts of the average power is required. All heaters selected for propulsion components operate to prevent propellant freezing meeting the thermal requirements for the propulsion system with the worst-case average voltage, i.e. 25 volts.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.645-650
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• 1997

An oxide fuel small size core (1200 MWt) was analyzed in comparison with a large size core (3600 MWt) in order to evaluate the size effects on transient safety performances of liquid-metal reactors (LMRs). in the first part of the study, main static safety parameters (i.e., Doppler coefficient, sodium void effect, etc.) of the two cores were characterized, and the second part of the study was focused on the dynamic behavior of the cores in two representative transient events: the unprotected loss-of-flow(ULOF) and the unprotected transient overpower (UTOP). Margins to fuel molting and sodium boiling have been evaluated for these representative transients. Results show that the small core has a generally better or equivalent level of safety performances during these events.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.276-280
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• 1999

The different core-modified porphyrins 21-thia-23-carba-12-aza-5,10-dimesityl-15,20-diphenylporphyrin (6), and their N(12)-methyl derivatives (8) were synthesized by acid-catalyzed [3+1] condensation of the corresponding 16-thia-5,10-dimesityltripyrromethanes and 2,4-bis[(α-hydroxy-α-phenyl)methyl]pyrrole. Spectroscopic evidence indicates the existence of two different tautomeric forms at room temperature in porphyrin (6). A third form of tautomer was observed when the temperature was lowered to 223 K. The most stable tautomer is one in which the nitrogenic proton resides outside the core of the macrocycle. The ratio of the three different tautomers (outer N-H/ two inner N-H, i.e. 6/12/13) was 1/l/0.5 in the case of (6) while the ratio of 1/l/0.3 was observed in the case of (10). In the case of 21-oxa-23-carba-12-aza-5,10,15,20-tetraphenylporphyrin (7), the only stable tautomeric form observed by 1H NMR was the one that nitrogenic proton resides inside the core on

• Macromolecular Research
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• v.17 no.7
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• pp.499-505
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• 2009

General, fast, and efficient stitching methods are presented for the synthesis of Fr$\acute{e}$chet-type dendrimers with linear units at a core, as a preliminary investigation for the synthesis of dendritic-linear-dendritic materials. The synthetic strategy involved an inexpensive, 1,3-dipolar, cycloaddition reaction between an alkyne and an azide in the presence of the Cu(I) species, which is known as the best example of click chemistry. The linear core building blocks, 1,7-octadiyne and 1,6-diazidohexane, were chosen to serve as the alkyne and azide functionalities for dendrimer growth via click reactions with the azide and alkyne-dendrons, respectively. These two building blocks were employed together with the azide- and alkyne-functionalized Fr$\acute{e}$chet-type dendrons in a convergent strategy to synthesize two kinds of Fr$\acute{e}$chet-type dendrimers with different linear core units. This comparative efficiency of the click methodology supports the fast and efficient synthesis of dendritic-linear-dendritic materials with the tailor made core unit.

• The Journal of Korean Philosophical History
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• no.23
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• pp.7-65
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• 2008

The object of this essay is to apply the Leadership Theory, current interest in Asian Philosophy, to Korean appliance. This is to associate contemporary Leadership Theory with Chosun Confucianism in order to discover the Korean Leadership Prototype, and seek the possibility of applying it for modern usage. The essay uses two analysis models. The tools used for the methodology consists of the personal characteristics of the leader as one axis and ruling out the roles in order to develop the discussion as the other axis. First axis is the process of the leader setting the identity and strengthening the ability to successfully deploy his/her leadership. The second axis is comprised of four specific fields where the leadership is deployed. The four sectors are Self Sector, Relationship Sector, Team Sector and Community Sector. Core values of each sector have been set up and specific competences have been presented. In the Self Sector, $zh{\grave{i}}x{\bar{i}}n$(治心) and $ch{\acute{i}}j{\grave{i}}ng$(持敬) have been set as core values and $l{\grave{i}}zh{\grave{i}}$(立志) and $sh{\acute{i}}x{\bar{i}}n$(實心) as their competences. In the Relationship Sector and Team Sector, circumstances(時宜) and $sh{\acute{i}}sh{\grave{i}}g{\bar{e}}ngzh{\bar{a}}ng$(實事更張) were set as core values, accordingly. Lastly for the Community sector, the core value, 'Ideal Leader and the Visions of and Ideal Community', was conceptualized as '$m{\grave{ui}}m{\acute{i}}nzh{\grave{i}}zh{\grave{i}}$(牧民至治)'. The leadership is then expanded from the Self Sector to the final stage through its processes. Through this research, it can be found out that the Korean Leadership Model is not rigid to just cover a specific point in time or situation, but embraces many contemporary leadership concepts, thus having the characteristics of a comprehensive leadership theory.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.29-35
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• 2012

The treatments for spinal canal stenosis are radicular cyst removal, spine fusion, and implantation of an artificial intervertebral disc. Artificial intervertebral discs have been most widely used since the mid-2000s. The study of artificial intervertebral discs has been focused on the analysis of the axial rotation, lateral bending, the degrees of freedom of the disc, and flexion-extension of the vertebral body. The issue of fatigue failure years after the surgery has arisen as a new problem. Hence, study of artificial intervertebral discs must be focused on the fatigue failure properties and increased durability of the sliding core. A finite element model based on an in the artificial intervertebral disc (SB Charit$\acute{e}$ III) was produced, and the influence of the radius of curvature and the change in the coefficient of friction of the sliding core on the von-Mises stress and contact pressure was evaluated. Based on the results, new artificial intervertebral disc models (Models-I, -II, and -III) were proposed, and the fatigue failure behavior of the sliding core after a certain period of time was compared with the results for SB Charit$\acute{e}$ III.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.28-32
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• 2010

Technical demands for aspheric glass lens formed in market increases its application from simple camera lens module to fiber optics connection module in optical engineering. WC is often used as a metal core of the aspheric glass lens, but the long life time is issued because it fabricated in high temperature and high pressure environment. High hard thin film coating of lens core increases the core life time critically. Diamond Like Carbon(DLC) thin film coating shows very high hardness and low surface roughness, i.e. low friction between a glass lens and a metal core, and thus draw interests from an optical manufacturing industry. In addition, DLC thin film coating can removed by etching process and deposit the film again, which makes the core renewable. In this study, DLC films were deposited on the SiC ceramic core. The process variable in FVA(Filtered Vacuum Arc) method was the substrate bias-voltage. Deposited thin film was evaluated by raman spectroscopy, AFM and nano indenter and measured its crystal structure, surface roughness, and hardness. After applying optimum thin film condition, the life time and crystal structure transition of DLC thin film was monitored.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.361-365
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• 2003

A unipolar-type E-chuck was fabricated for the application of holding silicon wafers in the oxide etcher. For the fabrication of the unipolar ESC, core technologies such as coating of polyimide films and anodizing treatment of aluminum surface were developed. The polyimide films were prepared on thin coated copper substrates to minimize the plasma damage during the etch processing. Thin film heater technology was also developed for new type of E-chuck.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2107-2111
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• 2023

The aim of the study is the activity concentration measurements of organic and inorganic ¹⁴C in the discharges of JSC "Institute of Nuclear Materials" (INM). In INM the research water-water reactor "IVV-2M" is operating. Collecting of ¹⁴C species was performed using a ¹⁴C sampler with a chromium oxide and platinum catalysts at different temperatures: 400, 550 and 700 ℃. The measurements of ¹⁴C activity were performed using a liquid scintillation counter. The share of organic ¹⁴C in emissions ranged from 0.30 to 0.84 and depends on the temperature of the catalyst, core structure and reactor operating mode.

• Macromolecular Research
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• v.12 no.1
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• pp.11-21
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• 2004

Toughening of epoxy resins for improvement of crack resistance has been the subject of intense research interest during the last two decades. Epoxy resins are successfully toughened by blending with a suitable liquid rubber, which initially remains miscible with epoxy and undergoes a phase separation in the course of curing that leads to the formation of a two-phase microstructure, or by directly blending preformed rubbery particle. Unlike the situation for thermoplastics, physical blending is not successful for toughening epoxy resins. Recent advances in the development of various functionalized liquid rubber-based toughening agents and core-shell particles are discussed critically in this review.