• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.8 no.2
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• pp.242-255
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• 1997

Characteristics of attention deficit of attention-deficit hyperactivity disorder(ADHD) were investigated by administering six computerized attention tests of Vienna Test System and four neuropsychological tests to children aged 6-12, with ADHD(n=21) and age-matched normal control children(n=22). The findings indicated that ADHD children show lower level of vigilance, more decline of performance in vigilance task on time, and impaired preparedness to response. They also have selective attention deficit on monitoring tasks, but did not have sustained attention deficit compared with normal control children. On the tasks wich overload their information processing capacity, ADHD children show more impulsive response pattern than normal control children. The performance of ADHD was worse than control on the neuropsychological tests sensitive to frontal lobe dysfunction. The presense 'These' attention deficits supports the theory that the defect of ADHD is due to the dysfunction of more than one brain region, including brain stem reticular formation and frontal lobe.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.98-103
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• 2013

In this work, we investigated the enhanced performance of IZO-based TFTs with $HfSiO_x$ gate insulators. Four types of $HfSiO_x$ gate insulators using different diposition powers were deposited by co-sputtering $HfO_2$ and Si target. To simplify the processing sequences, all of the layers composing of TFTs were deposited by rf-magnetron sputtering method using patterned shadow-masks without any intentional heating of substrate and subsequent thermal annealing. The four different $HfSiO_x$ structural properties were investigated x-ray diffraction(XRD), atomic force microscopy(AFM) and also analyzed the electrical characteristics. There were some noticeable differences depending on the composition of the $HfO_2$ and Si combination. The TFT based on $HfSiO_x$ gate insulator with $HfO_2$(100W)-Si(100W) showed the best results with a field effect mobility of 2.0[$cm^2/V{\cdot}s$], a threshold voltage of -0.5[V], an on/off ratio of 5.89E+05 and RMS of 0.26[nm]. This show that the composition of the $HfO_2$ and Si is an important factor in an $HfSiO_x$ insulator. In addition, the effective bonding of $HfO_2$ and Si reduced the defects in the insulator bulk and also improved the interface quality between the channel and the gate insulator.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.19-25
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• 2011

The size reduction of the semiconductor chip and the improvement of the electrical performance have been enabled through the introduction of the Cu/Low-K process in modern electronic industries. However, Cu/Low-K has a disadvantage of the physical properties that is weaker than materials used for existing semiconductor manufacture process. It causes many problems in chip manufacturing and package processes. Especially, the delamination between the Cu layer and the low-K dielectric layer is a main defect after the temperature cycles. Since the Cu/Low-K layer is located on the top of the pad of the flip chip, the stress on the flip chip affects the Cu/Low-K layer directly. Therefore, it is needed to improve the underfill process or materials. Especially, it becomes very important to select the underfill to decrease the stress at the flip-chip and to protect the solder bump. We have solved the delamination problem in a 90 nm Cu/Low-K flip-chip package after the temperature cycle by selecting an appropriate underfill.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.4
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• pp.263-270
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• 2020

This study evaluates the structural behavior of connected long-span beams applied for excavation in urban areas with a narrow street. Generally, the reliability of the connection is reduced owing to the defect of the upper flange in the connection. An improved connection part was developed to complement the defects in the connected long-span beam. A finite element analysis based on a commercial program, ABAQUS, was employed to evaluate the behavior of the improved connection part. A numerical analysis model was proposed to analyze the high-strength bolt connection and the composite behavior of steel and concrete applied to the improved connection. The suitability of the proposed numerical analysis was verified by comparing the experimental and numerical analysis results of the references. Using the proposed numerical analysis method, the improved and general connections were analyzed and compared with each other. The stress distribution and elastic-plastic behavior of the long-span beam were analyzed numerically. The analysis confirmed that 25% of the compressive stress was improved, resulting in the improvement of structural safety and performance.

• Management & Information Systems Review
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• v.28 no.3
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• pp.161-189
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• 2009

The sub-prime crisis led to the collapse of US investment banks which were considered highly competitive during the Asian Financial Crisis. The event gave us a lesson on importance of the financial supervision. Additionally concerns rise over the fact that the role model of the Capital Market Law, created for the purpose of developing the capital market, is the US investment banks. This paper investigates if the prudential regulations, among them especially the capital regulation, are able to prevent the risk the arises from Korean financial firms operating investment bank business. The current capital requirement regulation, Net Capital Ratio(NCR), is not sufficient, because it's nature of being a ratio makes the NCR ineffective when assets and liabilities are concurrently rising. We also verified the internal model which measured the market risk, by comparing the US investment and Korean banks' diversification effect. The result of the test is that it is difficult to conclude the internal model has a critical defect. This paper's contribution is that it is not sufficient use only the capital regulation in supervising financial markets.

• Korean Journal of Microbiology
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• v.52 no.4
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• pp.487-494
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• 2016

In Saccharomyces cerevisiae, Paf1 complex consists of five proteins, and they are structurally and functionally well conserved in yeast, fruit fly, plants, and human. With binding to RNA polymerase II from transcription start site to termination site, Paf1 complex functions as a platform for recruiting many types of transcription factors to RNA polymerase II. Paf1 complex contributes to H2B ubiquitination and indirectly influences on H3K4 di- and tri-methylation by histone crosstalk. But the individual effects of five components in Paf1 complex on these two histone modifications including H2B ubiquitination and H3K4 methylation largely remained to be identified. In this study, we constructed the single-gene knockout mutants of each Paf1 complex component and observed H3K4 mono-, di-, and trimethylation as well as H2B ubiquitination in these mutants. Interestingly, in each ${\Delta}paf1$, ${\Delta}rtf1$, and ${\Delta}ctr9$ strain, we observed the dramatic defect in H3K4 monomethylation, which is independent of H2B ubiquitination, as well as H3K4 di- and trimethylation. However, the protein level of Set1, which is methyltransferase for H3K4, was not changed in these mutants. This suggests that Paf1 complex may directly influence on H3K4 methylation by directly regulating the activity of Set1 or the stability of Set1 complex in an H2B ubiquitination independent manner.

• Journal of Chest Surgery
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• v.28 no.6
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• pp.571-578
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• 1995

Rastelli operation in which right ventricle[RV and pulmonary artery[PA is connected with an artificial graft is effective in increasing the pulmonary blood flow in certain types of congenital heart disease but, in many, it requires a reoperation because of the relative stenosis of graft that develops as the patients become old. The purpose of this study is to evaluate the various factors which many influence the long term outcome of such patients following a Rastelli operation. A total of 47 patients underwent a Rastelli operation during a 15 year period between November, 1978 and October 1993. The mean follow-up period is 76.1 51.3 months.1 Among the 47 patients, a valved conduit was used in 30[63.8% , and non-valved conduit in 17[36.2% patients. In the 8 patients[17.0% who died postoperatively, a valved conduit was used in 5 [16.6% and a non-valved conduit in 3[17.6% . There was no statistical difference in mortality between the 2 groups. There was a good linear correlation between the body surface area[X and the conduit size[Y [Y=3.86X + 14.6, R=0.55, P=0.01 .2 Ten patients underwent replacement of the conduit during the follow-up period. The type of conduit used and the frequency of subsequent replacement were as follows: Ionescu-Shiley, valved-33.3%, Carpentier-Edwards, valved-30.8%, Hancock, valved-80% and non-valved conduit-9.1%. The median period free of reoperation was 110 months for the valved and 79 months for the non-valved group, there being no statistical difference between the 2 groups. 3 The patients who did not require reoperation are all doing well [New York Heart Association Functional Classification: Class I . Pressure gradient between the RV and the PA was 20 mmHg in 10 randomly selected patients who did not require reoperation and 92 9 mmHg in 10 patients who did require reoperation.4 In the 10 patients who underwent a conduit replacement procedure.5 Among patients undergoing reoperation, 2 died from endocarditis.The remaining 8 patients are doing well without limitation in physical activity at a mean follow-up period of 32.7 33.9 months [range 2 to 89 months . 6 At 5, 7, and 10 years, the reoperation-free rates among all patients were 96%, 91% and 29% and the survival rates were 82%, 82% and 71%. In conclusion, Rastelli operation is an effective procedure in ameliorating symptoms in a select group of patients with congenital heart disease. Because of the inherent nature of relative graft stenosis and degeneration, a long-term follow-up is required under the proper selection of the graft material.

• Journal of Korean Foot and Ankle Society
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• v.6 no.1
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• pp.66-72
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• 2002

Purpose: To evaluate the overall results and its major affecting factors(athlete/associated injury) of modified Brostrom procedure for chronic ankle lateral instability. Materials and Methods: Fifty-one patients (51 ankles) with chronic ankle lateral instability were sub-grouped athletes and non-athletes and again sub-grouped with associated injury and without associated injury. Associated injuries were osteochondral defect(6), peroneal tendon abnormality(10), os subfibularae(4), os subtibialae(4), anterior impingement(5) and loose body(2). The overall surgical results were evaluated and also see whether or not athletes and associated injury affect the result. Result: Of the 51 operations performed, there were 39 excellent, 8 good and 4 fair as a whole. Of the 24 athletes operated, there were 19 excellent, 3 good, and 2 fair. Among the 27 non-athletes, there were 20 excellent, 5 good and 2 fair results. The average time to ordinary life in the non-athlete group was 2.5 months and average time to sports activity in the athlete was 4.5 months postoperatively. Those who didn't have any associated injury had all excellent result, on the contrary, those who had associated injuries, 14 excellent, 8 good and 4 fair results. All the fair results were associated with osteochondral lesion of talus. Whether or not the patient is athlete does not affect the surgical results, but whether or not there were associated injuries does affect the surgical results. Conclusion: Modified Brostrom procedure for chronic ankle lateral instability itself is an excellent to good operation. This procedure can be used in athletic populations who need high demand of sports activity. But chronic ankle lateral instability with associated injury group showed variable, less satisfactory results than those without associated injury. Careful preoperative and intraoperative examination should be done to find out the associated injury with chronic ankle lateral instability.

• Journal of Periodontal and Implant Science
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• v.33 no.1
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• pp.13-26
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• 2003

Periodontal regeneration therapy with bone-substituting materials has gained favorable clinical efficacy by enhancing osseous regeneration in periodontal bony defect. As bone-substituting materials, bone powder, calcium phosphate ceramic, modified forms of hydroxyapatite, and hard tissue replacement polymer have demonstrated their periodontal bony regenerative potency. Bone-substituting materials should fulfill several requirements such as biocompatibility, osteogenecity, malleability, biodegradability. The purpose of this study was to investigate biocompatibility, osteo-conduction capacity and biodegradability of $Na_2O$, $K_2O$ added calcium metaphosphate(CMP). Beta CMP was obtained by thermal treatment of anhydrous $Ca_2(H_2PO_4)_2$. $Na_2O$ and $K_2O$ were added to CMP. The change of weight of pure CMP, $Na_2O$-CMP, and $K_2O$-CMP in Tris-buffer solution and simulated body fluid for 30 days was measured. Twenty four Newzealand white rabbits were used in negative control, positive control(Bio-Oss), pure CMP group, 5% $Na_2$-CMP group, 10% $Na_2O$-CMP goup, and 5% $K_2O$-CMP group. In each group, graft materials were placed in right and left parietal bone defects(diameter 10mm) of rabbit. The animals were sacrificed at 3 months and 6 months after implantation of the graft materials. Degree of biodegradability of $K_2O$ or $Na_2O$ added CMP was greater than that of pure CMP in experimental condition. All experimental sites were healed with no clinical evidence of inflammatory response to all CMP implants. Histologic observations revealed that all CMP grafts were very biocompatible and osseous conductive, and that in $K_2O$-CMP or $Na_2O$-CMP implanted sites, there was biodegradable pattern, and that in site of new bone formation, there was no significant difference between all CMP group and DPBB(Bio-Oss) group. From this result, it was suggested that all experimental CMP group graft materials were able to use as an available bone substitution.

• Journal of Periodontal and Implant Science
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• v.39 no.sup2
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• pp.213-222
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• 2009

Purpose: Recently, interest in chitosan has increased due to its excellent biological properties such as biocompatibility, antibacterial effect, and rapid healing capacity. On the other hand, hydroxyapatite is used as a bone substitute in the fields of orthopedics and dentistry. The hydroxyapatite-chitosan (HA-CS) complex containing hydroxyapatite nanoparticles was developed for synergy of both biomaterials. The objective of this study was to evaluate the effect of hydroxyapatite (HA)-chitosan (CS) membrane on bone regeneration in the rat calvarial defect. Methods: Eight-millimeter critical-sized calvarial defects were created in 70 male Sprague-Dawley rats. The animals were divided into 7 groups of 10 animals and received either 1) chitosan (CS) 100% membrane, 2) hydroxyapatite (HA) 30%/CS 70% membrane, 3) HA 30%/CS 70%, pressed membrane, 4) HA 40%/CS 60% membrane, 5) HA 50%/CS 50% membrane, 6) HA 50%/CS 50%, pressed membrane, or 7) a sham . surgery control. The amount of newly formed bone from the surface of the rat calvarial defects was measured using histomorphometry, following 2- or 8- week healing intervals. Results: Surgical implantation of the HA - CS membrane resulted in enhanced local bone formation at both 2 and 8 weeks compared to the control group. The HA - CS membrane would be significantly more effective than the chitosan membrane in early bone formation. Conclusions: Concerning the advantages of biomaterials, the HA-CS membrane would be an effective biomaterial for regeneration of periodontal bone. Further studies will be required to improve the mechanical properties to develop a more rigid scaffold for the HA-CS membrane.