• Journal of KIISE:Software and Applications
• /
• v.29 no.7
• /
• pp.450-464
• /
• 2002

Many modern complex systems, including most object-oriented systems, have dynamic characteristics that their components are dynamical]y configured during run-time. However, few analysis techniques are available that consider the dynamic nature of systems explicitly. We propose a specification and analysis method for these dynamic systems. We design a new temporal logic, called HDTL, to specify the properties of dynamically evolving systems, and tune up the tableau method for this logic. HDTL incorporates variables and quantifiers that enable the automatic analysis. Using HDTL and the analysis method, we can specify the correctness requirements of systems and check whether the system actually agree with the requirements or not. An experiment shows that HDTL is suitable for specifying dynamic properties and the analysis technique works well.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.225-228
• /
• 2009

Hot-firing tests were performed on the gas generator which is a technology development/demonstration model for a 75 ton-class liquid rocket engine. A heat-sink type combustion chamber was used for initial performance examination of the injector and mixing head. This paper explains not only preparation works for hot-firing tests but also the acquired results such as pressure, temperature distribution, and pressure fluctuation.

• Journal of Adhesion and Interface
• /
• v.4 no.3
• /
• pp.14-20
• /
• 2003

In order to study the radiation curing behavior of poly(ethylene glycol 400) dimethacrylate and ethylene glycol dimethacrylate, we investigated the influence of temperature and photoinitiator concentration by photo-DSC. As the number of ethylene glycol unit, the concentration of photoinitiator, and the reaction temperature increased, the reaction speed of PEG400DMA and EGDMA increased. Although the reaction speed of PEG400DMA was lower than EGDMA, the overall conversion of PEG400DMA was high.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.108-111
• /
• 2017

High performance upper stage engine is necessary for space launch vehicles of geostationary orbit, and staged combustion cycle engine is suitable due to high specific impulse. Technology demonstration model for 9 tonf class staged combustion cycle engine, which is consisted of turbopump, preburner, combustion chamber and supply system, was assembled, and hot-firing test was conducted for three seconds in Upper-stage Engine Test Facility of Naro Space Center. Ignition, combustion and shut down of engine system was performed normally, and its performance parameters were evaluated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.04a
• /
• pp.31-34
• /
• 2011

Design and fabrication of Technology Demonstration Model(TDM) of 75 tonf regenerative cooling thrust chamber were described. It has design chamber pressure of 60 bar, propellant mass flow rate of 243.6 kg/s, and nozzle expansion ratio of 12. It has a single welded structure of the mixing head and the chamber. Design and fabrication technologies established through this TDM can be used to development of flight model.

• Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
• /
• v.6
• /
• pp.241-261
• /
• 2002

In der Grammatik $f\"{u}r$ die Lernenden werden die deutschen Tempora nach dem lateinischen Vorbild dargestellt: $Pr\"{a}sens,\;Pr\"{a}teritum$, Perfekt, Plusquamperfekt, Futur I und Futur II. Und diese sechs Tempora werden in die drei Zeitstufen kIassifiziert: Gegenwart, Vergangenheit und Zukunft. Aber die Zeitformen $k\"{o}nnen$ nicht in direkter und geradliniger Weise auf bestimmte objektive Zeiten beziehen. Das $Verh\"{a}ltnis$ zwischen Zeitinhalt und Zeitform ist verwickelter und komplexer. Man denkt nach, wie viele Tempora es in der deutschen Sprache gibt und warum die Tempora Funktionen, die nicht nur Zeitinhalt, sondern auch andere Inhalte(z.B. modale) $ausdr\"{u}ken$, haben. Urn die Probleme zu $erl\"{a}utern$, sollen wir die deutschen Tempora von der lateinischen Tempuskategorie abtrennen und ein geeignetes Tempussystem $f\"{u}r$ die deutsche Sprache suchen. Dazu $m\"{u}ssen$ wir beobachten, Wie die deutschen Tempora konstruiert wurden. Im Lateinischen handelt es sich bei allen sechs Tempora um Verbformen, um bestimmte ($n\"{a}mlich$ die indikativischen) Formen des finiten Verbs. Im Deutschen aber finden wir unter den Tempora nur zwei richtige Verbformen $(Pr\"{a}sens\;und\;Pr\"{a}teriturn),\;die\;\"{u}brigen$ Tempora sind verbale Komplexe, drei zweiwortige (Perfekt, Plusquamperfekt, Futur I) und ein dreiwortiger (Futur II). Und das deutsche Tempussystem besteht aus den zwei Polen: Vergangenes und Nicht-Vergangenes oder $Temporalit\"{a}t\;und\;Atemporalit\"{a}t$. Die Tempusform $Pr\"{a}teritum\;geh\"{o}rt\;zu\;Temporalit\"{a}t$ und die Tempusform $Pr\"{a}sens\;zu\;Atemporalit\"{a}t$. Das $Pr\"{a}sens\;und\;das\;Pr\"{a}teritum$ sind die Grundtempora im Deutschen und die $\"{u}brigen$ Tempora sind die durch den Aspekt erweiterten und die zusammengesetzten Tempora. Sie haben deswegen die inneren Merkmale Aspekt und Modale $au{\ss}er$ Zeitbezug. Wir $k\"{o}nnen$ diese inneren Merkmale im Tempusgebrauch feststellen. Als Funktionen der Tempora der deutschen Sprache im Tempusgebrauch sind zu registrieren: Bezeichnung zeitlicher Gegebenheit, modale Implikationen, Aspektangaben und semantische Akzentuierungen. Und noch eins: Die Funktion des neutralen Referieren des Inhaltes durch das atemporale $Pr\"{a}sens$. Das $Pr\"{a}sens$ wird durch diese Referentfunktion zu dem Haupttempus auch in der geschriebenen Sprache. Trotzdem nennt man das $Pr\"{a}teritum$ in der geschriebenen Sprache das Haupttempus. Ist das $Pr\"{a}teritum$ dann in der Tat in der geschriebenen Sprache das Haupttempus? Genau genommen ist das $Pr\"{a}sens$ offenbar ein Haupttempus. Es wird nicht nur in der gesprochenen Sprache, sowohl auch in den geschriebenen nichtbelletristischen Texten $haupts\"{a}chlich$ benutzt. Aber nur die belletristischen Texte werden durch das $Pr\"{a}teritum$ beherrscht. Der Gebrauch des $Pr\"{a}teritums$ als Haupttempus $beschr\"{a}nkt$ sich nur auf die Belletristik. Wir glauben, die Untersuchung $\"{u}ber$ den Tempusgebrauch und die Tempusfunktion in den verschiedenen Textsorten sei besonders dem Nichtmuttersprachler wichtig, weil die Textsorten beim Tempusgebrauch eine Wahl des Tempus beeinflussen.

• Applied Chemistry for Engineering
• /
• v.24 no.5
• /
• pp.499-506
• /
• 2013

As the usuage of tempered glass for touch panel increased rapidly with the development of industry, the amount of UV curable coating solution used to protect glass surfaces during a tempered glass manufacturing process increased as well. The UV curable coating has advantages compared to thermal curing such as shortened curing time and non-solvent. Appropriated polymer and monomer were used as an acid polymer to grant an alkali peeling ability. The monomers were 2-hydroxyl methylacrylate, 1,6-hexanediol diacrylate and dipentaerythritol hexaacrylate which have acryl groups of 1, 2, and 6, respectively. The combination of three different types of photoinhibitors were used and bisphenol A epoxy diacrylate was used as an oligomer. In this study, experiments were carried out by controlling the amount of photoinitiator, oligomer, and additive while maintaining the constant content of the acid polymer and the acrylic monomer. The changes in physical properties according to the additive content were investigated. It was found that the combination of photoinitiators was necessary to achieve the hardness above 4H and it was possible to control the delamination type of the coating film from a sheet to pieces by the addition of TPO as an initiator. The increase in oligomer contents increased the hardness and adhesiveness alongside dissection time. Talc content of 20 wt% showed the best results.

• Restorative Dentistry and Endodontics
• /
• v.36 no.2
• /
• pp.108-113
• /
• 2011

Objectives: To determine the effect of the spectral output of single and dual-peak light emitting diode (LED) curing lights on the microhardness and color stability of commercial resin composites formulated with camphorquinone and alternative photoinitiators in combination. Materials and Methods: Three light-polymerized resin composites (Z100 (3M ESPE), Tetric Ceram (Ivoclar Vivadent) and Aelite LS Posterior (Bisco)) with different photoinitiator systems were used. The resin composites were packed into a Teflon mold (8 mm diameter and 2 mm thickness) on a cover glass. After packing the composites, they were light cured with single-peak and dual-peak LEDs. The Knoop microhardness (KHN) and color difference (${\Delta}E$) for 30 days were measured. The data was analyzed statistically using a student's t-test (p < 0.05). Results: All resin composites showed improved microhardness when a third-generation dual-peak LED light was used. The color stability was also higher for all resin composites with dual-peak LEDs. However, there was a significant difference only for Aelite LS Posterior. Conclusions: The dual-peak LEDs have a beneficial effect on the microhardness and color stability of resin composites formulated with a combination of camphorquinone and alternative photoinitiators.

• Journal of Space Technology and Applications
• /
• v.1 no.3
• /
• pp.319-336
• /
• 2021

This paper discusses the results of launch environment tests for the engineering qualification model (EQM) of nanosatellite Scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) for scientific missions and lessons learned for the design of nanosatellites. SNIPE is a group of four formation-flying 6U nanosatellites with a range of payloads for missions including space weather measurement. We developed the EQM to verify the preliminary design prior to fabricating the flight model. Launch environment test of EQM was conducted for the first time in 2019, and all failures were corrected and verified at the second test conducted in 2021. A notable point of the two tests is that the nanosatellite deployer used in the first test is different from that of the second test. The second deployer has the capability to fix the internal satellite whereas the first deployer just contains and deploys the satellite. Thus actual mechanical loads the satellite receives is reduced for the second test compared to the first test. This work compares the mechanical responses of two tests and proposes general guidelines for structural design of nanosatellites.

• Korea Petroleum Association Journal
• /
• no.2 s.168
• /
• pp.74-80
• /
• 1995