• The korean journal of orthodontics
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• v.36 no.6
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• pp.412-421
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• 2006

Objective: The result of finite element analysis depends on material properties, structural expression, density of element, and boundar or loading conditions. To represent proper elastic behavior, a finite element model was made using Hounsfield unit (HU) values in CT images. Methods: A 13 year 6 month old male was used as the subject. A 3 dimensional visualizing program, Mimics, was used to build a 3D object from the DICOM file which was acquired from the CT images. Model 1 was established by giving 24 material properties according to HU. Model 2 was constructed by the conventional method which provides 2 material properties. Protraction force of 500g was applied at a 45 degree downward angle from Frankfort horizontal (FH) plane. Results: Model 1 showed a more flexible response on the first premolar region which had more forward and downward movement of the maxillary anterior segment. Maxilla was bent on the sagittal plane and frontal plane. Model 2 revealed less movement in all directions. It moved downward on the anterior part and upward on the posterior part, which is clockwise rotation of the maxilla. Conclusion: These results signify that different outcomes of finite element analysis can occur according to the given material properties and it is recommended to use HU values for more accurate results.

• Korean Journal of Heritage: History & Science
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• v.48 no.1
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• pp.4-23
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• 2015

In the Buddhist paintings of the four devas, there is a change in the paper material of V aisravana(多聞天) in the early Joseon Dynasty. Until Goryeo Dynasty, Damuncheonwang, who holds a tower(塔) on the right side of Buddha was changed to the form which holds a mandolin(琵琶) in the early Joseon Dynasty. This change was first checked in Byeonsangdo in the Yuan period "The Avatamska Sutra(大方廣佛華嚴經, 1330~1336)", however the actual paper material change in the Buddhist painting is found first as a mural at the Tibetan temples, Cheolbangsa(哲蚌寺), Odunsa(吳屯寺), Baekgeosa(白居寺), which showed the change of tower which Vaisravaṇa held into mongoose. In Joseon Dynasty, also, new distribution of the four devas appeared first, which showed the change of paper material in the first floor roof-stones of Wongaksaji sipcheung seoktap, . However, the position of the four devas which held a tower and a mandolin consistently appear in the Buddhist paintings in the early Joseon Dynasty by mixing on the left and the right. This means the possibility that the paper material and the position of the four devas might be flexible in the early Joseon Dynasty. Just like reflecting this, painting image of the four devas in illustration of "saddharma-pundari-ka-$s{\bar{u}}tra$(Ming 1432, National Museum of Korea)" and illustration of "Jebulsejonyeorae-bosaljonjamyeongching-gagok(제불세존여래 보살존자명칭가곡, 1417)" has opposite position from each other. Therefore, the phenomenon in the Buddhist paintings of the early Joseon had a transitional characteristic which did not secure the fixed form of painting image by illustration of two copies where paper materials of the four devas were different, which characteristic can be said to be the characteristic of art in the transitional period.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.3
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• pp.23-33
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• 2012

Dynamic response measurements from natural excitation were carried out for three 18-story office buildings to determine their inherent properties. The beam-column frame system was adopted as a typical structural form, but a core wall was added to resist the lateral force more effectively, resulting in a mixed configuration. To extract modal parameters such as natural frequencies, mode shapes and damping ratios from a series of vibration records at each floor, the most advanced operational system identification methods based on frequency- and time-domain like FDD, pLSCF and SSI were applied. Extracted frequencies and mode shapes from the different identification methods showed a greater consistency for three buildings, however the three lower frequencies extracted were 1.2 to 1.7 times as stiff as those obtained using the initial FE models. Comparing the extracted fundamental periods with those estimated from the code equations and FE analysis, the FE analysis results showed the most flexible behavior, and the most simple equation that considers the building height as the only parameter correlated fairly well with test results. It is recognized that such a discrepancy arises from the fact that the present tests exclude the stiffness decreasing factors like concrete cracking, while the FE models ignore the stiffness increasing factors, such as the contribution of non-structural elements and the actual material properties used.

• Journal of Environmental Impact Assessment
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• v.24 no.3
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• pp.278-286
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• 2015

Pilot scale system was designed to identify the growth and movement of algae, depending on environmental changes(retention time, nutrient concentration, etc) in Gangjeong-Goryeong Weir of the Nakdong River. Considering the stability of algal culture and easy observation of algal growth, pilot scale system was made of transparent acrylic material(3 sets of flexible cylindrical water tanks with 1 m diameter and 4 m height). Auxiliary equipments include light intercepter, water inflow device for different water depth and storage of reclaimed water. The retention time was 2 days(before construction of weir; treatment 1), 8 days(after construction of weir, 2013; treatment 2) and 30 days(2014; treatment 3). According to the water temperature of treatment 1 were similar by depth, treatment 3 showed a difference between the surface(0 m) and bottom(4 m) more than $3^{\circ}C$. DO, pH showed relatively high in the surface than the bottom. Nutrients showed eutrophic condition in all experiments. The Chlrophyll-a concentration of the treatment 1 showed a relatively lower value than the Chlrophyll-a concentration of the treatment 2 and 3. Therefore, the retention time was considered to influence the growth of phytoplankton.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.1
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• pp.11-15
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• 2016

The organic light emitting diodes (OLEDs) have been studied as large flexible displays, light source and hard wares of internet of things. However, OLEDs show some drawbacks in terms of external environments due to the low work function of the metals and the reactive organic materials. In particular, the operation functions of the OLEDs tend to deteriorate rapidly by exposing the oxygen and moisture. So as to prevent it, domestic and overseas studies underway in various method such as ALD, PVD, CVD. But it has complex process and high cost. Therefore In order to protect devices from the external environments, it is important to develop the passivation thin films of low-cost and simple process which can prevent the devices from the penetration of the oxygen and moistures. In this study, to improve the reliability, passivation thin films were coated onto the green OLEDs by spin coating method and investigated the changes of the optical properties of the prepared devices at various doping concentrations of sodium alginate (SA). The passivation solutions were synthesized by using polyvinyl alcohol (PVA) host material with a dopant of SA which were added with the amounts of 10, 20 and 40 wt% into the PVA. As a result, the best barrier properties of the OLEDs were obtained for the samples with 40 wt% SA. Finally, the passivation films can be optimized by using the mixture solution of PVA and SA materials.

• Magazine of the Korea Concrete Institute
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• v.7 no.3
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• pp.199-210
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• 1995

We could say that the concrete filled steel tube structure is superior in the vlew of various structure properties as to promote improvement of structural capacity to dtmonstrate heterogeneous material properties interdependently. The compressive strength is increased by putting to tri axial stress because lateral expansion of concrete 1s confined by the steel tube, when concrete conflned by steel tube fall under centric axial load. Also, it have an advantage that decreasr of load carrying capacity 1s small, not occuring section deficiency due to protect falling piienornonon by co~nprrssion fallurc of concrete. So this study investigated for structural behaviors yroprrtiex of concwir. confined by steel tube throughout a series of experlmerit with kcy parxncter, such as diameter-to-thickness(D / t) ratio, strength of concrete as a study on properties of structural behaviors of confined concrete confined by circular steel tube( tri axial stress). Frorn the expcrment results, the obtained results, are surnrnarised as foliow. (1) The restraint effect of concrete by steel tube was presented significantly as the D /t ratio of steel tube and the strength of filled concrete decrease, and the confined concrete by circular steel tube was increased respectively twice as much as 4-7 in deformation capacity at the ultimate strength ,compared with those of non-confined concrete, so expected to increase flexible effect of concrete. (2) The emprical formula to predict the ultimate capacity of confined concrete by steel tube and concrete filled steel tube column using restraint coefficient of concrete were proposed.

• Journal of the Korean GEO-environmental Society
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• v.18 no.4
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• pp.13-21
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• 2017

Ballasted track has been used as track system for more than 100 years. Ballasted track has advantages of low construction cost, flexible maintenance, low noise and vibration, and so on. However, ballasted track leads to continuous settlement which causes maintenance. Recently, increase in speed, traffic volume, and weight of train requires more frequent maintenance. Fouling, well-known phenomenon of accumulation of fine materials due to intrusion of subgrade and breakage of ballast materials, expedites the settlement (i.e., irregular settlement) of track. Ground Penetrating Radar (GPR) can be one of non-destructive tools that can evaluate fouling level of ballast. In this paper, a gain function based on the attenuation characteristics of ballast material is suggested in conjunction with Hilbert transform. Lab box tests and full-scale tests indicate that the suggested method reasonably classifies clean, fouled layers, and subgrade. However, additional study to eliminate effect of sleeper and to include the scattering features of the electromagnetic wave in ballast voids should be required in order to enhance the accuracy.

• Journal of Korean Foot and Ankle Society
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• v.8 no.1
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• pp.39-45
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• 2004

Purpose: The author modified the technique of Grice-Green, for managing flexible flat foot, with severe hindfoot valgus and possible dorsiflexion more than $15^{\circ}$. The purpose of this study was to evaluate the efficacy and results of this modified technique. Material and Methods: Total of 6 patients, 11 cases of pes planovalgus were operatively managed with Modified Grice-Green procedure from Nov. 1996 to April 2002. Total 11 cases in 6 patients were managed; 9 cases in 5 males, 2 cases in one female. The average age of the patients were 7.3 years (5.1-13.3 years). Average follow up period was 3.9 years (1.2-6.7 years). Patients were evaluated preoperatively and at last follow up radiologically and clinically. Radiologic evaluation were done by measuring the talocalcaneal and talo-$1^{st}$ metatarsal angles with the anteroposterior view; and by measuring the talo-$1^{st}$ metatarsal angles with the lateral view. The clinical outcome were rated by subjective and objective improvement level. Results: On follow up, 9 cases were complete satisfied, 2 cases were satisfied with minor reservation and no case had major reservations or dissatisfaction. Objective results were rated as excellent in 9 cases, good in 2 cases. Average preoperative talo-calcaneal and talo-$1^{st}$ metatarsal angles on anteroposterior radiograms were $34.4^{\circ}$ ($16-40^{\circ}$) and $32^{\circ}$ ($8-48^{\circ}$) respectively; which postoperatively on last follow up were $20^{\circ}$ ($3-37^{\circ}$) and $15.6^{\circ}$ ($3-34^{\circ}$) respectively. Average Preoperative talo-$1^{st}$ metatarsal angle on lateral radiogram was $18.4^{\circ}$ ($6-30^{\circ}$); which postoperatively on last follow up was $6.7^{\circ}$ ($-6-17^{\circ}$). Conclusion: Modified Grice-Green operative procedure is effective and satisfactory procedure for planovalgus deformity in children. but for more accurate results, more patients and further follow up period are needed.

• Journal of Korean Neurosurgical Society
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• v.29 no.8
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• pp.1126-1135
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• 2000

Objectives : The goal of surgical management of cerebral arteriovenous malformation(AVM) is elimination of the lesion without development of new neurological deficits. To improve the management results of cerebral AVMs in the future, this article discusses about surgical complications of the AVM and their management. Material and Methods : During the past 18 years, 116 patients with cerebral AVMs were managed by surgery. Among these cases, 7 cases died, 7 cases developed new neurological deficits, 11 cases residual AVM and 5 cases intracerebral hematoma(ICH) after surgery. The author analyzes the causes of those complications and investigates the methods to minimized those complications based on the review of the literatures. Results : One stage removal of AVM and ICH in the poor neurological state were performed in 5 of 7 death cases. Subtotal removal of ICH followed by delayed AVM surgery after recovery is regard as one method to improve the outcome of patient with large ICH. Postoperative new neurological deficits developed owing to normal perfusion pressure breakthrough(NPPB) in 3, judgement error in 2, preoperative embolization in 1 and cortical injury in 1 case(s). Proper management of NPPB, accurate anatomical knowledge and physiological monitoring during operation, and well trained skill for embolization are regard as methods to minimize those complications. Residual AVMs after surgery were noticed in 11 cases, in which unintended 6 cases due to inaccurate dissection of peripheral margin of AVM, and intended 3 cases due to massive brain swelling during operation, 1 cases due to diffuse type and 1 case due to multiple type of AVM. Accurate dissection of peripheral margin of AVM and mild hypotension during operation may help to avoid this complication. Postoperative hemorrhage occurred in 3 cases due to rupture of the residual AVM and in 2 cases due to oozing from the AVM bed. Complete resection of AVM, complete control of bleeding points at AVM bed and mild hypotension during early postoperative period are the methods to avoid this complication. Conclusion : A precise but flexible therapeutic strategy and refined skill for endovascular, radiosurgical and microsurgical techniques are required to successful treatment of cerebral AVM. Adequate timing of AVM resection, accurate anatomical knowledge, proper management of NPPB and accurate dissection of peripheral margin of AVM are the key points for avoiding complications of the AVM surgery.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.158-163
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• 1999

The quality change of black rice during storage at $20^{\circ}C$ was measured to determine a packaging material for black rice storage, using polyethylene film (PE), polypropylene film (PP) and laminated film with PE and PP (PE/PP). Water activity of black rice was 0.642 at initial time and changed little in 8 months during storage at $20^{\circ}C$. Acidity of black rice was 25 mg KOH at initial time and was the lowest, 33.16 mg KOH, within PE/PP of 0.10 mm in thickness in 8 months during storage at $20^{\circ}C$. L, a and b values, hunter color value of black rice were not changed significantly in all packaging materials during 8 month storage. Hardness of the black rice was increased a little, but changed the smallest in PF/PP and the largest in PE with 0.05mm in thickness in 8 months. During storage, hexanal content was increased the smallest in PE/PP and the largest in 0.05 mm PE. Among fatty acid of black rice, linoleic acid was changed the smallest in PE/PP and the largest in 0.05 mm PE. In conclusion, PE/PP was better for the storage of black rice than PE and PP.