• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.81-94
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• 2010

This paper deals with the fracture simulation of UHPFRC girder with the interface type model. Based on the existing numerical simulation of quasi-brittle fracture in normal strength concrete, constitutive modeling for UHPFRC I-girder has been improved by including a tensile hardening at the failure surface. The finite element formulation is based on a triangular unit, constructed from constant strain triangles, with nodes along its sides and neither at the vertex nor the center of the unit. Fracture is simulated through a hardening/softening fracture constitutive law in tension, a softening fracture constitutive law in shear as well as in compression at the boundary nodes, with the material within the triangular unit remaining linear elastic. LCP is used to formulate the path-dependent hardening-softening behavior in non-holonomic rate form and a mathematical programming algorithm is employed to solve the LCP. The piece-wise linear inelastic yielding-failure/failure surface is modeled with two compressive caps, two Mohr-Coulomb failure surfaces, a tensile yielding surface and a tensile failure surface. The comparison between test results and numerical results indicates this method effectively simulates the deformation and failure of specimen.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.276-280
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• 2010

Copper(Cu) as an interconnecting metal layer can replace aluminum (Al) in IC fabrication since Cu has low electrical resistivity, showing high immunity to electromigration compared to Al. However, it is very difficult for copper to be patterned by the dry etching processes. The chemical mechanical polishing (CMP) process has been introduced and widely used as the mainstream patterning technique for Cu in the fabrication of deep submicron integrated circuits in light of its capability to reduce surface roughness. But this process leaves a large amount of residues on the wafer surface, which must be removed by the post-CMP cleaning processes. Copper corrosion is one of the critical issues for the copper metallization process. Thus, in order to understand the copper corrosion problems in post-CMP cleaning solutions and study the effects of DC biases and post-CMP cleaning solution concentrations on the Cu film, a constant voltage was supplied at various concentrations, and then the output currents were measured and recorded with time. Most of the cases, the current was steadily decreased (i.e. resistance was increased by the oxidation). In the lowest concentration case only, the current was steadily increased with the scarce fluctuations. The higher the constant supplied DC voltage values, the higher the initial output current and the saturated current values. However the time to be taken for it to be saturated was almost the same for all the DC supplied voltage values. It was indicated that the oxide formation was not dependent on the supplied voltage values and 1 V was more than enough to form the oxide. With applied voltages lower than 3 V combined with any concentration, the perforation through the oxide film rarely took place due to the insufficient driving force (voltage) and the copper oxidation ceased. However, with the voltage higher than 3 V, the copper ions were started to diffuse out through the oxide film and thus made pores to be formed on the oxide surface, causing the current to increase and a part of the exposed copper film inside the pores gets back to be oxidized and the rest of it was remained without any further oxidation, causing the current back to decrease a little bit. With increasing the applied DC bias value, the shorter time to be taken for copper ions to be diffused out through the copper oxide film. From the discussions above, it could be concluded that the oxide film was formed and grown by the copper ion diffusion first and then the reaction with any oxidant in the post-CMP cleaning solution.

• Phonetics and Speech Sciences
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• v.12 no.2
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• pp.63-72
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• 2020

This study aims to develop a video-based smart utterance deep analyser (SUDA) application that analyzes semiautomatically the utterances that child and mother produce during interactions over time. SUDA runs on the platform of Android, iPhones, and tablet PCs, and allows video recording and uploading to server. In this device, user modes are divided into three modes: expert mode, general mode and manager mode. In the expert mode which is useful for speech and language evaluation, the subject's utterances are analyzed semi-automatically by measuring speech and language factors such as disfluency, morpheme, syllable, word, articulation rate and response time, etc. In the general mode, the outcome of utterance analysis is provided in a graph form, and the manger mode is accessed only to the administrator controlling the entire system, such as utterance analysis and video deletion. SUDA helps to reduce clinicians' and researchers' work burden by saving time for utterance analysis. It also helps parents to receive detailed information about speech and language development of their child easily. Further, this device will contribute to building a big longitudinal data enough to explore predictors of stuttering recovery and persistence.

• Journal of The Korean Astronomical Society
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• v.36 no.3
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• pp.89-95
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• 2003

Observations of dark matter dominated dwarf and low surface brightness disk galaxies favor density profiles with a flat-density core, while cold dark matter (CDM) N-body simulations form halos with central cusps, instead. This apparent discrepancy has motivated a re-examination of the microscopic nature of the dark matter in order to explain the observed halo profiles, including the suggestion that CDM has a non-gravitational self-interaction. We study the formation and evolution of self-interacting dark matter (SIDM) halos. We find analytical, fully cosmological similarity solutions for their dynamics, which take proper account of the collisional interaction of SIDM particles, based on a fluid approximation derived from the Boltzmann equation. The SIDM particles scatter each other elastically, which results in an effective thermal conductivity that heats the halo core and flattens its density profile. These similarity solutions are relevant to galactic and cluster halo formation in the CDM model. We assume that the local density maximum which serves as the progenitor of the halo has an initial mass profile ${\delta}M / M {\propto} M^{-{\epsilon}$, as in the familiar secondary infall model. If $\epsilon$ = 1/6, SIDM halos will evolve self-similarly, with a cold, supersonic infall which is terminated by a strong accretion shock. Different solutions arise for different values of the dimensionless collisionality parameter, $Q {\equiv}{\sigma}p_br_s$, where $\sigma$ is the SIDM particle scattering cross section per unit mass, $p_b$ is the cosmic mean density, and $r_s$ is the shock radius. For all these solutions, a flat-density, isothermal core is present which grows in size as a fixed fraction of $r_s$. We find two different regimes for these solutions: 1) for $Q < Q_{th}({\simeq} 7.35{\times} 10^{-4}$), the core density decreases and core size increases as Q increases; 2) for $Q > Q_{th}$, the core density increases and core size decreases as Q increases. Our similarity solutions are in good agreement with previous results of N-body simulation of SIDM halos, which correspond to the low-Q regime, for which SIDM halo profiles match the observed galactic rotation curves if $Q {\~} [8.4 {\times}10^{-4} - 4.9 {\times} 10^{-2}]Q_{th}$, or ${\sigma}{\~} [0.56 - 5.6] cm^2g{-1}$. These similarity solutions also show that, as $Q {\to}{\infty}$, the central density acquires a singular profile, in agreement with some earlier simulation results which approximated the effects of SIDM collisionality by considering an ordinary fluid without conductivity, i.e. the limit of mean free path ${\lambda}_{mfp}{\to} 0$. The intermediate regime where $Q {\~} [18.6 - 231]Q_{th}$ or ${\sigma}{\~} [1.2{\times}10^4 - 2.7{\times}10^4] cm^2g{-1}$, for which we find flat-density cores comparable to those of the low-Q solutions preferred to make SIDM halos match halo observations, has not previously been identified. Further study of this regime is warranted.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.3
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• pp.225-232
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• 2004

The human history has progressed closely related to land. Mankind started land administration as a tool of governance to make land the object of imposing taxation as well as developing the land administration as a concept of securing property rights. People have drawn boundary lines on the ground to form a land parcel according to the usage and/or ownership. Furthermore, the land administration has been developed as a registering system of cadastral records fer the public announcement of fixed boundary instead of changeable ground boundary. Currently the citizens demand the provision of accurate and diverse information on the land which is assessed to has high property value encouraged by the rapid development in the post-industrial society today. However, even though the fact that the Korean cadastral registers produced during the Land Investigation Project are still practically in use causes land-related disputes and promotes public mistrust because of the changed boundaries by parcel mutation, the expansion and contraction of map sheets and the quality deterioration and damage of map paper, but the ultimate resolution is not yet made so far. The distance difference between boundary points are compared and analyzed using TS surveying method in the research as a methodology to resolve the boundary inconsistency, the current problem of cadastral records. Consequently, I'd say that the new surveying method of registering the coordinates of real ground boundary has been regarded as more efficient than considering the matter on the map regardless of urban or rural areas.

• Journal of Preventive Medicine and Public Health
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• v.30 no.2 s.57
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• pp.428-436
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• 1997

Objectives : The purpose of this paper is to estimate the completeness of the Korean Medical Insurance Data in childhood asthma. Methods : Capture-recapture method was used to estimate the prevalence of childhood asthma and case ascertainment rate(completeness) of Korean Medical Insurance Data using two source model, 'Korean Medical Insurance Committee Data (KMICD)' and 'Nationwide Study of Asthma and Allergies in Korean Children'. The asthma cases were restricted to those who were born from 1981 to 1989 and were identified by their Resident Register Number. Asthma cases in Korean Medical Insurance Data were defined as cases coded by ICD-9 493 and ICD-10 J45. In 'Nationwide Study of Asthma and Allergies in Korean Children', asthma cases were defined as the children who had been diagnosed asthma and had experienced symptoms of asthma during the past 12 months. The defined cases in two data sources were matched by 13 digits Resident Register Number. The numbers of matched patients in two data sources were 245 of 32,825 eligible total subjects. Chapman and Wittes' nearly unbiased estimation was used for capture-recapture analysis of two data sources. Results : Observed prevalence rate of childhood asthma was 5.3% and estimated prevalence rate by capture-recapture analysis was 11.6%. The highest prevalence rate was observed in 6-7 age group and the older the rate decreased. The completeness (the proportion of cases ascertained by KMICD to the total observed cases by two data sources) was 20.6%, and ranged form 10.8% to 28.8% by area. Conclusions : Invalid diagnosis of cases might overestimate the prevalence of child-hood asthma and might underestimate the completeness of Korean Medical Insurance Committee Data in this study.

• Korean Journal of Health Education and Promotion
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• v.19 no.2
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• pp.23-43
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• 2002

Purpose: The purpose of this study is to examine and analyse factors related to the actual status and practice of breast-feeding during an infant period to grasp elements detrimental to breast-feeding and, therefore, provide basic information useful for its effective practice and encouragement. Method: From April 1 to June 30, 2001, this study was carried out with the mothers of 337 who were 6 months old, as of the surveyed date, of infants born in 2002 and registered in Seongju-gun Public Health Center, Gyeongsangbug-do Province. The method for its survey included both of the visiting and telephone interviews, and questions were mainly about the mothers' general characteristics(3 questions), infants' general characteristics(3 questions), environmental characteristics of infant delivery( 4 questions), support to breast-feeding(4 questions), understanding of breast-feeding(5 questions), and feeding type during the 1 to 6-month period after birth. Result: 1. The feeding type during the I-month period after birth showed that the breast-feeding accounted for 42.4%, which was higher than dry milk-feeding(30%) or mixed milk-feeding(26.8%). However, it began to be lower than the dry milk-feeding from the 2-month period after birth. During the 6-month period, the breast-feeding accounted for 28.6% which was lower than 56.5% of the dry milk-feeding. 2. The mothers who were encouraged by their delivery clinic to and were educated to breast-feed infants accounted for 55.4% and 41.4%, respectively, which were relatively low. The understanding of breast-feeding indicated that the responses were positive from the view point of mother ＆ infant health, but negative from mother's physical form. 3. It was shown that the lower the educational background of mother(p〈0.05) and the higher the unemployment of mother(p〈0.001), the higher the positive understanding of breast-feeding, and that the higher the entire support to breast-feeding, the more positive their understanding. 4. It was also shown that the lower the educational background of mother(p〈0.05), the higher the unemployment of mother(p〈0.001), the more the experience in breast-feeding at a delivery clinic(p〈0.01) and the faster the initial feeding(p〈0.001), the higher the rate of breast-feeding. 5. The factor having an effect on breast-feeding included a delivery clinic's encouragement to breast-feed(p〈0.001), understanding of breast-feeding(p〈0.01), father's comment on feeding method(p〈0.05) and mother's employment(p〈0.05). Discussion: In order to encourage the breast-feeding, as shown above, it is required, fist of all, to offer pregnant women an education about importance and excellence of breast-feeding and its appropriate method before delivery in advance to result in a positive comprehension of the breast-feeding. To do that, both the publicity activities and program development designed to encourage the breast-feeding must be performed in advance at the government level. In addition to that, the mother-infant space as ‘rooming-in’ available for breast-feeding immediately after delivery must be prepared on the basis of legal and administrative support. Finally, female employees' leave after childbirth must be performed for the purpose of productive welfare and circumstances also be prepared for breast-feeding, such as a children's home at work.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.314-320
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• 2001

In this paper, the properties of an expansive agent (CaO-CaS $O_4$) for dry shrinkage compensation were investigated by a series of experimental program, which might be used at On-Dol heating system as mortar type. The expansion principle of the CaO-CaS $O_4$ was mainly verified. As a result of this study, the correlation between the content of the expansive agent and the compressive strength was obtained in the form of exponential function(Y = A $e^{-x}$), showing that as the content of expansive agent increased as the expansion performance with the compressive strength increased by only a certain amount. Also, as a results of the analysis of a correlation between the expansive performance and the chemical properties which generally accompanied a part of quality management in manufacturing the expensive cement, the expansive performance was relative to only the contents of the F-CaO among chemical properties(Blaine, +44$\mu\textrm{m}$R, F-CaO, S $O_3$,L.O.I). And it was clarified that the results were relative to the second order function, showing that if the contents of the F-CaO increased the expansive performance Increased.d.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.173-182
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• 1996

An experimental research was carried out to investigate the effect of thc compressive strength of concrete on the stirrup effectiveness in shear behavior of concrete beams. For this purpose. total 24 beams of section dimension of $300{\times}600mm$ were tested: 4 specimens without web reinforcement and 20 specimens with web reinforcement in the form of vertical stirrups. Main variables were two levels(norma1 and high strength) of the compressive strength of concrete and six types of t h e shear rcinfor.cement ratios. Prior to experiment, for given sections and assumed material constants, the reference shear reinforcement ratio(${\rho}_vACI$) which leads to the flexure failure using the provisions of the ACI Building Code(AC1 318-95) was calculated. and the shear reinforcement ratios were relatively selected from the value of ${\rho}_vACI$. From test results, it was shown that thc safety factor of ACI eyuation for p1,ediction of shear strength was decreased with increasing the compressive strength of concrete in beams without stirrups. However. it was observed that as the amount of' stirrup is increased, the safety factor for high strength conci,ete beams with high stirrup ratio is ensured more than that for normal strength concrete beams. Therefore i t appears that the stirrup effectiveness of high strength concrete beams is greater than that of normal strength concrete beams.

• Journal of the Economic Geographical Society of Korea
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• v.13 no.1
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• pp.111-125
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• 2010

For a shift to a new paradigm that allows restoring solidarity among class, gender, and race, it is necessary to closely investigate the differences between Marxist view and poststructuralist view which provide theoretical basis for labor movement and for feminist movement, respectively. However, little effort has been devoted to this task. This paper critically compares two best wellknown geographers; Harvey's class-centered theory and Gibson-Graham's post-structuralist feminist approach by focusing on their understandings of "difference". David Harvey argues that racial/gender discrimination is another form of class-exploitation and puts priority on the solidarity based on the commonality of labor. On the contrary Gibson-Graham argues that the privileging of class above all else marginalizes other political dimension, and proposes the deconstruction of hegemonic discourse of capitalism and the construction of "community economies", Based on the critical survey of both theories, I propose that understanding the role that spatiality plays in capital accumulation process is the key to compromise two different approaches.