• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.3
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• pp.53-62
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• 1986

For the research on the fatigue fracture behavior in the welded joints of steel structures, base metal specimens and welded ones were selected, and the direct fatigue tests were carried out. Thereafter, fatigue-life (S-N) curves, plastic strain-number of cycles (${\varepsilon}_p$-N) curve, the extrapolated fatigue-life (${\varepsilon}_p$-$N_c$) curve, and da/dN-${\Delta}K$ curves were plotted. By these results the followings were obtained. It was shown that the ratio of fatigue strength at $2{\times}10^6$ cycles of the welded specimen to that of the base metal one was 0.6, and that 0.72 for the base metal and 0.65 for the welded one were the ratio of fatigue strength at $2{\times}10^6$ cycles to yielding stress. The S-N curve for the welded specimen was separated into two sections, the low gradient section and the steep section. As this result, it was shown that the more stress became to reduce, the more the reduction of fatigue strength became to be great. It was shown that fatigue strength at $2{\times}10^6$ cycles from this case was about 83 % of that from the S-N curve plotted with one section. It was thought that the reason was that weld flaw acted greatly on the fatigue strength within the low stress range. It was shown that at the instart of crack initiation plastic strain increased abrupt1y in the case of the welded specimen more than the case of the base metal specimen, and increased abruptly in the upper stress range in both cases. It was shown that the experimental constant ${\alpha}$, 0.42, in the base metal nearly accorded with Manson-Coffin's result, but this made a great difference with the case in the welded specimen. It was thought that it was due to the abrupt change of plastic strain and the influence of weld flaw.

• Journal of Sensor Science and Technology
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• v.12 no.6
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• pp.273-281
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• 2003

A stoichiometric mixture for $CdIn_2Te_4$ single crystal was prepared from horizontal electric furnace. The $CdIn_2Te_4$ single crystal was grown in the three-stage vertical electric furnace by using Bridgeman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. The (001) growth plane of oriented $CdIn_2Te_4$ single crystal was confirmed from back-reflection Laue patterns. The carrier density and mobility of $CdIn_2Te_4$ single crystal measured with Hall effect by van der Pauw method are $8.61{\times}10^{16}\;cm^{-3}$ and $242\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CdIn_2Te_4$ single crystal obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.4750\;eV-(7.69{\times}10^{-3}\;eV)T^2/(T+2147)$. After the as-grown $CdIn_2Te_4$ single crystal was annealed in Cd-, In-, and Te-atmospheres, the origin of point defects of $CdIn_2Te_4$ single crystal has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Te}$, $Cd_{int}$, and $V_{Cd}$, $Te_{int}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Cd-atmosphere converted $CdIn_2Te_4$ single crystal to an optical n-type. Also, we confirmed that In in $CdIn_2Te_4$ did not form the native defects because In in $CdIn_2Te_4$ single crystal existed in the form of stable bonds.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.320-327
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• 2009

Statement of Problem: Although many efforts have been continually made to estimate long term prognosis of removable partial dentures, the complication of removable partial dentures was still found because of inaccurate fabrication procedure and improper maintenance care. Purpose: The purpose of this study was to evaluate the clinical status of removable partial dentures. Material and methods: A total of 112 individuals with 153 removable partial dentures (35 - 87 years, 64 women and 48 men) were examined by intra-oral examination, diagnostic cast and radiographic examination. Results and conclusion: The results of this study were as follows: 1. Length of service of removable partial dentures was $5.3{\pm}4.3$ years (mean), 4.0 years (median). 2. A total of 45 removable partial dentures were considered failures. The loss of 18 abutments of 369 was founded. 3. Type of arch, Kennedy classification and type of opposite dentition were found to have no influence on longevity and success rate of removable partial dentures (P > .05). 4. Most common major connector was the palatal plate in maxilla and the number of lingual bar and linguoplate designed in mandible were similar. 5. The circumferential type retainer was the most commonly used retainer. 6. Sixty-three percent of the class I and II removable partial dentures incorporated indirect retention into the design. 7. Approximately 81% of the removable partial dentures had at least one defect. Excessive wear of posterior teeth (27.9%), lack of integrity (23.2%), lack of stability (22.6%) were frequent defects of removable partial dentures.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.519-527
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• 2016

The demand of construction risk analysis is rapidly increased to improve the competitiveness of construction companies and the sound management of the construction project. However, estimating the amount and uncertainty of the risk is difficult due to the wide range of risks in the construction industry. Moreover, most of the research on risk management of construction risk is only focused on the causes of risk without separate the internal and external risk. This study statistically analysis the internal risk and external risk based on the accidents cases which are caused at construction sites to define the difference and importances of the risk. An accident cause analysis and T-test analysis are carried out to reach the goal of study. The results of the study are expected to be used as a guideline of construction project risk analysis.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.562-570
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• 2008

Amelogenesis imperfecta is a group of hereditary defects of enamel, unassociated with any other generalized defects. It is classified into 14 subtypes according to different clinical and genetic features. According to its clinical features, it is classified into hypoplastic type, hypocalcified type and hypomaturation type. However, these features tend to co-exist often. Dental features associated with amelogenesis imperfecta include quantitative and qualitative enamel deficiencies, pulpal calcification, root malformations, abnormal eruption, impaction of permanent teeth, progressive resorption of root and crown, congenital missing teeth and anterior and posterior open bite occlusions. The first case patient is a 16 month-old child with discoloration of deciduous teeth. All of her deciduous and permanent dentition has shown amelogenesis imperfecta. The restorational, orthodontic and recent prosthodontic treatments have been completed. Another patient is a 9 year and 3 month-old child with amelogenesis imperfecta in both deciduous and permanent dentition. The restoration has been done and the prosthodontic treatment is planned after the completion of growth. Above cases indicate that amelogenesis imperfecta occurs both in deciduous and permanent dentition, and it requires the long term treatment and care.

• The KIPS Transactions:PartB
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• v.10B no.6
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• pp.657-664
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• 2003

Reliable tracking of moving humans is essential to motion estimation, video surveillance and human-computer interface. This paper presents a new approach to human motion tracking that combines appearance-based and model-based techniques. Monocular color video is processed at both pixel level and object level. At the pixel level, a Gaussian mixture model is used to train and classily individual pixel colors. At the object level, a 3D human body model projected on a 2D image plane is used to fit the image data. Our method does not use inverse kinematics due to the singularity problem. While many others use stochastic sampling for model-based motion tracking, our method is purely dependent on nonlinear programming. We convert the human motion tracking problem into a nonlinear programming problem. A cost function for parameter optimization is used to estimate the degree of the overlapping between the foreground input image silhouette and a projected 3D model body silhouette. The overlapping is computed using computational geometry by converting a set of pixels from the image domain to a polygon in the real projection plane domain. Our method is used to recognize various human motions. Motion tracking results from video sequences are very encouraging.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.134-141
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• 2011

There have been increased economic and societal demands to continuously monitor the integrity and long-term deterioration of civil infrastructures to ensure their safety and adequate performance throughout their life span. However, it is very difficult to continuously monitor the structural condition of the pipeline structures because those are placed underground and connected each other complexly, although pipeline structures are core underground infrastructures which transport primary sources. Moreover, damage can occur at several scales from micro-cracking to buckling or loose bolts in the pipeline structures. In this study, guided wave measurement can be achieved with a self-sensing circuit using a piezoelectric active sensor. In this self sensing system, a specific frequency-induced structural wavelet response is obtained from the self-sensed guided wave measurement. To classify the multiple types of structural damage, supervised learning-based statistical pattern recognition was implemented using the damage indices extracted from the guided wave features. Different types of structural damage artificially inflicted on a pipeline system were investigated to verify the effectiveness of the proposed SHM approach.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.654-660
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• 2001

Dentinogenesis imperfecta is an example of an inheritable dentinal defect originating during the histodifferentiation stage of tooth development, with involvement of the primary and permanent teeth. Shields, Bixler and El-Kafrawy proposed three types of Dentinogenesis imperfecta : Type I, II, III. Witkop reported a prevalence of 1 in 8000 with the trait, and no significant difference between male and female. Affected teeth have red-brown discoloration often with distinctive wearness of occlusal surface of posterior teeth and incisal surface of anterior teeth. Once enamel seperated from underlying defective dentin, the dentin demonstrates significantly acclerated attrision. Radiographically, the teeth have thin roots, bulbous crown, cervical constriction, and obliteration of the root canals and pulp chambers. In primary dentition periapical lesions or multiple root fractures are often observed. In successive generations the phenotypes of discoloration and wearness of teeth occurred, and one of the patient's subships, 10 year-old sister, showed general discoloration of her teeth and mild wearness. In this case, a 4 year-old male reported to the Yonsei University Pedodontics clinic, with a chief complaint of discolored teeth. The teeth showed generally yellowish-brown discoloration and moderate wearness. In radiographic features, obliteration of pulp, bulbous crown, and short roots were observed. It was diagnosed as Dentinogenesis imperfecta. The posterior teeth were restored with Stainless Steel Crown, and defective incisors including left upper primary central incisor which was extracted due to a root fracture with Open-faced Stainless Steel crown.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.4
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• pp.79-86
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• 2016

About 75% of software security incidents are caused by software vulnerability. In addition, the after-market repairing cost of the software is higher by more than 30 times than that in the design stage. In this background, the secure coding has been proposed as one of the ways to solve this kind of maintenance problems. Various institutions have addressed the weakness patterns of the standard software. A new Korean programming language Saesark has been proposed to resolve the security weakness on the language level. However, the previous study on Saesark can not resolve the security weakness caused by the API. This paper proposes a way to resolve the security weakness due to the API. It adopts a static analyzer inspecting dangerous methods. It classifies the dangerous methods of the API into two groups: the methods of using tainted data and those accepting in-flowing tainted data. It analyses the security weakness in four steps: searching for the dangerous methods, configuring a call graph, navigating a path between the method for in-flowing tainted data and that uses tainted data on the call graph, and reporting the security weakness detected. To measure the effectiveness of this method, two experiments have been performed on the new version of Saesark adopting the static analysis. The first experiment is the comparison of it with the previous version of Saesark according to the Java Secure Coding Guide. The second experiment is the comparison of the improved Saesark with FindBugs, a Java program vulnerability analysis tool. According to the result, the improved Saesark is 15% more safe than the previous version of Saesark and the F-measure of it 68%, which shows the improvement of 9% point compared to 59%, that of FindBugs.

• Journal of Korean Philosophical Society
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• v.123
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• pp.87-110
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• 2012

The kitsch was emerged from the people's cultural desire in the conditions of the various duplicating technology, the capital economy system, and the civil revolution in the western modern mass society. But it is underestimated constantly because of the conspicious consumption and the aesthetic inadequacy. Even though some kitsches are elevated to the 'kitsch arts' in the historical description of the modern arts, still the most of kitsches are remained as 'just kitsches' and excluded from the aesthetic research according to the double standard. In this essay, I research for whether anti-kitsch theory is convincing theoretically and practically. Anti-kitsch theory criticizes the kitsch on the basis of the modernist aesthetics, in which the 'fine art' provokes the aesthetic pleasure in the disinterested contemplation. But kitsch purposes for the sensual gratification and the sentimentality. So the anti-kitish theorists conclude that the kitsch is the bad taste. In critically analyzing the argumentation of Greenberg's. Kaplan's and $C{\tilde{a}}linescu^{\prime}s$, I refute the privileged prejudice of the ideal critic. They don't justify the criteria of the classification of 'art'/ 'kitsch'. They supplement the economical and the political grounds for the evaluative theory of the kitsch. But the argumentation of the kitsch is consumed conspicuously and results in the unlettered masses is not sufficient. People produce and enjoy the kitsches in the various ways. People envelope the genres, styles and media of the kitsches and they try to suggest the new horizon of the popular aesthetics. So anti-kitsch theories cannot be accepted because they adhere to the elitism and formalism. The exclusion of the kitsch is the derogation for people's taste. Also they didn't reflect the contemporary cultural practice and the aesthetic needs in the system of post-art. The alternative aesthetics of the kitsch is the topic of my next essay.