• 대한치과의료관리학회지
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• 제7권1호
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• pp.10-20
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• 2019

Korean dental hygienists perform more tasks in dental clinics than are described in the law. The purpose of this study was to investigate the actual work of Korean dental hygienists in dental clinics using an observational study design. Two dental hygienists observed and recorded the work performed in 1 day from the time of commencement to the time of leaving work by 18 dental hygienists working in the dental clinic in a single area. Data management, prevention of infection, counseling, calculus removal, radiography, assistance of fixed orthodontic treatment, assistance of fixed prosthetic treatment, and preparation for implant surgery were recorded. Among the tasks that take more than 1 min, the most time-consuming tasks were document management, infection control, consultation, calculus removal, preparation for implant surgery, assistance of orthodontic treatment, and assistance of fixed prosthetic treatment. Korean dental hygienists are performing various tasks, such as infection control, dental hospital/clinic management, oral disease prevention, and dental treatment assistants.

• 대한치과보철학회지
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• 제43권6호
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• pp.717-726
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• 2005

Statement of problem. One of the common problems of provisional crown and fixed partial denture materials is that when they are subjected to constant loads for a long period of time, they exhibit a dimensional change (creep). Purpose. The aim of this study was to investigate the viscoelastic behaviour of polymer-based provisional crown and fixed partial denture materials with time at constant compressive load. Material and methods. Three dimethacrylate-based materials (Protemp 3 Garant, Temphase, Luxatemp) and one monomethacrylate-based material (Trim) were selected. Dimensional changes of the specimens were recorded by a LVDT to evaluate their viscoelastic behavior and creep strain. For all specimens, two loading procedures were used. At first, static compressive stress of 4 MPa was applied for 30 minutes and followed by 1 hour of strain recovery. Then, after 24 hours of water storage, the specimens were loaded again. The creep values between materials were statistically analyzed using one-way ANOVA and multiple comparison $Scheff\acute{e}$ test. Independent samples t-test was also used to identify the difference of creep strain between first and secondary loading conditions at the significance level of 0.05. Results. Following application of the first loading, Trim showed the highest maximum creep strain (32.7%) followed by Luxatemp, Protemp 3 Garant and Temphase, with values of 3.78%, 2.86% and 1.77%, respectively. Trim was significantly different from other materials (P<0.05), while there were no significant differences among Luxatemp, Protemp 3 Garant and Temphase (P>0.05). The highest recovery and permanent set of Trim, were significantly different from those of others (P<0.05). At the secondary loading of the dimethacrylate-based materials, creep deformation, recovery and permanent set decreased and the percentage of recovery increased, while in Trim, all values of the measurements increased. This result showed that the secondary loading at 24 hours produced a significant creep magnitude. Conclusion. The dimethacrylate-based provisional crown and fixed partial denture materials showed significantly higher creep resistance and lower deformation than the monomethacrylate-based material. Thus, monomethacrylate-based materials should not be used in long-term stress-bearing situations.

• 한국시뮬레이션학회논문지
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• 제27권3호
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• pp.117-129
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• 2018

이 논문에서는 철도차량 의장공장에서 적용되는 두 종류의 배치안 개념에 대한 논의하고자 한다. 현재 시스템은 전통적인 흐름라인 방식에 따라 조립라인이 설계되어 있지만 새로운 시스템은 고정위치형 배치방식을 따르고자 한다. 시스템에 영향을 주는 요소로는 공정시간의 변동성, 결품률 및 결품시간의 분포를 고려하였다. 시뮬레이션 실험결과 해당시스템의 경우 생산량, 차량당 평균 체류시간, 편성당 평균 체류시간 모두 고정위치형 배치방식을 사용하는 것이 좋다는 결론을 얻었다. 또한 시스템의 고정위치형 방식이 흐름라인 방식에 비해 변화에 둔감하게 반응함으로써 강건성 측면에서도 우수하다는 결론을 얻었다.

• The Journal of Advanced Prosthodontics
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• 제3권1호
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• pp.33-36
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• 2011

In process of fabrication of a fixed partial denture, dies are trimmed to expose margins of the preparations. The need for the soft tissue cast is quite evident as the soft tissue emergence profile that surrounds the prepared tooth is destroyed in the process of fabrication. This article describes a modified technique to fabricate the soft tissue cast for the conventional fixed partial denture. The impression made with the polyvinylsiloxane was first poured to prepare the die cast. After retrieval of the cast, the same impression was poured second time with the resin based resilient material to cover the facial and proximal gingival areas. The remaining portion of the impression was poured with the gypsum material. This technique does not require additional clinical appointment, second impression procedure, technique sensitive manipulations with impression, or cumbersome laboratory procedures. The simplicity of this technique facilitates and justifies its routine use in fabrication of the fixed partial denture.

• 산업공학
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• 제17권4호
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• pp.459-465
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• 2004

The purpose of this paper is to examine whether there are relationships of substitutability or complementarity between the call demand of fixed telecommunication and mobile telecommunication services. In order to clarify the relationships, we suggest a model of call demand of fixed telecommunication service which incorporates the variables representing the diffusion of mobile telecommunications subscription and estimate it with relevant time series data. Finally it is shown that there is complementary relationship between the call demand of fixed telecommunication and mobile paging services, and it is also found that there is substitutable relationship between the long distance call demand of fixed telecommunication and mobile phone services.

• Communications for Statistical Applications and Methods
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• 제11권2호
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• pp.213-225
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• 2004

A fixed-strike lookback option is an option whose payoff is determined by the maximum (or minimum) price of the underlying asset within the option's life. Under the Black-Scholes framework, the time-t price of an equity asset follows a geometric Brownian motion. Applying the method of Esscher transforms, this paper will derive explicit pricing formulas for fixed-strike lookback call and put options, respectively. In addition, this paper will show a relationship (duality property) between the pricing formulas of the call and put options. Finally, this paper will derive explicit pricing formulas for the fixed-strike lookback options when their underlying asset pays dividends continuously at a rate proportional to its price.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2093-2095
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• 2002

Nowadays, there are actually lots of changes in wireless communications of Korea. But it is not an exact PTP(Peer to Peer) Communication. In other words, a mobile station which can find fixed station can be connected with wireless internet server or other services, oppositely fixed station cannot approach to mobile station. Even though it exists, it is difficult to communicate with full duplex. We can service using CDMA 1X techniques such as cellular based SMS (Short Message Service) service or very simple MPRG Services. In this paper, we propose a system, using DirectX based mobile/fixed station stand alone program, depending on bandwidth of wireless service provider, tranceiving high resolution moving picture or reliable data regularly by a fixed connection each other.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.767-771
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• 2002

This paper proposes a multivariate $T^2$ variable interval control chart with sampling at fixed times, where samples are taken at specified equally spared fixed time points, and additional samples are allowed between these fixed times when indicated by the preceding $T^2$ statistics. At fixed sampling tunes, the $T^2$ statistics are composed of all quality characteristics, and a part of qualify characteristics are selected to obtain $T^2$ statistics at additional sampling times. A Markov chain approach is used to evaluate the performance of the proposed chart.

• 산업경영시스템학회지
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• 제34권2호
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• pp.1-8
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• 2011

This paper proposes a variable sampling interval multivariate $T^2$ control chart with sampling at fixed times, where samples are taken at specified equally spaced fixed time points and additional samples are allowed between these fixed times when indicated by the preceding $T^2$ statistics. At fixed sampling points, the $T^2$ statistics are composed of all quality characteristics and a part of quality characteristics are selected to obtain $T^2$ statistics at additional sampling points. A Markov chain approach is used to evaluate the performance of the proposed chart. Numerical studies for the performance of the proposed chart show that the proposed chart reduces the observations obtained from a process and detects the assignable cause of a process with low correlated quality characteristics quickly.

• 한국정밀공학회지
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• 제21권7호
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• pp.22-29
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• 2004

As a result of high integration of semiconductor device, the global planarization of multi-layer structures is necessary. So the chemical mechanical polishing(CMP) is widely applied to manufacturing the dielectric layer and metal line in the semiconductor device. CMP process is under influence of polisher, pad, slurry, and process itself, etc. In comparison with the general CMP which uses the slurry including abrasives, fixed abrasive pad takes advantage of planarity, resulting from decreasing pattern selectivity and defects such as dishing & erosion due to the reduction of abrasive concentration especially. This paper introduces the manufacturing technique of fixed abrasive pad using hydrophilic polymers with swelling characteristic in water and explains the self-conditioning phenomenon. And the tungsten CMP using fixed abrasive pad achieved the good conclusion in terms of the removal rate, non-uniformity, surface roughness, material selectivity, micro-scratch free contemporary with the pad life-time.