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THE EFFECT OF SMEAR LAYER TREATMENT ON THE MICROLEAKAGE (Smear layer 처리에 따른 미세누출에 대한 연구)

  • Lee, Jung-Min;Park, Sang-Hyuk;Choi, Gi-Woon
    • Restorative Dentistry and Endodontics
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    • v.31 no.5
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    • pp.378-389
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    • 2006
  • The purpose of this study was to compare the sealing ability of root canal obturation with or without the treatment of smear layer. Eighty extracted human teeth with one canal were selected Instrumentation was performed with crown-down technique. After instrumentation, root canals of the NaOCl group and NaOCl-6 group were irrigated with 3% NaOCl. EDTA group and EDTA-6 group were irrigated with 17% EDTA. Then all teeth were obturated using continuous wane obturation technique NaOCl group and EDTA group were immersed in methylene blue solution for 84hours. NaOCl-6 group and EDTA-6 group were immersed in methylene blue solution for 6months. The teeth were sectioned at 1.5 mn (Level 1), 3.0 mm (Level 2) and 4.5 mm (Level 3) from the root apex. The length of dye-penetrated inter-face and the circumferential length of canal at each level were measured using Sigma-Scan Pro 5.0. 1. The mean leakage ratio was decreased cervically. 2. NaOCl group showed higher mean leakage ratio than EDTA group at each level. But there was significant difference at level 1 only (p < 0.05). 3. NaOCl-6 group showed higher mean leakage ratio than EDTA-6 group at each level. But there was significant difference at level 1 only (p < 0.05). 4. NaOCl-6 group showed higher mean leakage ratio than NaOCl group at each level. But there was significant difference at level 1 only (p < 0.05). 5. EDTA-6 group showed higher mean leakage ratio than EDTA group at each level. But there was no significant difference. 6. In NaOCl group and NaOCl-6 group, scanning electron micrographs of tooth sections generally covered with smear layer. In EDTA group and EDTA-6 group, tooth sections showing the penetration of sealers to opened dentinal tubules. The results suggest that removal of smear layer was effective to reduce the apical microleakage of the root canal.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Screw Joint Stability under Cyclic Loading of Zirconia Implant Abutments (지르코늄 임플란트 지대주의 나사결합부 안정성에 관한 연구)

  • Lee, Mi-Soon;Suh, Kyu-Won;Ryu, Jae-Jun
    • The Journal of Korean Academy of Prosthodontics
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    • v.47 no.2
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    • pp.164-173
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    • 2009
  • Purpose: The purpose of this study was to evaluate the effect of abutment material on screw-loosening before and after cyclic loading. Among the different materials of abutments, zirconia and metal abutment were used. Material and methods: Two types of implant systems: external butt joint(US II, Osstem Implant, Korea) and internal conical joint(GS II, Osstem Implant, Korea) were used. In each type, specimens were divided into two different kinds of abutments: zirconia and metal(n=5). The implant was rigidly held in a special holding to device ensure fixation. Abutment was connected to 30 Ncm with digital torque gauge, and was retightened in 30 Ncm after 10 minutes. The initial removal torque values were measured. The same specimens were tightened in 30 Ncm again and held in the cycling loading simulator(Instron, USA) according to ISO/FPIS 1480. Cycling loading tests were performed at loads 10 to 250 N, for 1 million cycles, at 14 Hz,(by subjecting sinusoidal wave from 10 to 250 N at a frequency of 14 Hz for 1 million cycles,) and then postload removal torque values were evaluated. Results: 1. In all samples, the removal values of abutment screw were lower than tightening torque values(30 Ncm), but the phenomenon of the screw loosening was not observed. 2. In both of the implant systems, initial and postload removal torque of zirconia abutment were significantly higher than those of metal abutment(P<.05). 3. In both of the implant systems, the difference in removal torque ratio between zirconia abutment and metal abutment was not significant(P>.05). 4. In metal abutments, the removal torque ratio of GS II system(internal conical joint system) was lower than that of US II system(external butt joint system)(P<.05). 5. In zirconia abutments, the difference in removal torque ratio between the two implant systems was not significant(P>.05). Conclusion: Zirconia abutment had a good screw joint stability in the condition of one million cycling loading.

A Study on the Waveform Analysis of Left KWAN Pulse Dignosis by the Pressure (단계별(段階別) 가압(加壓)에 따른 좌관부위(左關部位) 맥파(脈波) 변화(變化))

  • Kim, Gyeong-Cheol;Lee, Jeong-Won;Ryu, Kyeong-Ho;Kim, Jong-Hwan;Park, Ju-Yeon
    • The Journal of the Society of Korean Medicine Diagnostics
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    • v.13 no.1
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    • pp.19-35
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    • 2009
  • Objectives : In the study on the waveform analysis of radial artery pulse diagnosis, we need to establish fundamentals of contemporary pulse diagnosis research. To achieve certain experimental basis on traditional pulse diagnosis, we have to research the differences of pulse waveform according to pressure (in 5 level) and position (Chon, Gwan, Cheok in radial artery). As a first step, in present thesis, we tried to find the differences of pulse waveform according to pressure. Methods and Results : In this research, we analyzed seven parameters of the waveform at five levels of pressure. The parameters are E(so called 'energy', a representative of pulse strength), h1(height of percussion wave) and h2(height of subincisura). The results were as follows. 1. When we analyzed the change of the waveform according to pressure in the left Gwan, E, hl, h2 and A differed between 1st and 2nd grade, between 1st and 3rd grade, between 1st and 4th grade, between 1st and 5th grade, between 2nd and 3rd grade, between 2nd and 5th grade, between 3rd and 5th grade and between 4th and 5th grade in 95% confidence interval. 2. And t2, t4 differed between 1st and 2nd grade, between 1st and 5th grade, between 2nd and 4th grade, between 2nd and 4th grade, between 2nd and 5th grade, between 3rd and 4th grade, between 3rd and 5th grade and between 4th and 5th grade in 95% confidence interval. 3. W differed between 1st and 3rd grade, between 1st and 4th grade, between 2nd and 3rd grade, between 2nd and 4th grade, between 2nd and 5th grade, between 3rd and 4th grade, between 3rd and 5th grade, and between 4th and 5th grade in 95% confidence interval. 4. And h2/h1 differed between 1st and 4th grade, between 1st and 5th grade, between 2nd and 4th grade, between 2nd and 5th grade, between 3rd and 4th grade & between 3rd and 5th grade in 95% confidence interval. 5. There were differences between 1st and 2nd grade & between 2nd and 5th grade in the case of t4/t2 in 95% confidence interval. And there were differences between 1st and 5th grade, between 3rd and 4th grade, between 3rd and 5th grade & between 4th and 5th grade in the case of W/A in 95% confidence interval. And were differences between 1st and 2nd grade, between 2nd and 3rd grade, between 2nd and 4th grade, between 3rd and 4th grade, between 3rd and 5th grade & between 4th and 5th grade in the case of A/E in 95% confidence interval. Conclusions : As mentioned above, we conclude that the waveform analysis according to five grade pressure in the left Gwan shows the difference of waveform in each grade pressure.

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Evaluation of retrievability using a new soft resin based root canal filling material (레진 계통의 근관 충전재의 제거 용이성에 대한 평가)

  • Shin Su-Jung;Lee Yoon;Park Jeong-Won
    • Restorative Dentistry and Endodontics
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    • v.31 no.4
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    • pp.323-329
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    • 2006
  • The aim of this study was to evaluate the retrievability of Resilon as a root canal filling material Twenty-seven human single-rooted extracted teeth were instrumented utilizing a crown down technique with Gates-Glidden burs and ProFile system. In group1 (n = 12) canals were obturated with gutta percha and AH-26 plus sealer using a continuous wave technique and backfilled. In group 2 (n = 15) Resilon was used as a filling material. Then teeth were sealed and kept in $37^{\circ}C$ and 100% humidity for 7 days. For retreatment, the samples were re-accessed and filling material was removed using Gates-Glidden burs and ProFiles. Teeth were sectioned longitudinally to compare the general cleanliness and amount of debris $({\times}\;75)$ using SEM. Chi-square test was used $({\alpha}\;=\;0.05)$ to analyze the data. The total time required for removal of filling materials was expressed as mean ${\pm}SD$ (min) and analyzed by the Student t-test $({\alpha}\;=\;0.05)$, Required time for retreatment was $3.25\;{\pm}\;0.32$ minutes for gutta percha/ AH 26 plus sealer and $3.05\;{\pm}\;0.34$ minutes for Resilon. There was no statistically significant difference between the two experimental groups. There was no significant difference between the groups in the cleanliness of the root canal wall. This study showed that Resilon was effectively removed by Gates-Glidden burs and ProFiles.

Transient Abnormalities on Magnetic Resonance Imaging after Absence Seizures (결신발작 이후 확인된 일시적인 자기공명영상 이상 1예)

  • Yoo, Hye Won;Yoon, Lira;Kim, Hye Young;Kwak, Min Jung;Park, Kyung Hee;Bae, Mi Hye;Lee, Yunjin;Nam, Sang Ook;Kim, Young Mi
    • Journal of the Korean Child Neurology Society
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    • v.26 no.4
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    • pp.280-283
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    • 2018
  • Magnetic resonance imaging (MRI) is recommended for patients with epileptic seizures to rule out an underlying focal lesion. However, abnormalities in idiopathic generalized epilepsy, including childhood absence epilepsy, cannot usually be identified using brain imaging modalities such as MRI. Peri-ictal MRI abnormalities have been most commonly reported secondary to status epilepticus and are rarely observed in patients with focal seizures and generalized tonic-clonic seizures. Transient peri-ictal MRI abnormalities in absence epilepsy are extremely rare. A five-year-old girl presented with a three-day history of absence seizures that persisted despite continued treatment with sodium valproate. Electroencephalography showed bursts of generalized 3-Hz spike-and-wave discharges, during and after hyperventilation. Abnormal cortex thickening in the left perisylvian region was detected on T2-weighted brain MRI, and cortical dysplasia or a tumor was suspected. The patient started treatment with lamotrigine and was seizure-free after one month. The abnormal MRI lesion was completely resolved at the two-month follow-up. We report on a patient with childhood absence epilepsy and reversible brain MRI abnormalities in the perisylvian region. To our knowledge, this is the first report of transient MRI abnormalities after absence seizures. Transient peri-ictal MRI abnormalities should be considered for differential diagnosis in patients with absence seizures and a focal abnormality on brain MRI.

A Case Study of Strong Wind Event over Yeongdong Region on March 18-20, 2020 (2020년 3월 18일-20일 영동지역 강풍 사례 연구)

  • Ahn, Bo-Yeong;Kim, Yoo-Jun;Kim, Baek-Jo;Lee, Yong-Hee
    • Journal of the Korean earth science society
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    • v.42 no.5
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    • pp.479-495
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    • 2021
  • This study investigates the synoptic (patterns of southern highs, northern lows, and lows rapidly developed by tropopause folding), thermodynamic, and kinematic characteristics of a strong wind that occurred in the Yeongdong region of South Korea on March 18-20, 2020. To do so, we analyzed data from an automatic weather station (AWS), weather charts, the European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis, rawinsonde, and windprofiler radars. The daily maximum instantaneous wind speed, exceeding 20 m s-1, was observed at five weather stations during the analysis period. The strongest instantaneous wind speed (27.7 m s-1) appeared in the Daegwallyeong area. According to the analysis of weather charts, along with the arrangement of the north-south low-pressure line, the isobars were moved to the Yeongdong area. It showed a sine wave shape, and a strong wind developed owing to the strong pressure gradient. On March 19, in the northern part of the Korean Peninsula, with a drop in atmospheric pressure of 19 hPa or more within one day, a continuous strong wind was developed by the synoptic structure of the developing polar low. In the adiabatic chart observed in Bukgangneung, the altitude of the inversion layer was located at an altitude of approximately 1-3 km above the mountaintop, along with the maximum wind speed. We confirmed that this is consistent with the results of the vertical wind field analysis of the rawinsonde and windprofiler data. In particular, based on the thermodynamic and kinematic vertical analyses, we suggest that strong winds due to the vertical gradient of potential temperature in the lower layer and the development of potential vorticity due to tropopause folding play a significant role in the occurrence of strong winds in the Yeongdong region.

Influence of Detailed Structure and Curvature of Woven Fabric on the Luminescence Effect of Wearable Optical Fiber Fabric (직물의 세부 구조 및 굴곡이 웨어러블 광섬유의 발광 효과에 미치는 영향)

  • Yang, Jin-Hee;Cho, Hyun-Seung;Kwak, Hwy-Kuen;Oh, Yun-Jung;Lee, Joo-Hyeon
    • Science of Emotion and Sensibility
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    • v.21 no.4
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    • pp.55-62
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    • 2018
  • The two main requirements of wearable optical fiber fabrics are that they must presuppose a high degree of flexibility and they must maintain the luminance effect in both flat and bent conformations. Therefore, woven optical fiber fabrics that satisfy the above conditions were developed by both weaving and by using computer embroidery. First, we measured the brightness of the wearable optical fiber fabric in the flat state at a total of 10 measurement points at intervals of 1 cm. Second, the wearable optical fiber fabric was placed horizontally on the forearm, where three-dimensional bending occurs, and the luminance values were recorded at the same 10 measurement points. For the woven fabric in the flat state, the maximum, minimum, average, and standard deviation luminance values were $5.23cd/m^2$, $2.74cd/m^2$, $3.56cd/m^2$, and $1.11cd/m^2$, respectively. The corresponding luminance values from the bent forearm were $7.92cd/m^2$ (maximum), $2.37cd/m^2$ (minimum), $4.42cd/m^2$ (average), and $2.16cd/m^2$ (standard deviation). In the case of the computer-embroidered fabric, the maximum, minimum, average, and standard deviation luminance values in the flat state were $7.56cd/m^2$, $3.84cd/m^2$, $5.13cd/m^2$, and $1.04cd/m^2$, respectively, and in the bent forearm state were $9.6cd/m^2$, $3.63cd/m^2$, $6.13cd/m^2$, and $2.26cd/m^2$, respectively. Therefore, the computer-embroidered fabric exhibited a higher luminous effect than the woven fabric because the detailed structure reduced light-loss due to the backside fabric. In both types of wearable optical fiber fabric the luminance at the forearm was 124% and 119%, respectively, and the light emitting effect of the optical fiber fabric was maintained even when bent by the human body. This is consistent with the principle of Huygens, which defines the wave theory of light, and also the Huygens-Fresnel-Kirchhoff principle, which states that the intensity of light increases according to the magnitude of the angle of propagation of the light wavefront (${\theta}$).

Effects of vocal aerobic treatment on voice improvement in patients with voice disorders (성대에어로빅치료법이 음성장애환자의 음성개선에 미치는 효과)

  • Park, Jun-Hee;Yoo, Jae-Yeon;Lee, Ha-Na
    • Phonetics and Speech Sciences
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    • v.11 no.3
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    • pp.69-76
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    • 2019
  • This study aimed to investigate the effects of vocal aerobic treatment (VAT) on the improvement of voice in patients with voice disorders. Twenty patients (13 males, 7 females) were diagnosed with voice disorders on the basis of videostroboscopy and voice evaluations. Acoustic evaluation was performed with the Multidimensional voice program (MDVP) and Voice Range Profile (VRP) of Computerized Speech Lab (CSL), and aerodynamic evaluation with PAS (Phonatory Aerodynamic System). The changes in F0, Jitter, Shimmer, and NHR before and after treatment were measured by MDVP. F0 range and Energy range were measured with VRP before and after treatment, and the changes in Expiratory Volume (FVC), Phonation Time (PHOT), Mean Expiratory Airflow (MEAF), Mean Peak Air Pressure (MPAP), and Aerodynamic Efficiency (AEFF) with PAS. Videostroboscopy was performed to evaluate the regularity, symmetry, mucosal wave, and amplitude changes of both vocal cords before and after treatment. Voice therapy was performed once a week for each patient using the VAT program in a holistic voice therapy approach. The average number of treatments per patient was 6.5. In the MDVP, Jitter, Shimmer, and NHR showed statistically significant decreases (p < .001, p < .01, p < .05). VRP results showed that Hz and semitones in the frequency range improved significantly after treatment (p < .01, p < .05), as did PAS, FVC, and PHOT (p < .01, p < .001). The results for videostroboscopy, functional voice disorder, laryngopharyngeal reflux, and benign vocal fold lesions were normal. Thus, the VAT program was found to be effective in improving the acoustic and aerodynamic aspects of the voice of patients with voice disorders. In future studies, the effect of VAT on the same group of voice disorders should be studied. It is also necessary to investigate subjective voice improvement and objective voice improvement. Furthermore, it is necessary to examine the effects of VAT in professional voice users.

A Study on Environmental Impact Assessment Guidelines for Marine Environments in Harbor Construction Projects (항만건설사업의 해양환경 환경영향평가 가이드라인 개발 연구)

  • Maeng, Junho;Kim, Taeyun;Lee, Haemi
    • Journal of Environmental Impact Assessment
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    • v.31 no.3
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    • pp.141-160
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    • 2022
  • The harbor construction projects can lead to various marine environmental problems including habitat degradation and loss, marine water pollution, change of flow patterns, erosion, scour, sedimentation, and so on. The EIA is a measure to prevent various environmental problems in advance from examining and minimizing the environmental impacts before the proposed developments are implemented. In addition, institutions reviewing EIA reports have made efforts to conduct scientific and standardized EIA by applying EIA guidelines for each project. This study aims to create a EIA guideline focusing on the harbor construction projects. Based on the review comments of the harbor construction EIA reports for the past 13 years (2009-2021) and the EIA guidelines of different types of projects, we identified the marine environmental problems and provided the appropriate guideline. This guideline summarizes and presents the contents which must be reviewed in the baseline condition survey, impact assessment, mitigation, and post-environmental impact investigation in the fields of marine fauna and flora, marine physics, and marine water and sediment quality. In the case of a baseline condition survey of marine fauna and flora, a method for selecting survey points considering the characteristics of sea area and project was presented. When estimating the impact of marine fauna and flora, we presented methods for predicting the impact on them due to the spread of suspended sediments and the damage to benthic habitats due to dredging and reclamation. In consideration of the characteristics of the sea area, we divided the survey items of the marine physics into essential items and supplementary items. In predicting the impact of marine physics, various methods for major issues such as seawater circulation, suspended sediment and bottom sediment transport, water temperature and salinity diffusion, seawater exchange, wave transformation, harbor tranquility, and shoreline change were presented. The research results will contribute to protect the marine environment by inducing more systematic and scientific surveys, impact assessments, and mitigation in the EIA process.