• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.803-810
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• 2007

An analytical method capable of predicting various stress-strain responses in axially loaded concrete confined with FRP (fiber reinforced polymers) composites in a rational manner is presented. Its underlying idea is that the volumetric expansion due to progressive microcracking in mechanically loaded concrete is an important measure of the extent of damage in the material microstructure, and can be utilized to estimate the load-carrying capacity of concrete by considering the corresponding accumulated damage. Following from this, an elastic modulus expressed as a function of area strain and concrete porosity, the energy-balance equation relating the dilating concrete to the confining device interactively, the varying confining pressure, and an incremental calculation algorithm are included in the solution procedure. The proposed method enables the evaluation of lateral strains consecutively according to the related mechanical model and the energy-balance equation, rather than using an empirically derived equation for Poisson's ratio or dilation rate as in other analytical methods. Several existing analytical methods that can predict the overall response were also examined and discussed, particularly focusing on the way of considering the volumetric expansion. The results predicted by the proposed and Samaan's bilinear equation models correlated with observed results with a reasonable degree, however it can be judged that the latter is not capable of predicting the response of lateral strains correctly due to incorporating the initial Poisson's ratio and the final converged dilation rate only. Further, the proposed method seems to have greater benefits in other applications by the use of the fundamental principles of mechanics.

• Journal of The Korean Astronomical Society
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• v.49 no.6
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• pp.295-306
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• 2016

We present the results of BV time-series photometry of the globular cluster NGC 288. Observations were carried out to search for variable stars using the Korea Microlensing Telescope Network (KMTNet) 1.6-m telescopes and a 4k pre-science CCD camera during a test observation from August to December, 2014. We found a new SX Phe star and confirmed twelve previously known variable stars in NGC 288. For the semi-regular variable star V1, we newly determined a period of 37.3 days from light curves spanning 137 days. The light-curve solution of the eclipsing binary V10 indicates that the system is probably a detached system. The pulsation properties of nine SX Phe stars were examined by applying multiple frequency analysis to their light curves. We derived a new Period-Luminosity (P-L) relation, ${\langle}M_V{\rangle}=-2.476({\pm}0.300){\log}P-0.354({\pm}0.385)$, from six SX Phe stars showing the fundamental mode. Additionally, the period ratios of three SX Phe stars that probably have a double-radial mode were investigated; $P_{FO}/P_F=0.779$ for V5, $P_{TO}/P_{FO}=0.685$ for V9, $P_{SO}/P_{FO}=0.811$ for V11. This paper is the first contribution in a series assessing the detections and properties of variable stars in six southern globular clusters with the KMTNet system.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.8 no.2
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• pp.107-117
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• 2013

The main objective of this study lies at examining economic features of IT security investment and comparing alternative mechanisms to achieve optimal provision of IT security resources within a firm. There exists a paucity of economic analysis that provide useful guidelines for making critical decisions regarding the optimal level of provision of IT security and how to share the costs among different users within a firm. As a preliminary study, this study first argues that IT security resources share some unique characteristics of pure public goods, namely nonrivalry of consumption and nonexcludability of benefit. IT security provision problem also suffers from information asymmetry problem with regard to the valuation of an individual user for IT security goods. Then, through an analytical framework, it is shown that the efficient provision condition at the overall firm level is not necessarily satisfied by individual utility maximizing behavior. That is, an individual provision results in a suboptimal solution, especially an underprovision of the IT security good. This problem is mainly due to the nonexcludability property of pure public goods, and is also known as a free-riding problem. The fundamental problem of collective decision-making is to design mechanisms that both induce the revelation of the true information and choose an 'optimal' level of the IT security good within this framework of information asymmetry. This study examines and compares three alternative demand-revealing mechanisms within the IT security resource provision context, namely the Clarke-Groves mechanism, the expected utility maximizing mechanism and the Groves-Ledyard mechanism. The main features of each mechanism are discussed along with its strengths, weaknesses, and different applicability in practice. Finally, the limitations of the study and future research are discussed.

• Development and Reproduction
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• v.15 no.4
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• pp.385-391
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• 2011

Human in vitro fertilization and embryo transfer (IVF-ET) program is a general procedure for infertile couples since first successful delivery on 1978 in UK and Korean first on 1985. Recently in Korea, more than 42,000 cases per year of IVF-ET were performed and showed good pregnancy rates compared worldwide data. The human IVF-ET procedure use many consumables, such as ovum pick-up (OPU) needles, centrifuge tubes, culture dish, ICSI pipette, culture media and ET catheters. Major of these materials are supported by the global companies. Thus, Korean IVF-ET program might be placed unstable situation by global economical risks. These uncertain problems could be overcome by the domestic production of IVF-ET materials and consumables. Two times questionnaires for Korean clinicians and researchers about the domestic production were performed and analyzed. Many of them requested domestic OPU needles, ET catheters, culture media and ICSI pipettes under good quality control and quality assurance system. This trial may be contributed to industrialization and to global competence of Korean IVF-ET program. The results of this survey can be provide a fundamental base for development and production of domestic materials and consumables for human IVF-ET program.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.1
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• pp.69-75
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• 2013

This study is a fundamental research to test the applicability of powdered MSWI(Municipal Solid Waste Incinerator) ash melted slag as a seed Crystal for crystallization reaction. Powdered ash melted slag was melted at $1100^{\circ}C$ and ground to lesser than 0.35mm. According to the result of the tests, calcium, enough for crystallization reaction, was eluted from powdered ash melted slag. Moreover, sample(Phosphorus concentration is under 10 mg/L), more than 90% of Phosphorus can be removed. So we rectify the Phosphorus concentration to 100 mg/L. Alkalinity, being well known that it interferes crystallization reaction, effect was studied for synthetic solution(100 mg/L initial Phosphorus concentration, 50 mg/L calcium, pH 8, 1% powdered ash melted slag dosage). For this result, we know that Phosphorus removal is hindered by alkalinity. In addition, the effect of reaction temperature was performed at the same method. The reaction velocity was increased through raising the reaction temperature.

• The Journal of the Korea Contents Association
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• v.13 no.10
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• pp.103-112
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• 2013

This study is the subsequent full-scale research to explore an undisputed top Korean TV drama writer, Su-Hyeon Kim, more profoundly, who has been out of scholarly pursuits. As it begins with discussing her mixed tendency by genre, we discuss about a useful reading method of the writer's relatively conservative genre, a home-drama. For the purpose of the study, it sets up the intertextuality theory. This study assents to that criticism of diminishing in its original meaning of M. Bakhtin's dialogism, which led J. Kristeva to name and fix the term. Therefore this paper mainly applies the Bakhtin's intertextuality theory to analyze common elements of the writer's and . Also it applies the G. Gennette's intertextuality of 'imprints' and 'transformation' between hypotext and hypertext to figure out their correlation. The analysis shows that the writer's home-drama realizes its mutual relationship and intersubjectivity of the Bakhtin's core intertextuality concept, which results in gaining viewers' popularity. And it also explains that the writer uses 'repetition' and 'transformation' method of intertextuality to contain its intended message in her own home-dramas. As the result of the study, to the writer, Su-Hyeon Kim, while a melodrama genre is for her fundamental inquiry of a 'privative', 'fractured' human being, a home-drama genre is for her message of the only solution of a 'family' to that inquiry with her own intention.

• Archives of Plastic Surgery
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• v.38 no.6
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• pp.798-802
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• 2011

Purpose: A wart is caused by epidermal infection with the human papilloma virus. Although wart naturally disappears in some cases, it require treatment because of pain, aesthetic problem, and the possibility of malignant change. Conventional non-surgical treatment cannot be a fundamental solution for the pain and has such disadvantages as frequent recurrence and difficulties in achieving a satisfactory outcome. A surgical procedure was performed on patients with wart and the procedure had a good outcome. Methods: We investigated the gender, age, lesion site, mean treatment duration, and presence or absence of recurrence in 21 patients with a wart within the period of January 2007 to July 2011. For local lesions, primary closure, including subcuticular suture after the excision, was performed. If the defect size was too big to do primary closure, we performed rotation flap. For wide multiple lesions, a split thickness skin graft was performed. Results: Among the 21 patients, 12 patients were male and 9 patients were female, and their mean age was 42 years (SD=17.38, range: 11~75 years). The lesion site was the foot in 10 patients, the hand in 8 patients, the face in 2 patients, and the scalp in 1 patient. The mean treatment duration was 13.5 days (SD=4.36, range: 6~15 days) for the primary closure or rotation flap, and 18.5 days (SD=2.12, range: 17~20 days) for the skin graft. 20 patients were cured without recurrence. No recurrence was observed in the patients who underwent primary closure or rotation flap. One of the two patients who underwent a skin graft of their wart that had covered their entire palm had local recurrence in part of her finger tips. Conclusion: We performed surgical procedure on recalcitrant wart. As a results, we can treat it with short treatment duration, low recurrence rate and less scarring and get high patient satisfaction.

• The Journal of the Korea Contents Association
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• v.13 no.12
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• pp.484-493
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• 2013

The Korean Government has provided public rental housing to stabilize civilian dwelling. However, unreliable management of public rental housing threatens the stability of residency. This study analyzes the default of public rental housing and the cause of default through a case study, which was intended for the residents in apartment complexes in danger of default. It also suggests countermeasures to cope with the problem of public rental housing. The results are listed as follows. First, rental housing apartments contribute a lot to the housing stability policy. On the other hand, the default of housing development, which is derived from the bankruptcy of housing management companies and the negligent control of government, brings about a serious problem for housing stability. Second, although the government has made a steady effort to solve this default problem, 9000 residents from 8 apartment complexes in Korea have experienced extreme unstable residency. Third, there are many causes for the default of public rental housing such as unqualified management companies and cursory monitoring by the government. The fundamental solution is to prevent public rental housing management companies from managing, or to build a new management system of public rental housing. To solve this problem, it's recommendable to delete the application term in the special law on the default of public rental housing so that it can be applied to all default apartments. If it is not possible to perform the policy for financial reasons, a new supply of civil housing provided by private companies needs to be re-examined completely or banned.

• Journal of Powder Materials
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• v.13 no.5 s.58
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• pp.327-335
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• 2006

In the development of new hydrogen absorbing materials for a next generation of metal hydride electrodes for rechargeable batteries, metastable Mg-Ni-based compounds find currently special attention. Amor phous-nanocrystalline $Mg_{63}Ni_{30}Y_7$ and $Mg_{50}Ni_{30}Y_{20}$ alloys were produced by mechanical alloying and melt-spinning and characterized by means of XRD, TEM and DSC. On basis of mechanically alloyed Mg-Ni-Y powders, complex hydride electrodes were fabricated and their electrochemical behaviour in 6M KOH (pH=14,8) was investigated. The electrodes made from $Mg_{63}Ni_{30}Y_7$ powders, which were prepared under use of a SPEX shaker mill, with a major fraction of nanocrystalline phase reveal a higher electrochemical activity far hydrogen reduction and a higher maximum discharge capacity (247 mAh/g) than the electrodes from alloy powder with predominantly amorphous microstructure (216 mAh/g) obtained when using a Retsch planetary ball mill at low temperatures. Those discharge capacities are higher that those fur nanocrystalline $Mg_2Ni$ electrodes. However, the cyclic stability of those alloy powder electrodes was low. Therefore, fundamental stability studies were performed on $Mg_{63}Ni_{30}Y_7$ and $Mg_{50}Ni_{30}Y_{20}$ ribbon samples in the as-quenched state and after cathodic hydrogen charging by means of anodic and cathodic polarisation measurements. Gradual oxidation and dissolution of nickel governs the anodic behaviour before a passive state is attained. A stabilizing effect of higher fractions of yttrium in the alloy on the passivation was detected. During the cathodic hydrogen charging process the alloys exhibit a change in the surface state chemistry, i.e. an enrichment of nickel-species, causing preferential oxidation and dissolution during subsequent anodization. The effect of chemical pre-treatments in 1% HF and in $10\;mg/l\;YCl_3/1%\;H_2O_2$ solution on the surface degradation processes was investigated. A HF treatment can improve their anodic passivation behavior by inhibiting a preferential nickel oxidation-dissolution at low polarisation, whereas a $YCl_3/H_2O_2$ treatment has the opposite effect. Both pre-treatment methods lead to an enhancement of cathodically induced surface degradation processes.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.4
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• pp.301-317
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• 2002

Recently, a geophysical exploration technology is frequently utilized in the civil engineering field as well as in the resource exploration. It might be important for civil engineers to understand the fundamental theory of seismic survey and limitation of the technique when utilizing these techniques in the civil engineering field. A 3-dimensional migration technique based on the principle of ellipsoid to predict the fractured zone ahead of tunnel face utilizing the tunnel seismic survey was proposed so that the geometry of the fractured zone can be estimated, i.e. the angle between tunnel axis and discontinuity zone, and the dip. Moreover, a numerical analysis technique to simulate the TSP (Tunnel Seismic Prediction) test was proposed in this paper. Based on parametric studies, the best element size, the analysis time step, and the dynamic characteristics of pressure source were suggested to guarantee the stability and accuracy of numerical solution. Example problems on a hypothetical site showed the possibility that the 3-dimensional migration technique proposed in this paper appropriately estimate the 3D-geometry of fractures ahead of tunnel face.