• The Journal of Advanced Prosthodontics
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• 제6권2호
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• pp.88-95
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• 2014

PURPOSE. The purpose of this study is to evaluate if pre-treatment with desensitizers have a negative effect on microtensile bond strength before cementing a restoration using recently introduced self-adhesive resin cement to dentin. MATERIALS AND METHODS. Thirty-five human molars' occlusal surfaces were ground to expose dentin; and were randomly grouped as (n=5); 1) Gluma-(Glutaraldehyde/HEMA) 2) Aqua-Prep F-(Fluoride), 3) Bisblock-(Oxalate), 4) Cervitec Plus-(Clorhexidine), 5) Smart protect-(Triclosan), 6) Nd:YAG laser, 7) No treatment (control). After applying the selected agent, RelyX U200 self-adhesive resin cement was used to bond composite resin blocks to dentin. All groups were subjected to thermocycling for 1000 cycles between $5-55^{\circ}C$. Each bonded specimen was sectioned to microbars ($6mm{\times}1mm{\times}1mm$) (n=20). Specimens were submitted to microtensile bond strength test at a crosshead speed of 0.5 mm/min. Kolmogorov-Smirnov, Levene's test, Kruskal-Wallis One-way Analysis of Variance, and Conover's nonparametric statistical analysis were used (P<.05). RESULTS. Gluma, Smart Protect and Nd:YAG laser treatments showed comparable microtensile bond strengths compared with the control group (P>.05). The microtensile bond strengths of Aqua-Prep F, and Cervitec Plus were similar to each other but significantly lower than the control group (P<.05). Bisblock showed the lowest microtensile bond strength among all groups (P<.001). Most groups showed adhesive failure. CONCLUSION. Within the limitation of this study, it is not recommended to use Aqua-prep F, Cervitec Plus and Bisblock on dentin when used with a self-adhesive resin cement due to the decrease they cause in bond strength. Beside, pre-treatment of dentin with Gluma, Smart protect, and Nd:YAG laser do not have a negative effect.

• 대한치과보철학회지
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• 제46권3호
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• pp.298-306
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• 2008

STATEMENT OF PROBLEM: Effect of surface treatment of ceramic under loading does not appear to have been investigated. PURPOSE: The aim of this study was to investigate the effect of surface treatment of esthetic ceramic, which is performed to increase the bonding strength, on the fracture stress under controlled cyclic loading condition. MATERIAL AND METHODS: Sixty 1.0 mm-thick specimens were made from Mark II Vitablocs (Vita Zahnfabrik, Germany) and divided into 3 groups: polished (control), sandblasted, and etched. Specimens of each group were bonded to a dentin analog material base including micro-channels to facilitate the flow of water to the bonding interface. Bonded ceramics were cyclically loaded with a flat-end piston in the water (500,000 cycles, 15Hz). Following completion of cyclic loading, specimens were examined for subsurface crack formation and subsequent stress was determined and loaded to next specimen by the staircase method according to the crack existence. RESULTS: There were significant differences of mean fatigue limit in the sandblasted (222.86 ${\pm}$ 23.42 N) and etched group (222.86 ${\pm}$ 14.16 N) when compared to polished group (251.43 ${\pm}$ 10.6 N) (P<.05; Wald-type pair-wise comparison and post hoc Bonferroni test). Of cracked specimens, surface treated group showed longer crack propagation after 24 hours. All failures originated from the radial cracking without cone crack. Fracture resistance of this study was very low and comparable to failure load in the oral cavity. CONCLUSION: Well controlled cyclic loading could induce clinically relevant cracks and fracture resistance of Mark II ceramic was relatively low applicable only to anterior restorations. Surface treatment of inner surface of feldspathic porcelain in the matsicatory area could influence lifetime of restorations.

• 유통과학연구
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• 제13권2호
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• pp.63-73
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• 2015

Purpose - Satisfaction with service is evaluated according to customers' subjective judgment. The expected value of customer service and its evaluations depend on the customers' position. The customer recognizes two different forms of service levels. One is satisfaction and the other is dissatisfaction. Customers who are satisfied want to receive the service in future. However, those dissatisfied try to change the service. The service provider tries to improve the service. There are two different service cycles. One is the successful cycle and the other is the failure cycle. This study aimed to empirically determine the effects of the justice and authenticity of service recovery on customer behavioral intention through an integrated approach to cognitive justice and psychological authenticity. Research design, data, and methodology - Based on a literature review, justice of service recovery was categorized into three types: distributive, procedural, and interactive. Then, authenticity was added to obtain four independent variables, along with recovery satisfaction as a parameter. Behavioral intention, as an outcome variable, was divided into the repurchase intention and positive word-of-mouth. The model and hypotheses were created and measurement items were developed. A questionnaire survey of items concerning the service recovery experience at family restaurants was conducted on college students and residents in Gwangju from September 30 to October 31, 2013. A total of 400 copies of the questionnaire were sent out and 385 were returned. Respondents answered questions about the importance of, and satisfaction with service recovery on a 5-point Likert scale. Excluding 174 copies without service failure experiences and 7 inappropriate copies, 204 copies were analyzed using SPSS 21.0 for Windows and AMOS 20.0 to determine the reliability and validity of measurements. The hypotheses were tested through a goodness-of-fit analysis. Results - First, distributive justice positively affected recovery satisfaction. Second, procedural and interactive justice had no impact. Third, authenticity positively affected recovery satisfaction. Fourth, distributive justice had relatively stronger effects on recovery satisfaction than authenticity. Fifth, recovery satisfaction significantly affected repurchase intention and positive word-of-mouth and it proved effective in mediation. Finally, additional analysis was performed for descriptive statistics of the principal variables by various demographic characteristics and significant differences were found in gender, occupation, and so on. Conclusions - This study has academic significance as the fairness and authenticity of service recovery were investigated to reveal the effects on behavior. The findings could be applied to a wide range of service recovery strategies. However, there are some limitations. First, data was collected only from the residents of Gwangju and most respondents were aged 20-30. Future studies should target a wide range of areas and age groups. Second, because the questionnaire used in this study targets only convenience family restaurants, the results of this study cannot be generalized to all services companies. Future research should be done on a wide range of industries such as hotels, airlines, and hospitals, and perform a comparison between sectors.

• Clinical and Experimental Pediatrics
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• 제55권2호
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• pp.42-47
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• 2012

$Mycoplasma$ $pneumoniae$ (MP), the smallest self-replicating biological system, is a common cause of upper and lower respiratory tract infections, leading to a wide range of pulmonary and extra-pulmonary manifestations. MP pneumonia has been reported in 10 to 40% of cases of community-acquired pneumonia and shows an even higher proportion during epidemics. MP infection is endemic in larger communities of the world with cyclic epidemics every 3 to 7 years. In Korea, 3 to 4-year cycles have been observed from the mid-1980s to present. Although a variety of serologic assays and polymerase chain reaction (PCR) techniques are available for the diagnosis of MP infections, early diagnosis of MP pneumonia is limited by the lack of immunoglobulin (Ig) M antibodies and variable PCR results in the early stages of the infection. Thus, short-term paired IgM serologic tests may be mandatory for an early and definitive diagnosis. MP infection is usually a mild and self-limiting disease without specific treatment, and if needed, macrolides are generally used as a first-choice drug for children. Recently, macrolide-resistant MP strains have been reported worldwide. However, there are few reports of apparent treatment failure, such as progression of pneumonia to acute respiratory distress syndrome despite macrolide treatment. The immunopathogenesis of MP pneumonia is believed to be a hyperimmune reaction of the host to the insults from MP infection, including cytokine overproduction and immune cell activation (T cells). In this context, immunomodulatory treatment (corticosteroids or/and intravenous Ig), in addition to antibiotic treatment, might be considered for patients with severe infection.

• 마이크로전자및패키징학회지
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• 제12권1호
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• pp.65-71
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• 2005

At present, Electronic industries push ahead to eliminate the Pb(Lead) -a hazardous material-from all products. Especially, we have performed to select the optimum standard composition of lead free alloy for the application to products for about 3 years from 2000. These days, we have the chance for applying to the mass-production. This project constructed the system for applying the lead free solders on consumer electronic products, which is one of the major products of the LG Electronics. To select the lead free solders with corresponding to the product features, we have passed through the test and applied with Sn-3.0Ag-0.5Cu alloy system to our products, and for the application to the high melting temperature composition, we secured the thermal resistance of the many parts and substrate and optimized the processing conditions. We have operated the temperature cycling test and the high temperature storage test under the standards to confirm the reliability of the products. On these samples, we considered the consequence of our decision by the operating test. For the long life time of the product, we have operated the temperature cycling test at $-45^{\circ}C\;-\;+125^{\circ}C$, 1 cycle/hour, 1000 cycles. Also we have tested the tin whisker growth about lead free plating on lead finish. We have analyzed with the SEM, EDS and any other equipment for confirming the failure mode at the joint and the tin whisker growth on lead free finish.

• 산업경영시스템학회지
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• 제43권4호
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• pp.41-47
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• 2020

As modern industries are highly being developed, it is required that mechanical parts have to be manufactured with a high precision. In order to have precise parts, error-free designs have to be done before manufacturing with accuracy. For this intention being fulfilled, a mechanical analysis is essential for design proof. Nowadays, FEM simulation is a popular tool for verifying a machine design. In this paper, an impeller, being utilized in a compressor or an oil mixer as an actuator, is studied for an evaluation. The purpose of this study is to present a safety of an impeller for a proof of its mechanical stability. A static analysis for stress, strain, and deformation within a regular usage is examined. This simulation test shows 357.26×106 Pa for maximum equivalent stress and 0.207mm for total deformation. A fatigue test is carried to provide durability and its result shows that minimum safety factor is 3.2889, which guarantees that it runs without a fatigue failure in 106 cycles. The natural frequencies for the impeller is ranged from 228.09Hz to 1,253.6Hz for the 1st to the 6th mode. Total deformations at these natural frequencies are shown from 6.84mm to 12.631mm. Furthermore, Campbell diagram reveals that a critical speed is not found throughout regular rotational speeds. From the test results for the analysis, this paper concludes that the suggested impeller is proved for its mechanical safety and good to utilize at industries.

• Radiation Oncology Journal
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• 제26권4호
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• pp.195-203
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• 2008

목 적: 절제 불가능한 식도암에서의 근치적 동시항암화학방사선치료의 치료 성적과 재발 양상에 대해 알아보고자하였다. 대상 및 방법: 1994년 2월부터 2002년 12월까지 서울아산병원에서 절제불가능한 국소진행된 식도암으로 진단 받거나 내과적으로 수술이 불가능한 식도암으로 진단 받은 후 근치적 목적의 동시항암화학방사선치료를 시행 받은 168명을 대상으로 하였다. 방사선치료는 원발병소와 종격동, 그리고 원발병소와 림프절 전이의 위치에 따라 쇄골상부림프절과 복강림프절을 포함하여 $42{\sim}46\;Gy$의 외부방사선을 조사하였고, 이후 원발병소와 림프절 전이 부위에는 $54{\sim}66\;Gy$까지 추가 조사하였다. 분할조사 방법은 분할조사선량 $1.8{\sim}2\;Gy$씩 1일 1회 조사하거나, 1.2 Gy씩 1일 2회 조사하였다. 고선량률관내 방사선치료를 실시하는 경우에는 Ir-192를 이용한 고선량률 방식으로 3 Gy씩 $3{\sim}4$회 시행하였다. 항암치료는 5-FU와 cisplatin을 이용하여 동시항암화학방사선치료(5-FU $1,00\;mg/m^2$/day, days $2{\sim}6$, $30{\sim}34$, cispiatin $60\;mg/m^2$/day, days 1, 29)를 2주기 시행하고 방사선치료 후에 2 주기를 추가하여 시행하였다. 결 과: 분석 가능한 환자는 160명 이었으며, 추적관찰 기간은 1개월에서 149개월(중앙값 10개월)이었다. 환자의 AJCC 병기는 I, II, III, IV 기가 각각 5명(3.1%), 38명(23.8%), 68명(42.5%), 49명(30.6%)이었다. 26명(16.3%)의 환자에서는 $9{\sim}12\;Gy$의 추가 관내방사선치료를 시행하였다. 관내방사선치료를 포함하여 총 40 Gy 이상 조사받은 144명의 환자에서 외부 방사선조사량의 범위는 $44.4{\sim}66\;Gy$ (중앙값 59.4)이었고, 총 방사선 조사량의 범위는 $44.4{\sim}72\;Gy$ (중앙값 60)이었다. 분석가능한 160명의 환자 중에서 101명(63.1%)에서 재발하였으며, 재발 양상으로는 국소 재발이 20명(12.5%), 지속적 병변 또는 국소 진행이 61명(38.1%), 원격전이가 15명(9.4%), 국소재발과 원격전이가 함께 있는 경우가 5명(3.)%)이었다. 전체환자의 중앙생존기간은 11.1개월이었고, 2년 및 5년 전체생존율은 각각 31.8%, 14.2%이었다. 중앙무병 생존기간은 10.4개월이었고, 2년 및 5년 무병생존율은 각각 29.0%, 22.7%이었다. 항암화학방사선치료 후에 종양 반응 및 림프절 병기만이 전체생존율에 유의하게 영향을 미치는 예후인자였다. 방사선 조사량(${\geq}50$ Gy vs. < 50 Gy), 관내 방사선치료의 추가 유무, 분할조사(1회/day vs. 2회/day)에 따른 전체 생존율 및 무병생존율에 유의한 차이는 관찰되지 않았다. 결 론: 식도암에서 근치적 동시 항암화학방사선치료의 성적은 다른 연구 결과와 유사한 결과를 보였다. 동시 항암화학 방사선치료 후의 주된 재발 양상은 국소 재발이었다. 방사선 조사량의 증가(${\geq}50\;Gy$), 고선량률관내방사선치료 및 과분할조사법의 시행은 치료 성적을 향상시키지 못하였다.

• 한국의학물리학회지:의학물리
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• 제28권4호
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• pp.156-163
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• 2017

To verify the usefulness of a steam sterilizer equipped with an electronic Bowie-Dick test system, this study was carried out using two methods, utilizing both a steam sterilizer and an electronic Bowie-Dick tester. The first method is to confirm the error detection of the chemical Bowie-Dick test pack and the electronic Bowie-Dick tester in a malfunctioning sterilizer environment. For this purpose, the Bowie-Dick test program for the steam sterilizer was used to test three types of test packs commonly used in hospitals and the electronic Bowie-Dick tester by changing the set values of temperature, time, and vacuum frequency. The second is an experiment to check the sterilizer's normal operation with the electronic Bowie-Dick tester and the usefulness of grasping the cause of the malfunction. The results showed that the sterilization temperature was the same as that of the test pack at a temperature $1{\sim}6^{\circ}C$ lower than the reference temperature of $134^{\circ}C$. In the test with the sterilization exposure time as a variable, there was a normal discoloration at a time difference of 30~90 s. In the experiment using the number of vacuum cycles, the test was correct by performing the normal discoloration only at the normal condition of 3 times. The test results of 30 hospitals were 100 failure tests by a total of 291 Bowie-Dick tests. Of these, the failure factors related to an internal temperature that the chemical test packs could not detect were the greatest, and the four factors related to temperature, including the internal temperature, were found to be 71.18% of total malfunctions. In addition, the Bowie-Dick tester was provided within 30 min after the start of the Bowie-Dick test to confirm the performance of the sterilizer and the detailed cause. A steam sterilizer equipped with an electronic Bowie-Dick test system is used to manage individual sterilizers. In the current steam sterilizer with many temperature-related errors, it is possible to check the malfunction of the temperature difference that the test pack cannot detect, and the cause of error for the sterilizer is immediately detected after the test. The steam sterilizer equipped with the electronic Bowie-Dick test system assists with infection control with accurate sterilizer performance assurance.

• 대한치과보철학회지
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• 제47권1호
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• pp.46-52
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• 2009

연구목적: 최근 임플란트 상부보철물의 주재료로서 티타늄의 수요가 증가하고 있고, 급속도로 발전하고 있는 CAD/CAM (computer - aided design/computer-aided manufacturing) 기술이 접목되어 티타늄을 절삭하여 제작하는 방법이 주목을 받고 있으며 치과 임상에서 점점 그 영역이 넓어지고 있다. 다만, 하나의 티타늄괴를 절삭하여 만드는 방법의 특성상 기계적 유지력을 얻을 수 있는 비드 등을 형성할 수 없고, 통상적인 재료인 금 합금이나 도재용 합금 주조체에 비해 도재와의 결합력도 떨어지는 것이 보완해야 할 점으로 지적되고 있다. 이에 본 연구는 절삭형 티타늄을 이용한 보철물 제작에 많이 사용되고 있는 열중합 의치상 레진, 간접 복합 레진, 도재와 Grade II 순수 티타늄 사이의 결합 강도를 비교 평가해 보고자 하였다. 연구 재료 및 방법: 지름 9 mm, 높이 10 mm의 Grade II 순수 티타늄 원통형 시편 37개를 3군으로 나누어 각각 직경 7 mm, 높이 1 mm의 열중합 의치상 레진 (Lucitone 199, DENTSPLY Trubyte, York, USA), 간접 복합 레진 (Sinfony, 3M ESPE, Seefeld, Germany), 도재 (Triceram, Dentaurum, Ispringen, Germany)와 결합시켰다. 시편은 $5-55^{\circ}C$에서 1000회 열순환 처리 후, 범용 시험기 (Instron, Universal Testing Machine, Model 4465, USA)를 이용하여 1 mm/min의 속도로 하중을 가하여 전단결합강도를 측정하였다. 파절된 단면의 양상을 관찰하고 각 군별 파절양상을 조사하였다. 측정값은 one-way ANOVA와 Scheffe's multiple range test (${\alpha}=0.05$)로 분석하였다. 결과: 열중합 의치상 레진인 Lucitone 199 ($17.82{\pm}5.13\;MPa$)의 결합 강도가 가장 높았으며, 도재인 Triceram ($12.97{\pm}2.11\;MPa$), 복합레진인 Sinfony ($6.00{\pm}1.31\;MPa$) 순으로 감소하였다. Lucitone 199와 Sinfony 군의 파절 양상은 대부분이 부착성 파절인 데에 반해 Triceram 군에서는 복합성 파절이 많았다. 결론: CAD/CAM을 이용한 절삭형 티타늄 구조물 상방에 전장용 심미 재료로는 열중합형 의치상 레진이 가장 강한 결합 강도를 보인다. 기존의 주조체의 유지구 등에서 얻는 강도에 비해 약하고, 부착성 파절이 많은 점 등은 향후 이들 재료와 티타늄간의 결합력을 높이기 위한 보다 많은 연구가 이루어져야 할 것을 시사한다.

• Structural Engineering and Mechanics
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• 제47권4호
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• pp.575-598
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• 2013

The study presents the results of an experimental program concerning the shear force transfer between reinforced concrete (RC) jackets and existing columns with damages. In order to investigate the effectiveness of the repair method applied and the contribution of each shear transfer mechanism of the interface. It includes 22 concrete columns (core) (of 24,37MPa concrete strength) with square section (150mm side, 500 mm height and scale 1:2). Ten columns had initial construction damages and twelve were subjected to initial axial load. Sixteen columns have full jacketing at all four faces with 80mm thickness (of 31,7MPa concrete strength) and contain longitudinal bars (of 500MPa nominal strength) and closed stirrups spaced at 25mm, 50mm or 100mm (of 220MPa nominal strength). Fourteen of them contain dowels at the interface between old and new concrete. All columns were subjected to repeated (pseudo-seismic) axial compression with increasing deformation cycles up to failure with or without jacketing. Two load patterns were selected to examine the difference of the behavior of columns. The effects of the initial damages, of the reinforcement of the interface (dowels) and of the confinement generated by the stirrups are investigated through axial- deformation (slip) diagrams and the energy absorbed diagrams. The results indicate that the initial damages affect the total behavior of the column and the capacity of the interface to shear mechanisms and to slip: a) the maximum bearing load of old column is decreased affecting at the same time the loading capacity of the jacketed element, b) suitable repair of initially damaged specimens increases the capacity of the jacketed column to transfer load through the interface.