• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.342-347
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• 2009

Statement of problem: when using resin for class II restoration, micoleakage by instrumentation can be regarded as the primary negative characteristic. A review of the available literature suggests that using flowable resin as liner to decreased microleakage. Purpose: The aim of this study was to determine the influence of the nanofilled flowable resin lining on marginal microleakage after load cycling in class II composite restoration fillings using nanofiller resin. Material and methods: 24 extracted premolars were prepared with class II cavity. F group was restored the nanofilled resin with the nanofilled flowable resin as liner. NF group was restored the nanofilled resin only. After restoration, an experiment was performed on 2 groups using a 300N load at 104, 105 and 106 cycles. Prior to and before each load cycling, it was gauged length on total marginal microleakage, axial marginal microleakage and buccal, gingival, lingual marginal microleakage. Data were analyzed with the Mann-Whitney test & Kruskal-Wallis test. Results: There were statistically significant differences between 2 groups and between individual groups. (P <.05) The result showed less microleakage in teeth restored by the nanofilled resin, which was lined by the nanofilled flowable resin. Conclusion: There was significant reduction in microleakage when the nanofilled flowable resin lining was placed underneath the nanofilled resin in class II composite restoration fillings.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.374-379
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• 2010

Objectives: Nickel-titanium (Ni-Ti) rotary instruments have some unexpected disadvantages including the tendency to screw-in to the canal. The purpose of this study was to evaluate the influence of root canal curvatures on the screw-in effect of Ni-Ti rotary files. Materials and Methods: A total of 80 simulated root canals in clear resin blocks were used in the study. Canals with curvature of 0, 10, 20 and 30 degrees were instrumented with ProTaper instruments SX, S1, S2 and a ProFile of #25/0.06 to 1.0-2.0 mm beyond the initial point of root curvature. The screw-in force was measured with a specially designed device while canal was instrumented with a ProFile of #30/0.06 at a constant speed of 300 rpm. The data were subjected to one-way ANOVA and Scheffe multiple range test for post-hoc test. Results: Larger degree of canal curvature generated significantly lesser screw-in forces in all groups (p < 0.001). Conclusions: More attention needs to be paid when using rotary instruments in canals with less curvature than canals with more curvatures to prevent or reduce any accidental overinstrumentation.

• Journal of the Korean Orthopaedic Association
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• v.54 no.3
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• pp.211-218
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• 2019

Herniation of the intervertebral disc is a medical disease manifesting as a bulging out of the nucleus pulposus or annulus fibrosis beyond the normal position. Most lumbar disc herniation cases have a favorable natural course. On the other hand, surgical intervention is reserved for patients with severe neurological symptoms or signs, progressive neurological symptoms, cauda equina syndrome, and those who are non-responsive to conservative treatment. Numerous surgical methods have been introduced, ranging from conventional open, microscope assisted, tubular retractor assisted, and endoscopic surgery. Among them, microscopic discectomy is currently the standard method. Biportal endoscopic spinal surgery (BESS) has several merits over other surgical techniques, including separate and free handling of endoscopy and surgical instruments, wide view of the surgical field with small skin incisions, absence of the procedure of removing fog from the endoscope, and lower infection rate by continuous saline irrigation. In addition, existing arthroscopic instruments for the extremities and conventional spinal instruments can be used for this technique and surgery for recurred disc herniation is applicable because delicate surgical procedures are performed under a brightness of 2,700 to 6,700 lux and a magnification of 28 to 35 times. Therefore, due to such advantages, BESS is a novel technique for the surgical treatment of lumbar disc herniation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.174-180
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• 2001

The technology to efficiently manage computer communication network is in need as the computer communication network becomes more complicated and users want services more diversified. This has brought industries, research institutes and standadization organizations to consider an effective network management protocol. CMIP and the SNMP have considerable differences in structure and capacity Therefore, it is essential to have enables differences between network management protocol to gear for the two communication management system which is the most widely used and will be continuously used. In this thesis we suggest an interworking function Integrated Network Management for the Design of Proxy. According to the suggest algorithm, by using scoping, it stores the management information, so that it may pass the related information at the inner cash efficiently. Therefore, we can not only reduce some unnecessary management operation considerably but also bring some efficiency of saving the total management system response time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.73-79
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• 2012

Kiosks are widely used in drive-thru systems in parking lots or on the highway to provide various services to drivers. However, the driver must stop at an exact location to access the kiosk, since its panel is fixed. In order to improve the kiosk accessibility, in this study we developed a manipulator that can adjust the position of the kiosk panel. The number of active joints was minimized to lower the cost, whereas a parallelogram mechanism and passive joints were adopted to increase its convenience for the users. Furthermore, a safety mechanism using springs and a cam was designed to ensure the safety of the user in the case of an emergency. The performance of the position controller and the safety mechanism were verified through various tests. In addition, the proposed collision reaction strategy improved the safety performance of the kiosk system.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.5 no.1
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• pp.17-25
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• 2011

This paper aims to find the optimal control gain for enhancing the convenience of electric walking frames and design a control algorithm. With the recent advances in medical technology, there has been a rapid increase in the aging population and a variety of mobile walking frames have been developed for improvement of the quality of life. However, the manual walking frames of such mobile aids don't have any electric motor which helps facilitate elderly users' walking and thus are not efficient enough for the old people of weak strength to use especially when moving on uneven surfaces such as slopes or thresholds. The types of electric walking frames have been developed to overcome such inefficiency. Electric walking frames require users' control operations for motor driving unlike manual frames. Therefore, when they are not properly handled, it causes considerable inconvenience to their users. The present study compared the electric walking frames with manual ones in terms of operational convenience and attempted to improve the user convenience of walking frames varying the control value for user convenience based on certain standards. This paper presented a haptic sensor designed to recognize the will to walk and measure the degree of convenience and proposed a control algorithm for improvement of convenience. For user convenience, this paper evaluated the relative convenience of walking frames in view of changing differences between the center of vehicle (COV) and the center of position (COP). With the employment of an electric walking frame and a new measuring method, all the processes were experimentally tested and validated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.73-76
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• 2008

세계 해상 조난 및 안전제도(GMDSS)의 도입으로 해상에서의 조난통신 방식이 기존의 음성 전화에 의한 조난통신방식에서 디지털선택호출(DSC) 장치에 의한 조난통신 방식으로 변함에 따라 허위의 조난신호가 다량으로 발생하고 있다. 이러한 허위의 조난신호는 효율적인 수색구조에 막대한 영향을 미치고 있어 시급히 개선이 요구되고 있다. 이러한 문제점을 해결하기 위하여 국제해사기구에서는 허위 조난신호 경감을 위한 관련 결의서 및 권고안을 작성 유포하는 등 지난 10여 년 동안 많은 노력을 기울였으나 허위의 조난신호는 감소하고 있지 않다. 우리나라의 경우에도 구난무선국에 의해 접수된 조난신호 중 90% 이상이 허위 또는 미확인 신호로 판명되고 있어 심각한 상황을 나타내고 있다. 이러한 허위의 조난신호는 대부분 테스트 과정이나 사용자의 조작 실수에 의해 발신되는 것으로 나타나고 있다. 특히 디지털선택호출 장치에 의한 허위의 조난신호가 다량으로 발생함으로써 세계 해상 조난 및 안전제도의 정착에 많은 어려움을 야기하고 있다. 따라서 본 논문에서는 허위 조난신호 현황을 세부적으로 분석하고 허위의 조난신호가 다량으로 발생하고 있는 원인에 대하여 분석하였으며, 이러한 허위의 조난신호 경감을 위한 해결 방안을 제시하였다.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.189-192
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• 2000

The objective of this study was to investigate the effect of high content of light-absorbing pigments on overall photosynthetic efficiency in high density microalgal cultures. The light harvesting complex II (LHC II) regulating gene of Rhodobacter sphaeroides, photosynthetic purple bacterium, was removed to construct a mutant strain that had less pigment content. The mutant and wild type strains were cultured under various light intensity by adjusting the distance from the light source. The productivity of the mutant strain was higher at high light intensity (over 118 ${\mu}E/m^2/s$) compared with one of the wild type , and was lower at low light intensity (34 ${\mu}E/m^2/s$). Especially, the concentration of LHC II mutant strain was 56% higher at 118 ${\mu}E/m^2/s$. The reduction of per cell pigment contents in the mutant strain lessened the degree of the mutual shading and thus enhanced the overall photosynthetic efficiency.

• Journal of Chest Surgery
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• v.39 no.12 s.269
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• pp.931-933
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• 2006

Robotic assisted surgery in adult patient with congenital ventricular septal defect Since December in 2005, we have done minimally invasive surgeries in selected cases of mitral valve diseases, tricuspid valve diseases, atrial septal defects and atrial fibrillations with the $AESOP^{TM}$ robotic arm. We have had a better surgical view and skill, according to accumulation of the experience of this procedure. Recently, we performed robotic assisted surgery in a 47-year-old female with congenital perimembranous ventricular septal defect.

• Journal of The Korean Association For Science Education
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• v.9 no.2
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• pp.29-45
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• 1989

The purpose of this paper is to study the operational skills of apparatuses in observation and experiments a point of view of the teaching-learning guidance of the middle school science. In order to understand the actual condition of the field learner, the achivment levels of learner have been investigated on the operational skills of apparatuses, observation and experiments through 1120 students of 16 middle schools. The results showed that there were large differences at each item and especially, in animate natural part(physics and chemistry), the handling ability was very low to average 33 percentage. By the result of analyzing the actual condition of the experiment and field science from the question of 114 science teachers who work in 40 middle schools in P distriet. it has been recognized that though the lessons through the experiments stimulate the motivation of learning, it couldn't be mamaged efficently because of all the educational conditions. And it was revealed that the major part of Experiment was performed not by student who is subjective in the course of learning but by teacher through experiments.