• The Journal of Korean Institute for Practical Engineering Education
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• v.1 no.1
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• pp.61-65
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• 2009

Due to the less variety of experiment equipments for engineering education, the development of designated educational equipment is really in urgent need at most time. Especially for the in-depth engineering major subject, vibration engineering, there are almost no related educational equipments in Korea. Accordingly, in order to simulate the vibration phenomena occurred in the actual field, the development of educational equipment for vibration engineering theory and experiment education is required. This paper introduces four development educational equipments developed in graduated research works, which are critical speed test educational equipment, balancing machine educational equipment, isolation educational equipment using eddy current and active vibration isolation educational equipment. Through using them in experiment lesson, the utilization and practicality of educational equipment are verified. The proposed improvement for future development and application of educational equipment is shown in addition.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.4
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• pp.253-260
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• 1999

In this paper, the impedance characteristic of wire-plate pulsed plasma reactor was investigated by experiment. The experiment have carried out under the several conditions of voltage, wire length and wire-plate distance. The impedance of reactor wad decreased with increasing voltage and wire length. The nature of discharge in reactor was changed from streamer corona to spark with increasing incident energy, from which we understood the critical energy density between the two discharges. Fromthis experiment, we proposed the method for the impedance matching between pulse generator and pulsed plasma reactor. Additionally, we succeeded in the analysis ofstray inductance of 0.5MW reactor using EMTP (ElectroMagnetic Transients Program). This means that EMTP is also useful for the analysis of inevitable stray inductance of forthcoming a large scale reactor.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.348-354
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• 1996

This study was carried out to investigate factors influencing on the groundwater quality at controlled horticulture in Honam area in 1995. The deeper groundwater sampling, the lower concentrations of $NH_4-N$ and $NO_3-N$ were observed. There was no difference in concentrations of $SO_4\;^{2-}$ and $Na^+$ in the groundwater below 15m. Contents of $NH_4-N$, $NO_3-N$ and $PO_4\;^{3-}$ in groundwater were the highest at rice transplanting season(the late May) and that of $SO_4\;^{2-}$, $Na^+$ and $Cl^-$ were the highest at dry season(the mid-February). Continuous cultivation of horticultural crops showed higher concentration of $NH_4-N$, $NO_3-N$, $PO_4\;^{3-}$, $Na^+$ and $Cl^-$ in groundwater than rotational culture with rice. The longer cultivation years with horticultural crops, the higher concentrations of $NO_3-N$, $PO_4\;^{3-}$, $SO_4\;^{2-}$ and $Cl^-$ were shown, and constitutional ratio of $NO_3-N$ among the anions increased gradually. Nitrate-N level, exceeded 20mg/l, the critical level for agricultural usage, frequently at Yongjinmyeon Wanju and Janglockdong Kwangju, and $PO_4\;^{3-}$ levels were higher at Seogtandong Iksan than the other places.

• Research in Mathematical Education
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• v.15 no.1
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• pp.31-44
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• 2011

An impetus for reviving research in mathematical problem solving is the recent advance in methodological thinking, namely, the design experiment ([Gorard, S. (2004). Combining methods in educational research. Maidenhead, England: Open University Press.]; [Schoenfeld, A. H. (2009). Bridging the cultures of educational research and design. Educational Designer. 1(2). http://www.educationaldesigner.orgied/volume1/issue21]). This methodological approach supports a "re-design" of contextual elements to fulfil the overarching objective of making mathematical problem solving available to all students of mathematics. In problem solving, components critical to successful design in one setting that may be adapted to suit another setting include curriculum design, assessment strategy, teacher capacity, and instructional resources. In this paper, we describe the implementation, over three years, of a problem solving module into the main mathematics curriculum of an Integrated Programme school in Singapore which had sufficient autonomy to tailor-fit curriculum to their students.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.91-96
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• 2014

This research deals with the combustion experiment of pine trees, which are the most representative species in Korea. Experimental data are compared with theoretical ones using Fire Simulation Program(FDS). It is considered that horizontal/vertical temperature distribution and radiant heat influence on adjacent areas in fire scenes. The linear function for separation distance to temperature was drawn by applying Stefan-Boltzmann's law; $y=112.13133{\times}({\sigma}T^4)^{-0.52916}$ for calculating the separation distance. In combustion experiment, the radiant heat came to $1.4{\sim}1.5kW/m^2$ in case of the separation distance by one meter. The numerical values mean that human body show the critical level of pain after one minute without a protective equipment.

• Corrosion Science and Technology
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• v.21 no.2
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• pp.158-169
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• 2022

The objective of this study was to investigate the electrochemical behavior and damage degree of metal surface under different conditions by performing a potentiodynamic polarization experiment using an electropolishing solution for UNS S31603 based on initial delay time and surface roughness (parameters). A second anodic peak occurred at initial delay time of 0s and 100s. However, it was not discovered at 1000s and 3600s. This research referred to an increase in current density due to hydrogen oxidation reaction among various hypotheses for the second anodic peak. After the experiment, both critical current density and corrosion current density decreased when the initial delay time (immersion time) was longer. As a result of surface analysis, characteristics of the potentiodynamic polarization behavior were similar with roughness, although the degree of damage was clearly different. With an increase in surface roughness value, the degree of surface damage was precisely observed. As such, electrochemical properties were different according to the immersion time in the electropolishing solution. To select electropolishing conditions such as applied current density, voltage, and immersion time, 1000s for initial delay time on the potentiodynamic polarization behavior was the most appropriate in this experiment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.12
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• pp.1747-1752
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• 2012

This study investigated the physiochemical characteristics of Xanthoceras sorbifolia seed oil. Xanthoceras sorbifolia seed oil was extracted by supercritical fluid extraction (420 atm, $50^{\circ}C$), hexane extraction and heat-pressed extraction ($160^{\circ}C$, $180^{\circ}C$). Acid values and peroxide values were evaluated, as well as the degree of lipid oxidation. The heat-pressed ($160^{\circ}C$) extraction gave a $53.5{\pm}2.5%$ higher yield of oil, compared with the other extraction methods. The acid values from the super critical fluid extraction were the highest, while peroxide values were highest from the heat-pressed extraction at $160^{\circ}C$ (3.10 meq/kg). The contents of linolenic acid and oleic acid were 38.63~41.13% and 26.29~26.85%, respectively. Contents of stigmasterol and ${\beta}$-sitosterol were 6.01~6.49 mg/100 g and 58.19~59.85 mg/100 g, respectively. These results indicate that Xanthoceras sorbifolia seed oil can possibly serve as new edible oils.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.117-117
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• 2002

The oocytes from most of animal species accumulate genetic information and other necessary materials during oogenesis for the later use in the early development. Over the years oocyte maturation has been studied extensively both in vitro and in vivo. Particularly, maturation of follicular oocyte in vitro becomes one of the important tools for the studies of basic cell biology, the in vitro technology of animal production, and in particular, the somatic cell cloning by nuclear transfer. We examined meiotic maturation and cumulus expansion in the presence of translation or transcription inhibitors for varying periods of in viかo maturation (IVM) of pig oocyte. In Experiment 1, the results revealed that translation and transcription inhibitors inhibited cumulus expansion and meiotic maturation during 35h of IVM. However, 50 to 60% of the oocytes underwent nuclear maturation without cumulus expansion during 75h of IVM. The rest of the oocytes were arrested at metaphase I (40-50%) in the presence of the inhibitors. In Experiment II, the OCCs were exposed to the drugs only for 15h to examine translation and transcription inhibitors on cumulus expansion and meiotic maturation. Transcription inhibitors for 15h did not arrest meiotic maturation when the oocytes were cultured for subsequent, necessary period of IVM, whereas cumulus expansion was completely inhibited, suggesting that initial 15h is critical transcription activity far cumulus expansion. Translation inhibitors for 15h exposure did not alter cumulus expansion and meiotic maturation during subsequent culture in the absence of the drugs. In Experiment III, the OCCs were exposed to the drugs only for later 30h to examine the influence of transcription and translation inhibitors on oocyte maturation. Interestingly, all meiotic maturation underwent normally with full expansion of cumulus. Similar results were obtained from Experiment IV where 5h of exposure from 15 to 20h of IVM culture to the drugs was performed and subsequently cultured for same period in fresh medium. Taken there results together, both transcription and translation are necessary for nuclear maturation and cumulus expansion, and first 15h IVM for cumulus expansion is critical. The arrested oocytes by the drugs were still capable of undergoing nuclear maturation, although cumulus expansion was affected.

• Phonetics and Speech Sciences
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• v.2 no.3
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• pp.115-124
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• 2010

The current study investigated the role of acoustic correlates of domain-initial strengthening in lexical segmentation of a non-native language. In a series of cross-modal identity-priming experiments, native Korean listeners heard English auditory stimuli and made lexical decision to visual targets (i.e., written words). The auditory stimuli contained critical two word sequences which created temporal lexical ambiguity (e.g., 'mill#company', with the competitor 'milk'). There was either an IP boundary or a word boundary between the two words in the critical sequences. The initial CV of the second word (e.g., [$k_{\Lambda}$] in 'company') was spliced from another token of the sequence in IP- or Wd-initial positions. The prime words were postboundary words (e.g., company) in Experiment 1, and preboundary words (e.g., mill) in Experiment 2. In both experiments, Korean listeners showed priming effects only in IP contexts, indicating that they can make use of IP boundary cues of English in lexical segmentation of English. The acoustic correlates of domain-initial strengthening were also exploited by Korean listeners, but significant effects were found only for the segmentation of postboundary words. The results therefore indicate that L2 listeners can make use of prosodically driven phonetic detail in lexical segmentation of L2, as long as the direction of those cues are similar in their L1 and L2. The exact use of the cues by Korean listeners was, however, different from that found with native English listeners in Cho, McQueen, and Cox (2007). The differential use of the prosodically driven phonetic cues by the native and non-native listeners are thus discussed.

• Journal of Biomedical Engineering Research
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• v.31 no.3
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• pp.187-193
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• 2010

In this study we have designed and fabricated an inexpensive micro electronic system that we call Alvitek. It can indirectly but accurately predict and display the partial pressures of alveolar oxygen and carbon dioxide for the patients in the ICU of a hospital. Alvitek consists of both hardware part and software part. Performance of the system is tested by animal experiment with pigs for various $F_{t}e_{2}$ and RR(Respiratory Rate) values under the mechanical ventilation. The predicted alveolar gas partial pressures are cprpared with the approximate alveolar oxygen partial pressures easily calculated by the physician’s bedside formula. As a result, we have concluded that the relative error of A-$aDe_2$ calculated by the bedside formula grows seriously for lower $F_{t}e_{2}$ values. The present prediction method of Alvitek is henceforth believed very meaningful to the physicians. The system hardware and software are described in the text.