• Journal of Oral Medicine and Pain
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• v.14 no.1
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• pp.113-121
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• 1989

In this study, 94 patients with temporomandibular disorders were interviewed to evaluate the effect of the treatment they received at the department of Oral diagnosis and oral Medicine in Seoul national university Hospital. The treatment administered to the patient were patient education, relaxation procedures, physical therapy, occlusal splint therapy and selective grinding of teeth. The following results were disclosed : 1. 97.9% of the patients reported no pain or considerably less pain than they had reported at their first visits to the department. 2. 89.3% of the patients thought that the treatment provided was either complete or considerably successful. 3. TMJ and facial pain was resolved within average 3.0 months 4. Of the 70 patients who previously reported having jaw joint sound, 34 patients (48.6%) no longer reported int. 5. Of the 48 patients who previously reported having headache regularly, 3 patients (68.8%) no longer reported headache regularly. 6. Of the 66 patients who previously reported having masticatory muscle pain, 41 patients (62.1%) no longer reported masticatory muscle pain. 7. Analysis of the data did not disclose a subgroup or factor, such as age, the stage of internal derangement, capsulitis, bruxism, MPD, duration of symptoms, that could be correlated with the reduction of pain or the patient's perception of success of treatment.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.57-63
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• 2002

In this paper, the feedforward control with least mean square (LMS) adaptive algorithm is proposed and examined to reduce rotating error by runout of an active magnetic bearing system. Using eddy-current type gap sensor fur control, the electrical runout caused by non-uniform material properties of sensor target produces rotational error amplified in feedback control loop, so this runout should be eliminated to increase rotating accuracy. The adaptive feedforward controller is designed and examined its tracking and stability performances numerically with established frequency response function. The tested grinding spindle system is manufactured with a 5.5 ㎾ internal motor and 5-axis active magnetic bearing system including 5 eddy current gap sensors which have approximately 15 ~ 30 ${\mu}{\textrm}{m}$ of electrical runout. According to the experimental analysis, the error signal in radial bearings is reduced to less than 5 ${\mu}{\textrm}{m}$ when it is rotating up to 50,000 rpm due to applying the feedforward control for first order harmonic frequency, and vibration of the spindle base is also reduced about same frequency.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.947-952
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• 1997

The magnetic polishing is the useful method to finish using magnetic power of a magnet. The time hasn't been that long since the magnetic polishing method was introduced to korea as one of precision polishing techniques. However, the reasons for not being spreaded widely are the magnetic polishing method don't have mediocrity for machine, the efficiency of magnet-abrasive is confined as a bad polishing, and there are not many researchers in this field. The mechanism of this R&D is dealing with the dynamic state of magnet-abrasive. This paper deals with mediocritizing magnetic polishing device into regular lathe and this experiment was conducted in order to get a best surface roughness with low cost. Beside the subsidiary experiment was performed using the mixed magnet-abrasive with general alumina, barium. This paper introduced the main reason for difficulty using this method in industrial field. It needs more continues research on it. This paper contains the result of experiment to acquire the best surface roughness, not using the high-cost polishing material in processing. The average diameters of magnet-abrasive are the particles of 150 $\mu\textrm{m}$, 250 $\mu\textrm{m}$.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.2
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• pp.19-25
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• 2005

In this paper, the feedforward control with least mean square (LMS) adaptive algorithm is proposed and examined to reduce rotating error by runout of an active magnetic bearing system. Using eddy-current type gap sensors for control, the electrical runout caused by non-uniform material properties of sensor target produces rotational error amplified in feedback control loop, so this runout should be eliminated to increase rotating accuracy. The adaptive feedforward controller is designed and examined its tracking performances and stability numerically with established frequency response function. The designed feedforward controller was applied to a grinding spindle system which is manufactured with a 5.5 kW internal motor and 5-axis active magnetic bearing system including 5 eddy current gap sensors which have approximately 15∼30㎛ of electrical runout. According to the experimental results, the error signal in radial bearings is reduced to less than 5 ,Urn when it is rotating up to 50,000 rpm due to applying the feedforward control for first order harmonic frequency, and corresponding vibration of the spindle is also removed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1427-1435
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• 2001

Air movement in wokplaces, whether resulting from a forced ventilation system or naturally occurring airflow, has a significant impact on occupational health. In a huge shipbuilding factory building, typical harmful factors such as fume or vaporized gas from welding and cutting of steel plates, and dusts from grinding give unpleasant feeling. From field data survey, the yearly dominant, wind directions for the shipbuilding factory building tested were northwest, northeast and southeast Among the three wind directions, the ventilation improvement was the worst for the northeastern wind. This study was focused on location of the opening vents in order to utilize the natural ventilation effectively. Instantaneous velocity fields inside the 1/1000 scale-down factory building model were measured using a 2-frame PIV system. The factory building model was embedded in an atmospheric boundary layer simulated in a wind tunnel. The modified vents improve the internal Ventilation flow with increasing the flow speed more than two times, compared with that of present vents.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.89-93
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• 2020

Complex warpage behavior of the electronic packages causes internal stress so many kinds of mechanical failure occur such as delamination or crack. Efforts to predict the warpage behavior accurately in order to prevent the decrease in yield have been approached from various aspects. For warpage prediction, silicon is generally treated as a homogeneous material, therefore it is described as showing no warpage behavior due to thermal loading. However, it was reported that warpage is actually caused by residual stress accumulated during grinding and polishing in order to make silicon wafer thinner, which make silicon wafer inhomogeneous through thickness direction. In this paper, warpage behavior of the single-side polished wafer at solder reflow temperature, the highest temperature in packaging processes, was measured using 3D digital image correlation (DIC) method. Mechanism was verified by measuring coefficient of thermal expansion (CTE) of both mirror-polished surface and rough surface.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.78-83
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• 2010

This paper presents the feasibility of incorporating ultrafine particles collected in the separator bag filter (separator bag filter cement, SBFC) during the cement manufacturing process as an substitution material for cement. SBFC does not require additional processes needed in the existing processes to manufacture high early strength cement such as modifying mineral components and adjusting the firing temperature. Moreover, it can also solve the issue of efficiency decrease resulted from the increase of the grinding time applied in the existing process of manufacturing microcement. Therefore, this research has examined the characteristics of SBFC and fresh properties and mechanical properties after making paste and mortar using SBFC in order to use SBFC as a material to gain early strength of concrete. For results, analyzing the chemical composition and physical properties of SBFC, its blaine value was $6,953cm^3/g$, about double than that of OPC, but its chemical composition showed no significant difference. According to the result of the paste and mortar examination, the paste and mortar mixed with SBFC showed a lower flowability, earlier setting time, and higher compressive strength than that with OPC. The result of microstructure analysis of paste, the paste mixed with SBFC indicated about 9% lower internal porosity at an early age than that of OPC. The compressive strength and flexural strength of mortar were higher in the order of SBFC ratio of 100, 50 and 0% SBFC.

• Design & Manufacturing
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• v.12 no.1
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• pp.41-46
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• 2018

This study proves the causes of cylinder and piston jam by scratches which is the fatal problem of hydraulic breaker through the thermal analysis and thermal-structural coupled field analysis. The trouble from the scratch is a complex problem which can be caused by manufacturing process (this is an internal factor) and the users mistake or contamination in the hydraulic circuit (these are an external factor). Hence, it's not easy to investigate the causes, also hard to prevent the recurrence. In this reason, hydraulic breaker manufacturers are trying to improve the manufacturing process such as machining, heat treatment, grinding, cleaning, also to prevent the contamination in hydraulic circuit and to remove the remains. It's being managed thoroughly by manufacturers. This study shows the effect of the temperature rise by the frictional heat generated when the piston hits the tool on the hydraulic oil while the hydraulic breaker is operating, also the temperature distribution when it starts to affect main components of hydraulic breaker. The stress and the amount of deformation also could be found through thermal-structural coupled field analysis. It proved that the stress and deformation are proportionally increased according to the temperature rise in hit area, and it affects the cylinder and the viscosity of hydraulic oil inside the cylinder when it heats up beyond the certain temperature.

• The Journal of Internal Korean Medicine
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• v.16 no.2
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• pp.146-177
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• 1995

The purpose of this study was to investigate the relationship between the teeth and Zhang-Fu(臟腑), dental diseases, and the hygiene of the mouth through the literature of oriental medicine. First, the relatonship between the teeth and Zhang-Fu is reviewed as follows: The teeth are influenced by Shen(腎) because they are the end of bone and Biao(標) of Shen. Gingiva is related to Wei(胃) and Da-Chang(大腸) because it is passed by Yangming-Channel(陽明經). The growth and nutrition of teeth depends on Shen. The pathological condition of Shen causes the gingival atrophy, the loose of teeth, dedentition due to aging, withering of teeth, and tartar: whereas the pathological condition of Wei and Da-Chang causes toothache, gingivitis, inflamed gums, bad breath, and gingival hemorrhage. Second, the causes and therapies of dental diseases through the literature can be summarized as follows: The major causes of toothache are the pathogenic condition of wind-heat and wind-cold, the heat syndrome of Wei, the damp-heat of intestine, flaring-up of fire of deficiency type, rotten tooth, etc... The principal causes of dedentition and the shaking and loose of teeth are the deficiency of Shen, and the rest of causes are the damp-heat of Yangming. Gingival atrophy is caused by the deficiency of Shen, whereas the gingival hemorrhage comes from the factors in the pathogenic factor of wind-heat of Yangming-Channel, the heat syndrome of stomach, and the deficiency of Shen. The causes of grinding of teeth during sleeping are stomach-heat, and the delayed dentition and the withering result from the deficiency of Shen-Jing.(腎精) The principal therapies of toothache are removing wind and heat, clearing away heat and prompting diuresis, clearing away the stomach-heat, replenishing vital essence to tonify the Shen, relieving superficial syndrome by wind-cold, and alleviating pain by destroying parasites. For the prescription of the principal therapies, there are Xijio Dihuang Tang, Jiajian Ganlu Yin, Qufeng Wan, Qingwei San, Tiaowei Chenggi Tang Shengong Wan, Liangge San Qingwei Tang Yunu Jian, Liuwei Dihuang Wan Zuogui Yin Bawei Wan Wanshao Dan, Xixin San Badou Wan Gianghuo Fuzi Tang, Jiuzi Tang Badou Wan, etc... The therapies of dedentition and the shaking and loose of teeth are replenishing vital essence to tonify the Shen, and warming and recuperating the Shen-Yang: as the prescription, there are Liuwei Dihuang Wana Zuogui Yin, and Bawei Wan Anshen Wan Wanshao Dan Yougui Wan etc... The therapies of gingival hemorrhage are clearing away the stomach-heat, replenishing vital essence to tonify the Shen, warming and recuperating the Shen-Yang(腎陽), and moisturing and purging intence heat with the prescription of Tiaowei Chenggi Tang Xijiao Dihuang Tang, Liuwei Dihuang Wan Zuogui Yin, Bawei Wan Anshen Wan, and Yunu Jian. The therapy of gingival atrophy is replenishing vital essence to tonify the Shen in the prescription of Liuwei Wan Bawei Wan Ziyin Dabu Wan. The therapies of grinding of teeth during sleeping are clearing away the stomach-heat and purging intense heat, and invigorating the spleen through eliminating dampness in the prescription of Qingwei San, Wumei Wan, etc... The therapy of delaed dentition is replenishing vital essence to tonify the Shen with the prescription of Liuwei Wan Buyin Jian, etc... Third, clinical treatment reports of dental diseases are reviewed as follows: The toothache due to stomach-heat was treated by medical herbs like Gypsum, Natrir Sulfas, Rehmanniae, Schizonepetal Herba, Menthae Folium, Cimicifugae Rhizoma, and Scrophulariae Radix. The therapies of toothache due to flaring-up of fire in deficiency type from deficiency of Shen provided with replenishment of vital essence to tonify the Shen and clean ministerial fire, and the prescription was the kind of Liuwei Wan, which worked very well. The therapy of dedentition and loose of teeth due to deficiency of Shen was done to stablize the teeth as tonifing the Shen with the prescription of Guchi Wan. The rate of imrovement was over 90%. The destruction of periodontal tissue due to periodonititis was cured of dispelling wind, reducing heat, and alleviating pain, It was improved by taking Zizhi Xingiong Tang, Guchi Xiaotong San, Yunii Jian, and Qingwei San about 3-7 days, and the rate of improvement was over 80%. Fourth, the prevention and regimens are reviewed as follows: As a physical and breathing exercise of the teeth, tapping teeth which stimulates the circulation of Qi(氣) and Xue(血) had been used. The tapping time of 14, 17, 36, etc... has been reported, and it should be applied based on the body condition. The medical herbs for gargling and brushing teeth have been used. Specifically, Cimicifugae Rhizoma, Gypsum, Gypsum Fibrosum, and Indigo pulrelrata Lereis have been used to reduce heat, Coptidis Rhizama and Yang Jinggu to eliminate damp-heat, Amomi Semen, Cyperi Rhizoma, Flos Caryophylli, Asari Radix, Piperis Longi Fructus, Santali Albae Lignum, Meliae Fructus, Moschus, Aquillaiae Lignum, and Borneol to promote the circulation of Qi and to relieve pain, Ligustici Radix, Angelice Radix, Rhizoma Nardostachydis, Tribuli Semen to relieve superficial syndrome by means of diaphiresis, and Cnidii Rhizoma, Angelicae sinensis Radix, and Olibanum to promote blood circulation to stop pain.

• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.79-84
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• 2014

This study has been performed for about 270 days at analyzing biologically hazardous factors in order to develop HACCP system for the non heat-frozen carrot juice. A process chart was prepared by manufacturing process of raw agricultural products of non heat-frozen carrot juice, which was contained water and packing material, storage, washing, cutting, extraction of the juice, internal packing, metal detection, external packing, storage and consignment (delivery). As a result of measuring Coliform group, Staphylococcus aureus, Salmonella spp., Bacillus cereus, Listeria Monocytogenes, Enterohemorrhagic E. coli before and after washing raw carrot, Standard plate count was $4.7{\times}10^4CFU/g$ before washing but it was $1.2{\times}10^2CFU/g$ detected after washing. As a result of testing airborne bacteria (Standard plate count, Coliform group, Yeast and Fungal) depending on each workplace, number of microorganism of in packaging room, shower room and juice extraction room was detected to be 10 CFU/Plate, 60 CFU/Plate, 20 CFU/Plate, respectively. As a result of testing palm condition of workers, as number of Standard plate count, Coliform group and Staphylococcus aureus was represented to be high as $6{\times}10^4CFU/cm^2$, $0CFU/cm^2$ and $0CFU/cm^2$, respectively, an education and training for individual sanitation control was considered to be required. As a result of inspecting surface pollution level of manufacturing facility and devices, Coliform group was not detected in all the specimen but Standard plate count was most dominantly detected in scouring kier, scouring kier tray, cooling tank, grinding extractor, storage tank and packaging machine-nozzle as $8.00{\times}10CFU/cm^2$, $3.0{\times}10CFU/cm^2$, $4.3{\times}10^2CFU/cm^2$, $7.5{\times}10^2CFU/cm^2$, $6.0{\times}10CFU/cm^2$, $8.5{\times}10^2CFU/cm^2$ respectively. As a result of analyzing above hazardous factors, processing process of ultraviolet ray sterilizing where pathogenic bacteria may be prevented, reduced or removed is required to be controlled by CCP-B (Biological) and critical level (critical control point) was set at flow speed is 4L/min. Therefore, it is considered that thorough HACCP control plan including control criteria (point) of seasoning fluid processing process, countermeasures in case of its deviation, its verification method, education/training and record control would be required.