Present tooth bonding system can be categorized into total etching bonding system (TE) and self-etching boding system (SE) based on their way of smear layer treatment. The purposes of this study were to compare the effectiveness between these two systems and to evaluate the effect of number of themocycling on microleakage of class V composite resin restorations. Total forty class V cavities were prepared on the single-rooted bovine teeth and were randomly divided into four experimental groups: two kinds of bonding system and another two kinds of thermocycling groups. Half of the cavities were filed with Z250 following the use of TE system, Single Bond and another twenty cavities were filled with Metafil and AQ Bond, SE system. All composite restoratives were cured using light curing unit (XL2500, 3M ESPE, St. Paul, MN, USA) for 40 seconds with a light intensity of $600mW/cm^2$. Teeth were stored in distilled water for one day at room temperature and were finished and polished with Sof-Lex system. Half of teeth were thermocycled 500 times and the other half were thermocycled 5,000 times between $5^{\circ}C$ and $55^{\circ}C$ for 30 second at each temperature. Teeth were isolated with two layers of nail varnish except the restoration surface and 1 mm surrounding margins. Electrical conductivity (${\mu}A$) was recorded in distilled water by electrochemical method. Microleakage scores were compared and analyzed using two-way ANOVA at 95% level. From this study, following results were obtained: There was no interaction between variables of bonding system and number of thermocycling (p = 0.485). Microleakage was not affected by the number of thermocycling either (p = 0.814). However, Composite restoration of Metafil and AQ Bond, SE bond system showed less microleakage than composite restoration of Z250 and Single Bond, TE bond system (p = 0.005).
Journal of the korean academy of Pediatric Dentistry
/
v.26
no.2
/
pp.365-376
/
1999
The importance of finishing and polishing the restoration has been described by several authors. The final step provides for improved metallurgical properties, better marginal adaptation, reduced plaque accumulation. Unfortunately, finishing of the restorations can produce damage from temperature rises at the pulpal wall. The aim of this study was to determine the changes in temperature can be occurred during the use of finishing and polishing instruments under a variety of conditions. ; with or without a water coolant, intermittent or continuous operation, high or low rotation speed, remaining dentin thickness and various restorative materials. Class V preparations were cut on extracted molars and restored with composite resin(Z 100), resin-modified glass ionomer cements(Dyract, Fuji II LC), and amalgam. Finishing was done with aluminum oxide coated disc($Sof-lex^{(R)}$ polishing disc, 3M, USA). The following results were obtained. 1. The rise of temperature during polishing of amalgam restorations was the highest among the all experimental groups except polishing with water coolant(P<0.05). However, there were no statistical differences in temperature rises between Z 100, Dyract and Fuji II LC(P>0.05). 2. The intrapulpal temperature was greatly influenced by the applied time, and intermittent polishing was showed significantly lower temperature rises than continuous polishing(P<0.01). 3. The intrapulpal temperature was increased according to the application of polishing regard less of using water coolant. However, polishing with water coolant showed significantly lower temperature in the pulp than not used water coolant(P<0.01).
Kim Munjo;Im Jeongyeon;Kang Sanggil;Kim Munchrul;Kang Kyungok
Journal of Broadcast Engineering
/
v.10
no.1
s.26
/
pp.43-56
/
2005
In the existing broadcasting environment, it is not easy to serve the bi-directional service between a broadcasting server and a TV audience. In the uni-directional broadcasting environments, almost TV programs are scheduled depending on the viewers' popular watching time, and the advertisement contents in these TV programs are mainly arranged by the popularity and the ages of the audience. The audiences make an effort to sort and select their favorite programs. However, the advertisement programs which support the TV program the audience want are not served to the appropriate audiences efficiently. This randomly provided advertisement contents can occur to the audiences' indifference and avoidance. In this paper, we propose the target advertisement service for the appropriate distribution of the advertisement contents. The proposed target advertisement service estimates the audience's profile without any issuing the private information and provides the target-advertised contents by using his/her estimated profile. For the experimental results, we used the real audiences' TV usage history such as the ages, fonder and time of the programs from AC Neilson Korea. And we show the accuracy of the proposed target advertisement service algorithm. NDS (Normalized Distance Sum) and the Vector correlation method, and implementation of our target advertisement service system.
The purpose of this study was to evaluate the influence of sodium ascorbate on microtensile bond strengths of total-etching adhesive system to pulp chamber dentin treated with NaOCl. Pulp chambers of extracted human non-caries permanent molars were treated as follows: group 1, with 0.9% NaCl; group 2, with 5.25% NaOCl; group 3, with 5.25% NaOCl and 10% sodium ascorbate for 1min; group 4, with 5.25% NaOCl and 10% sodium ascorbate for 1 min and 10ml of water; group 5, with 5.25% NaOCl and 10% sodium ascorbate for 5 min; group 6, with 5.25% NaOCl and 10% sodium ascorbate for 5 min and 10ml of water; group 7, with 5.25% NaOCl and 10% sodium ascorbate for 10 min; group 8, with 5.25% NaOCl and 10% sodium ascorbate for 10 min and 10ml of water. Treated specimens were dried, bonded with a total-etching adhesive system (Single bond), restored with a composite resin(Z250) and kept for 24h at 100% humidity to measure the microtensile bond strength. NaOCl-treated group (group 2) demonstrated significantly lower strength than the other groups. No significant difference in microtensile bond strengths was found between NaCl-treated group (group 1) and sodium ascorbatetreated groups (group 3-8). The results of this study indicated that dentin treated with NaOCl reduced the microtensile bond strength of Single bond. Application of 10% sodium ascorbate restored the bond strength of Single bond on NaOCl-treated dentin. Application time of sodium ascorbate did not have a significant effect.
It is known that $MgAl_2O_4$ has higher resistance to moisture than MgO, in humid ambient MgO is chemically unstable. It reacts very easily with moisture in the air. In this study, the characteristic of $MgAl_2O_4$ and $MgAl_2O_4/MgO$ layers as dielectric protection layers for AC- PDP (Plasma Display Panel) have been investigated and analysed in comparison for conventional MgO layers. MgO and $MgAl_2O_4$ films both with a thickness of $1000\AA$ and $MgAl_2O_4/MgO$ film with a thickness of $200/800\AA$ were grown on the Cu substrates using the electron beam evaporation. $1000\AA$ thick aluminium layers were deposited on the protective layers in order to avoid the charging effect of $Ga^+$ ion beam while the focused ion beam(FIB) is being used. We obtained sputtering yieds for the MgO, $MgAl_2O_4$ and $MgAl_2O_4/MgO$ films using the FIB system. $MgAl_2O_4/MgO$ protective layers have been found th show $24{\sim}30%$ lower sputtering yield values from 0.244 up to 0.357 than MgO layers with the values from 0.364 up to 0.449 for irradiated $Ga^+$ ion beam with energies ranged from 10 kV to 14 kV. And $MgAl_2O_4$ layers have been found to show lowest sputtering yield values from 0.88 up to 0.109. Secondary electron emission coefficient(g) using the ${\gamma}$- FIB. $MgAl_2O_4/MgO$ and MgO have been found to have similar g values from 0.09 up to 0.12 for indicated $Ne^+$ ion with energies ranged from 50 V to 200 V. Observed images for the surfaces of MgO and $MgAl_2O_4/MgO$ protective layers, after discharge degradation process for 72 hours by SEM and AFM. It is found that $MgAl_2O_4/MgO$ protective layer has superior hardness and degradation resistance properties to MgO protective layer.
Journal of the korean academy of Pediatric Dentistry
/
v.31
no.1
/
pp.66-78
/
2004
The objective of this study was to apply the vibration technique to reduce the viscosity of bonding adhesives and thereby compare the bond strength and resin penetration in enamel and dentin achieved with those gained using the conventional technique and vibration technique. For enamel specimens, thirty teeth were sectioned mesio-distally. Sectioned two parts were assigned to same adhesive system but different treatment(vibration vs. non-vibration). Each specimen was embedded in 1-inch inner diameter PVC pipe with a acrylic resin. The buccal and lingual surfaces were placed so that the tooth and the embedding medium were at the same level. The samples were subsequently polished silicon carbide abrasive papers. Each adhesive system was applied according to its manufacture's instruction. Vibration groups were additionally vibrated for 15 seconds before curing. For dentin specimen, except removing the coronal part and placing occlusal surface at the mold level, the remaining procedures were same as enamel specimen. Resin composite(Z250. 3M. U.S.A.) was condensed on to the prepared surface in two increments using a mold kit(Ultradent Inc., U.S.A.). Each increments was light cured for 40 seconds. After 24 hours in tap water at room temperature, the specimens were thermocycled for 1000cycles. Shear bond strengths were measured with a universal testing machine(Instron 4465, England). To investigate infiltration patterns of adhesive materials, the surface of specimens was examined with scanning electron microscope. The results were as follows: 1. In enamel the mean values of shear bond strengths in vibration groups(group 2, 4, 6) were greater than those of non-vibration group(group 1, 3, 5). The differences were statistically significant except AQ bond group. 2. In dentin, the mean values of shear bond strengths in vibration groups(group 2, 4, 6) were greater than those of non-vibration groups(group 1, 3, 5). But the differences were not statistically significant except One-Up Bond F group. 3. The vibration group showed more mineral loss in enamel and longer resin tag and greater number of lateral branches in dentin under SEM examination.
Lee Dae-Hwan;Choi Young-Min;Cho Soo-Churl;Lee Jung-Ho;Shin Min-Sup;Lee Dong-Woo;Kim Bong-Seog;Kim Boong-Nyun
Journal of the Korean Academy of Child and Adolescent Psychiatry
/
v.17
no.1
/
pp.10-18
/
2006
Objective : The aims of this study were to explore the relations of internet addiction to depression, impulsivity, and obsessive-compulsivity in adolescents. Methods : 1410 high school students (male=611, female=799 : mean age=$16.2{\pm}0.7$) were included in this study. The questionnaire consisted of items on demographic characteristics and internet use pattern. We assessed the level of internet addiction using Young's internet addiction scale (IAS) Barratt impulsiveness scale (BIS) and Maudsley obsessive compulsive inventory (MOCI) were also self-rated. In this study, We defined upper 25% of IAS as 'addiction group' and lower 25% as 'non-addiction group'. Results : The results were as follows ; 1) Male students had significantly higher mean scores on Internet addiction scale than females and there was significantly higher rate of male students in addiction group. 2) The addiction group spent more time for internet use, especially for games than non-addiction group. 3) The addiction group showed significantly higher total scores on BDI, BIS, and MOCI than non-addiction group. 4) Significant associations have been found between the level of internet addiction and depression, impulsivity, and obsessive-compulsivity, respectively. Conclusion : Depression, impulsivity, and obsessive-compulsivity could be significant factors predicting internet addiction. Especially, direct effect of impulsivity could be the most significant to explain internet addiction. Adolescents with high impulsivity may be vulnerable to internet addiction.
In this paper, we propose the development of embedded board for integrated radiation exposure protection fireman's life-saving alarm capable of location tracking and radiation measurement. The proposed techniques consist of signal processing unit, communication unit, power unit, main control unit. Signal processing units apply shielding design, noise reduction technology and electromagnetic wave subtraction technology. The communication unit is designed to communicate using the wifi method. In the main control unit, power consumption is reduced to a minimum, and a high performance system is formed through small, high density and low heat generation. The proposed techniques are equipment operated by exposure to poor conditions, such as disaster and fire sites, so they are designed and manufactured for external appearance considering waterproof and thermal endurance. The proposed techniques were tested by an authorized testing agency to determine the effectiveness of embedded board. The waterproof grade has achieved the IP67 rating, which can maintain stable performance even when flooded with water at the disaster site due to the nature of the fireman's equipment. The operating temperature was measured in the range of -10℃ to 50℃ to cope with a wide range of environmental changes at the disaster site. The battery life was measured to be available 144 hours after a single charge to cope with emergency disasters such as a collapse accident. The maximum communication distance, including the PCB, was measured to operate at 54.2 meters, a range wider than the existing 50 meters, at a straight line with the command-and-control vehicle in the event of a disaster. Therefore, the effectiveness of embedded board for embedded board for integrated radiation exposure protection fireman's life-saving alarm has been demonstrated.
Journal of the korean academy of Pediatric Dentistry
/
v.30
no.1
/
pp.102-109
/
2003
The purpose of this study was to evaluate the linear polymerization shrinkage(%) and microhardness of composite resin(Z-100, 3M, USA) according to 2-step light curing method. Conventional light curing unit(Curing Light 2500, 3M USA) and 2-step light curing unit(Elipar Highlight, ESPE, Germany) were used as light source. The strain gauge method was used for determination of polymerization shrinkage(%). Samples were divided by 3 groups according to light curing methods (Group I : $450mW/cm^2$, 40sec, Group II : $650mW/cm^2$, 40sec, Group III : $150mW/cm^2$, 10sec & $650mW/cm^2$, 30sec). Preparations of acrylic molds were followed by filling and curing. Strain gauges attached to each sample were connected to a strainmeter. Measurements were recorded at each second for the total of 10 minutes including the periods of light application. And microhardness of each group after 24hours from light irradiation were measured. Obtained data were analyzed statistically using Ore-way ANOVA and/or Scheffe test. The results of the present study can be summarized as follows: 1. Composite resin in acrylic molds showed the initial expansion at the early phase of polymerization. This was followed by the contraction with the rapid increase in volume during the first 60 seconds and gradually diminished as curing process continued. 2. The lowest linear polymerization shrinkage(%) was found in group III followed by group I, II during the measuring periods. 3. Group III using 2-step curing method showed statistically significant reduction of linear polymerization shrinkage(%) compared with group I, II at 1 minute and 10 minutes from light irradiation(p<0.05). 4. The microhardness values of each group not revealed significant difference.
Journal of the korean academy of Pediatric Dentistry
/
v.44
no.3
/
pp.335-340
/
2017
Composite resin becomes an essential material in pediatric dentistry. However, incremental filling of composite resin to minimize the polymerization shrinkage takes time. To reduce the polymerization shrinkage, clinicians and researchers have focused on bulk-filling materials. Bulk-base composite resin is newly introduced as bulk-filling composite resin. The purpose of this study was to evaluate microhardness profile of bulk-base composite resin according to the depth of cure. A high flow bulk-base material and a low flow bulk-base material were used for experimental group, and a conventional composite resin was used for control group. Each group consist of 20 specimens, $3.5{\times}3.5{\times}5.0mm$ mold was used to make specimen. Specimens were sectioned at the 2 mm and the 3 mm depth with milling machine. Microhardness profile was measured at the surface, 2 mm depth, 3 mm depth, and 4 mm depth. Microhardness of control group showed statistically significant difference (p < 0.05) according to the polymerization depth. In contrast, experimental group showed no statistically significant difference, except between 0 mm and 4 mm at HFB, 0 mm and 2 mm, 0 mm and 3 mm at MFB. At the surface and the 2 mm depth, the control group showed higher microhardness than the experimental groups (p < 0.05). However, at the 4 mm depth, the experimental groups showed significantly higher microhardness (p < 0.05). The results from this study, the bulk-base composite resin showed higher microhardness at the 4 mm and lower microhardness at the surface and the 2 mm depth. Therefore, if bulk-base resin overcomes the mechanical weakness, it could be considered using in pediatric dentistry.
본 웹사이트에 게시된 이메일 주소가 전자우편 수집 프로그램이나
그 밖의 기술적 장치를 이용하여 무단으로 수집되는 것을 거부하며,
이를 위반시 정보통신망법에 의해 형사 처벌됨을 유념하시기 바랍니다.
[게시일 2004년 10월 1일]
이용약관
제 1 장 총칙
제 1 조 (목적)
이 이용약관은 KoreaScience 홈페이지(이하 “당 사이트”)에서 제공하는 인터넷 서비스(이하 '서비스')의 가입조건 및 이용에 관한 제반 사항과 기타 필요한 사항을 구체적으로 규정함을 목적으로 합니다.
제 2 조 (용어의 정의)
① "이용자"라 함은 당 사이트에 접속하여 이 약관에 따라 당 사이트가 제공하는 서비스를 받는 회원 및 비회원을
말합니다.
② "회원"이라 함은 서비스를 이용하기 위하여 당 사이트에 개인정보를 제공하여 아이디(ID)와 비밀번호를 부여
받은 자를 말합니다.
③ "회원 아이디(ID)"라 함은 회원의 식별 및 서비스 이용을 위하여 자신이 선정한 문자 및 숫자의 조합을
말합니다.
④ "비밀번호(패스워드)"라 함은 회원이 자신의 비밀보호를 위하여 선정한 문자 및 숫자의 조합을 말합니다.
제 3 조 (이용약관의 효력 및 변경)
① 이 약관은 당 사이트에 게시하거나 기타의 방법으로 회원에게 공지함으로써 효력이 발생합니다.
② 당 사이트는 이 약관을 개정할 경우에 적용일자 및 개정사유를 명시하여 현행 약관과 함께 당 사이트의
초기화면에 그 적용일자 7일 이전부터 적용일자 전일까지 공지합니다. 다만, 회원에게 불리하게 약관내용을
변경하는 경우에는 최소한 30일 이상의 사전 유예기간을 두고 공지합니다. 이 경우 당 사이트는 개정 전
내용과 개정 후 내용을 명확하게 비교하여 이용자가 알기 쉽도록 표시합니다.
제 4 조(약관 외 준칙)
① 이 약관은 당 사이트가 제공하는 서비스에 관한 이용안내와 함께 적용됩니다.
② 이 약관에 명시되지 아니한 사항은 관계법령의 규정이 적용됩니다.
제 2 장 이용계약의 체결
제 5 조 (이용계약의 성립 등)
① 이용계약은 이용고객이 당 사이트가 정한 약관에 「동의합니다」를 선택하고, 당 사이트가 정한
온라인신청양식을 작성하여 서비스 이용을 신청한 후, 당 사이트가 이를 승낙함으로써 성립합니다.
② 제1항의 승낙은 당 사이트가 제공하는 과학기술정보검색, 맞춤정보, 서지정보 등 다른 서비스의 이용승낙을
포함합니다.
제 6 조 (회원가입)
서비스를 이용하고자 하는 고객은 당 사이트에서 정한 회원가입양식에 개인정보를 기재하여 가입을 하여야 합니다.
제 7 조 (개인정보의 보호 및 사용)
당 사이트는 관계법령이 정하는 바에 따라 회원 등록정보를 포함한 회원의 개인정보를 보호하기 위해 노력합니다. 회원 개인정보의 보호 및 사용에 대해서는 관련법령 및 당 사이트의 개인정보 보호정책이 적용됩니다.
제 8 조 (이용 신청의 승낙과 제한)
① 당 사이트는 제6조의 규정에 의한 이용신청고객에 대하여 서비스 이용을 승낙합니다.
② 당 사이트는 아래사항에 해당하는 경우에 대해서 승낙하지 아니 합니다.
- 이용계약 신청서의 내용을 허위로 기재한 경우
- 기타 규정한 제반사항을 위반하며 신청하는 경우
제 9 조 (회원 ID 부여 및 변경 등)
① 당 사이트는 이용고객에 대하여 약관에 정하는 바에 따라 자신이 선정한 회원 ID를 부여합니다.
② 회원 ID는 원칙적으로 변경이 불가하며 부득이한 사유로 인하여 변경 하고자 하는 경우에는 해당 ID를
해지하고 재가입해야 합니다.
③ 기타 회원 개인정보 관리 및 변경 등에 관한 사항은 서비스별 안내에 정하는 바에 의합니다.
제 3 장 계약 당사자의 의무
제 10 조 (KISTI의 의무)
① 당 사이트는 이용고객이 희망한 서비스 제공 개시일에 특별한 사정이 없는 한 서비스를 이용할 수 있도록
하여야 합니다.
② 당 사이트는 개인정보 보호를 위해 보안시스템을 구축하며 개인정보 보호정책을 공시하고 준수합니다.
③ 당 사이트는 회원으로부터 제기되는 의견이나 불만이 정당하다고 객관적으로 인정될 경우에는 적절한 절차를
거쳐 즉시 처리하여야 합니다. 다만, 즉시 처리가 곤란한 경우는 회원에게 그 사유와 처리일정을 통보하여야
합니다.
제 11 조 (회원의 의무)
① 이용자는 회원가입 신청 또는 회원정보 변경 시 실명으로 모든 사항을 사실에 근거하여 작성하여야 하며,
허위 또는 타인의 정보를 등록할 경우 일체의 권리를 주장할 수 없습니다.
② 당 사이트가 관계법령 및 개인정보 보호정책에 의거하여 그 책임을 지는 경우를 제외하고 회원에게 부여된
ID의 비밀번호 관리소홀, 부정사용에 의하여 발생하는 모든 결과에 대한 책임은 회원에게 있습니다.
③ 회원은 당 사이트 및 제 3자의 지적 재산권을 침해해서는 안 됩니다.
제 4 장 서비스의 이용
제 12 조 (서비스 이용 시간)
① 서비스 이용은 당 사이트의 업무상 또는 기술상 특별한 지장이 없는 한 연중무휴, 1일 24시간 운영을
원칙으로 합니다. 단, 당 사이트는 시스템 정기점검, 증설 및 교체를 위해 당 사이트가 정한 날이나 시간에
서비스를 일시 중단할 수 있으며, 예정되어 있는 작업으로 인한 서비스 일시중단은 당 사이트 홈페이지를
통해 사전에 공지합니다.
② 당 사이트는 서비스를 특정범위로 분할하여 각 범위별로 이용가능시간을 별도로 지정할 수 있습니다. 다만
이 경우 그 내용을 공지합니다.
제 13 조 (홈페이지 저작권)
① NDSL에서 제공하는 모든 저작물의 저작권은 원저작자에게 있으며, KISTI는 복제/배포/전송권을 확보하고
있습니다.
② NDSL에서 제공하는 콘텐츠를 상업적 및 기타 영리목적으로 복제/배포/전송할 경우 사전에 KISTI의 허락을
받아야 합니다.
③ NDSL에서 제공하는 콘텐츠를 보도, 비평, 교육, 연구 등을 위하여 정당한 범위 안에서 공정한 관행에
합치되게 인용할 수 있습니다.
④ NDSL에서 제공하는 콘텐츠를 무단 복제, 전송, 배포 기타 저작권법에 위반되는 방법으로 이용할 경우
저작권법 제136조에 따라 5년 이하의 징역 또는 5천만 원 이하의 벌금에 처해질 수 있습니다.
제 14 조 (유료서비스)
① 당 사이트 및 협력기관이 정한 유료서비스(원문복사 등)는 별도로 정해진 바에 따르며, 변경사항은 시행 전에
당 사이트 홈페이지를 통하여 회원에게 공지합니다.
② 유료서비스를 이용하려는 회원은 정해진 요금체계에 따라 요금을 납부해야 합니다.
제 5 장 계약 해지 및 이용 제한
제 15 조 (계약 해지)
회원이 이용계약을 해지하고자 하는 때에는 [가입해지] 메뉴를 이용해 직접 해지해야 합니다.
제 16 조 (서비스 이용제한)
① 당 사이트는 회원이 서비스 이용내용에 있어서 본 약관 제 11조 내용을 위반하거나, 다음 각 호에 해당하는
경우 서비스 이용을 제한할 수 있습니다.
- 2년 이상 서비스를 이용한 적이 없는 경우
- 기타 정상적인 서비스 운영에 방해가 될 경우
② 상기 이용제한 규정에 따라 서비스를 이용하는 회원에게 서비스 이용에 대하여 별도 공지 없이 서비스 이용의
일시정지, 이용계약 해지 할 수 있습니다.
제 17 조 (전자우편주소 수집 금지)
회원은 전자우편주소 추출기 등을 이용하여 전자우편주소를 수집 또는 제3자에게 제공할 수 없습니다.
제 6 장 손해배상 및 기타사항
제 18 조 (손해배상)
당 사이트는 무료로 제공되는 서비스와 관련하여 회원에게 어떠한 손해가 발생하더라도 당 사이트가 고의 또는 과실로 인한 손해발생을 제외하고는 이에 대하여 책임을 부담하지 아니합니다.
제 19 조 (관할 법원)
서비스 이용으로 발생한 분쟁에 대해 소송이 제기되는 경우 민사 소송법상의 관할 법원에 제기합니다.
[부 칙]
1. (시행일) 이 약관은 2016년 9월 5일부터 적용되며, 종전 약관은 본 약관으로 대체되며, 개정된 약관의 적용일 이전 가입자도 개정된 약관의 적용을 받습니다.