• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.6
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• pp.448-456
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• 2011

Introduction: Condylar fractures are common in the maxillofacial region, comprising 29-40 percent of all mandibular fractures, accounting for about 20-62 percent). Previous studies reported that pediatric condylar fractures can cause disorders in facial growth and function, and the treatment methods have been controversial. Recently, conservative treatment has shown good results in skeletal growth and functional recovery but the conservative treatment of pediatric condylar fractures has shown unpredictable and undesirable results in some cases, such as facial asymmetry and temporomandibular joint disorder. This study examined the specific age groups and specific mandibular condylar fracture type in growing children treated conservatively in the past. Materials and Methods: Eighteen patients (10 men and 8 women) who received conservative treatment for unilateral condylar fractures in Dankook University Dental Hospital between 2000 to 2007 were followed up for a mean period of 7.2 years. Results: In the survey of 18 pediatric patients who received conservative treatment for condylar fractures, the incidence of temporomandibular dysfunction and growth disturbance was 45% and 35%, respectively. Conclusion: In all complications, the symptoms observed most frequently was mouth opening displacement of the mandible exceeding 2 mm. The other complications of functional and growth disturbance included facial asymmetry concentrated along specific condylar types. Complications including facial asymmetry and functional and growth disturbances showed an increasing tendency according to the specific fracture types. Functional and growth disturbances in the undisplaced condylar fracture type showed a lower incidence(P <0.05). Functional and growth disturbances differed according to the fracture type, which has poor relationship with articular fossa and condyle(P <0.05). Functional and growth disturbance in the cases of the high-level condylar fracture type showed a higher incidence(P <0.05). The functional and growth disturbances of the fracture types were similar in the fragment-contact and non-contact groups(P >0.05).

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.183-190
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• 2020

This study was designed to investigate the current state of lens wearing and care, and to investigate eye discomfort according to the care method. Data of 209 female college students wearing lenses for more than 1 year were analyzed using the SPSS / WIN 22.0 program. 40.2% of female students wear lenses every day and 97.1% wear all day. However, only 45.4% of students washed it daily, and only 17.7 % used protein remover during wash, which resulted in poor management. 98.1% of students complained of discomfort due to the lens, and the Ocular Surface Index (OSDI) scored 42.88 ± 15.25, which was classified as a severe dry eye and threatened eye health. Therefore, it is necessary to improve students' awareness of lens management, and periodical lens inspection and management education are needed.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.247-252
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• 2017

Hydrophilic coating solutions were prepared by reacting a silane coupling agent, aminosilane with colloidal silica (15~20 nm in diameter). Hydrophilic coating films were also obtained by depositing the hydrophilic coating solutions on polycarbonate substrates by dip-coating and subsequently by thermal curing at $120^{\circ}C$. During this process, the effect of types of aminosilane was studied on the properties of coating films. As a result, coating films, prepared with 3-aminopropyltriethoxysilane (APTES) as aminosilane, showed contact angles of $25{\sim}44^{\circ}$ and a poor pencil hardness of B. On the other hand, coating films, prepared with 3-aminopropyltrimethoxysilane (APTMS) as aminosilane, exhibited contact angles of $26{\sim}37^{\circ}$ and a good pencil hardness of 2H.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5838-5842
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• 2011

The study mainly aims to explore how deterioration of motor control center, namely MCC, and vibration put impact on temperature of bus bar as well as temperature change of bolt-nut joint. The motor control center consists of three internal parts (i.e. R, S, T) which are for motor operation of high capacity. Two dimensional mechanism for measuring temperature was designed and manufactured with infrared temperature sensor. Installing it in inner motor control center enabled researcher to monitor temperature of bus bar as well as amount of change of current regularly. Temperature change of bus bar according to load was primarily examined based on a bolted joint in the experiment. It was clearly verified that temperature change of bus bar was proportional to current consumption. Therefore, installing non-contact two dimensional mechanism for measuring temperature in motor control center would be expected to prevent temperature rise owing to overload current and power outage as well as fire accident which can be triggered by poor electrical contact.

• Tunnel and Underground Space
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• v.20 no.6
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• pp.446-454
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• 2010

CAES-G/T (Compressed Air Energy Storage - Gas Turbine) power generation is a likely option for the buffer facility stabilizing the fluctuation of the renewable powers, such as wind and solar powers. Considering the geological conditions, the underground CAES facility is most probable if the CAES-G/T generation is planed in Korea. In this kind of facility, a concrete plug is installed to seal the compressed air in the container, so that the selection of the shape and dimension of concrete plug could be a critical design factor. The stability evaluation of two types of plug was carried out by investigating the distribution of the factor of safety in the plugs and the distribution of contact pressure over the contact surface. The analysis result shows that the taper-shaped plug is more structurally stable than the wedge-shaped plug for the given geological condition. Possible separation of the rock-concrete interface around the spring line of the wedge-shaped plug is anticipated, which means the possible leakage of compressed air through the side wall and also means the poor mobilization of frictional resistance on that area.

• Korean Journal of Metals and Materials
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• v.46 no.5
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• pp.289-295
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• 2008

The effect of the alloy elements(Si/Mn) ratio on the coating quality including wettabilty with molten zinc, galvannealing kinetics and crater has been investigated in interstitial-free high strength steel(IFHSS) containing Si and Mn. When the Si/Mn ratio was below 0.75, IF-HSS exhibited a good wettability leading to a good galvannealed coating quality after annealing at $800^{\circ}C$ for 40s in $15%H_2-N_2$ mixed gas with dew point $-60^{\circ}C$. In contrast, the wettability and galvannealed coating quality were deteriorated in the Si/ Mn ratio above 0.75. It is shown that they have relevance to oxides forms by selective oxidation on the steel surface. The oxide particles dispersed on the steel surface with a surface coverage of below 40% resulted in good wettability and galvannealed coating quality. The oxide particle is mainly consisted of $Mn_2SiO_4$ with low contact angle in molten zinc. On the other hand, the continuous oxide layer on the steel surface, such as network- and film-type,caused to poor wettability and galvannealed coating quality. The coverage of oxide layer was above 80%, and its chemical species was $SiO_2$ with high contact angle in molten zinc. Consequently, the Si/Mn alloy ratio played an importance role in galvannealed coating quality of IF-HSS.

• Economic and Environmental Geology
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• v.19 no.1
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• pp.1-18
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• 1986

A group of 16 $Zn+Pb{\pm}Ag$ deposits distributed in the Pyeongchang-Jucheon area, Kangwon-do, South Korea, were semi-regionally investigated. These deposits are contact metasomatic and/or hydrothermal replacement types hosted in the carbonate-dominated Cambrian Machari Formation and Ordovician Ibtanri Formation, and also in the carbonate interbeds of the Precambrian argillic metasediments. Comparing some key aspects of the individual deposits, it is found that the ore deposits hosted in the Machari and Ibtanri Formations are mostly of steeply-dipping chimneys with or without skarn minerals and are rich in Ag and Pb>Zn in metal grade whereas those occuring in the carbonate interbeds of the Precambrian argillic metasediments are gently-dipping conformable lenticular orebodies mostly with skarn minerals and are generally poor in Ag and Zn>Pb. The skarn mineralization in the area appears to have occurred during the lower Cretaceous (118.7Ma) to mid-Cretaceous (107.8Ma) time assumed from the K-Ar dates of the Dowon and Pyeongchang granites which are closely associated with the skarn ore deposits. The Rb/Ba/Sr ratios of these granites indicate that they are of strongly differentiated anomalous granites, and the Nb vs. Y and Rb vs. Y+Nb plots fall on the field of volcanic arc setting. The contact aureoles are zoned, giving the sequence in order of increasing distance from igneous contact: garnet-wollastonite, granet-wollastonite-clinopyroxene and garnet-clinopyroxene in such as the Pyeongchang and Yeonwol 114 areas. Electron microprobe analyses reveal that garnets and clinopyroxenes are generally low in Fe and Mn. Garnets are grossular to intermediate grandite except for those from the Ogryong exoskarn which are richer in andradite, pyrope and spessartine fractions. This indicates that the oxidation state of skarn-forming environment at Ogryong was higher than at the other deposits. Clinopyroxenes are mostly salitic except for those from the Ogryong exoskarn which involve considerable amounts of hedenbergite and johansenite fractions. The ${\delta}^{18}O$ value of Jurassic biotite granite at Ogryong is higher (+10.21‰) than that of Cretaceous one at Chodun (+8.41‰). The ${\delta}^{13}C$ values of carbonate rocks range from -0.89‰ to 0.68‰ and the ${\delta}^{18}O$ values range from +11.91‰ to + 19.34‰ indicating that these carbonate rocks are of marine origin. However, the ${\delta}^{13}C$ values of skarn calcite and vein calcite are -4.80‰ and -12.92‰, and the ${\delta}^{18}O$ values are +5.56‰ and +10.32‰, respectively, indicating that these calcites are of hydrothermal origin. The ${\delta}^{34}S$ values of sulfide minerals range from +4.4‰ to +8.7‰ suggesting that the sulfurs are of magmatic origin.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.362-374
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• 2007

Statement of problem. The intial stability for osseointegration of implant has been an interesting factor. Especially, in the case of poor bone quality or immediately loaded implant, various strategies have been developed focusing on the surface of materials to improve implant fixation to bone. The microscopic properties of implant surfaces play a major role in the osseous healing of dental implants. Purpose. The aims of this study are to perform a histologic and histomorphometric comparison of the healing characteristics of three different surfaces and the comparison of resonance frequency analysis (RFA) values measured by $Osstell^{TM}$ and perio-test values (PTV) measured by Periotest. Material and methods. A total of 24 screw titanium implants (Dentium Co., Seoul, Korea) with 6mm in length and 3.4mm in diameter, were placed in the mandible of 4 beagle dogs. Implants were divided into three groups following the surface treatment methods: Group I is machined(control group). Group II is anodically oxidized. Group III is coated 500nm in thickness with hydroxyapatite(HA) by ion beam assisted deposition(IBAD) on the anodized oxidization. Bone blocks from 2 dogs were caught after 3 weeks of covered healing and another blocks from 2 dogs after 6 weeks. RFA values and PTV were measured right after insertion and at 3 and 6weeks. Histomorphometric analysis was made with Kappa Image Base System to calculate bone-to-implant contact (BIC) and bone area inside the threads. Pearson's correlation analyses were performed to evaluate the correlation between RFA and PTV, BIC and bone area ratio of three different surfaces at 3 and 6 weeks. Results. 1) In all surface treatment methods, the RFA values decreased and the PTV values increased until 6 weeks in comparison to initial values. 2) At 3 weeks, no significant difference was found from bone-to-implant contact ratio and bone area ratio of three different surface treatment methods(P>0.05). However, at 6 weeks, different surface treatment methods showed significantly different bone-toimplant contact ratio and bone area ratio(P<0.05). 3) In the implants with the IBAD on the anodic oxidization, significant difference was found between the 3 weeks and the 6 weeks bone area ratio(P<0.05). 4) Correlation was found between the RFA values and the bone area ratio at 3 and 6 weeks with significant difference(P<0.05). Conclusions. These results indicate that the implants with the IBAD on the anodic oxidization may have a high influence on the initial stability of implant.

• Journal of Korea Entertainment Industry Association
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• v.15 no.1
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• pp.191-197
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• 2021

This study studied the effect of visual difference on balance and walking ability in college students' life care. The study was conducted on 45 students attending H University in G City, divided into control groups (n=22, not wearing glasses and contact lenses) and experimental groups (n=23, wearing glasses and contact lenses). In not wearing glasses and contact lenses, the subjects measured visual acuity with logMAR charts, evaluated their balance ability with BIOrescue, and evaluated walking ability with G-Walk. The results of this study showed that the experimental group had statistically significantly lower vision than the control group in the visual acuity measurement(p<.01). Static balance ability was statistically significant increase in center of mass movement of the right foot in the experimental group compared to the control group(p<.05). Dynamic balance ability was statistically significantly reduce in limit of stability for groups of experiments compared to control group(p<.05). The walking ability was statistically significantly shorter on step length and stride length, swing of the experimental group compared to the control group in the right foot(p<.05). The findings showed that the visual difference in university students reduces balance and walking ability. Therefore, university students with poor visual acuity are recommended to correct of visual acuity to prevent collision and falls in their daily lives.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1655-1657
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• 2004

The electrical fire frequently happens through carelessness of a vinyl and rubber cords such as a poor contact, a mechanical stress and so on. Electrical fire occupies the greater part(about 30%) of all fires in Korea. In this paper, we compared to the fire dispersive patterns of vinyl and rubber cords according to the external flame in the wall-model. The fire progress and dispersive patterns were measured by a high speed imaging system(HG-100K, REDLAKE, USA). From the results, short-circuit of the vinyl cords are easy to happen than the rubber cords by the external flame. The pattern of fire was progressed a flashover, scattering and disconnection. The fire progress on the vinyl cord is not observed because the ignition energy decreases. However, the fire was progressed continuously on the rubber cord.