• Restorative Dentistry and Endodontics
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• v.31 no.5
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• pp.398-408
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• 2006

The purpose of this study was to verify the usefulness of MTT analysis as a tool of measurement of the periodontal ligament cell viability from the extracted rat molar. A total of 80 Sprague-Dawley white female rat of 4 week-old with a body weight of 100 grams were used. The maxillary left and right, first and second molars were extracted under Ketamine anesthesia. Twenty-four teeth of each group (divided as five groups depending upon the time-lapse after extraction such as Immediate, 10, 20, 40 and 60 minutes) were immersed in $200{\mu}l$ of MTT solution (0.5 mg/ml) and processed for optical density measurements. Another 10 teeth of each group were treated as same as above and sectioned at $10{\mu}m$ for microscopic examination. All measurements values were divided by the value of hematoxylin-eosin staining which represented the volume of each corresponding samples. Immediate and 10 minute groups showed highest MTT values followed by 20, 40, and 60 minutes consecutively. Statistical significance (p<0.05) existed between all groups except in immediate versus 10 minute groups and 40 versus 60 minutes. Histological findings also showed similar findings with MTT results in crystal shape and crystal numbers between the experimental groups. These data indicate that in vivo MTT analysis nay be of value for evaluation of the periodontal ligament cell viability without time- consuming cell culturing processes.

• Journal of Oral Medicine and Pain
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• v.32 no.3
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• pp.283-292
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• 2007

In several treatment modalities for snoring and obstructive sleep apnea (OSA), oral appliances mainly including mandibular advancement appliance (MAA) and tongue retaining device (TRD) are recognized as a non-invasive, reversible alternative with favorable results. Tongue bulb is a major component of TRD which prevents the tongue from approaching the posterior wall of the pharynx and can be combined with MAA. Determination of tongue bulb size for the patient is important for therapeutic effect, but frequently needs time-consuming work. For effective fabrication and standardization of tongue bulbs, this study aimed to categorize tongue bulb size for healthy young men and to examine its relation with maximum retention force and with physical parameters including tongue-related variables. 36 non-snoring, asymptomatic young men with normal occlusion were voluntarily participated in this study (mean age: $24.47{\pm}2.58$ years). Experimental procedures consisted of prefabrication of tongue bulb set (20 types with a width of 27-36mm and thickness of 8 and 10 mm), determination of tongue bulb size and the maximum retention force for each subject, and measurement of physical parameters including body mass index (BMI), neck circumference and width, thickness and length of tongue. This study showed that there was significant difference of retention force among the bulb size-related groups both in upright and supine position (p<0.05) and that retention force increased with bulb size. Correlation of tongue bulb size with physical parameters was not clearly verified and there was no significant difference in retention force between upright and supine positions. Based on our results, it can be suggested that retention force relates with tongue bulb size, ultimately with tongue volume. A further study needs to be performed in the patients with snoring and OSA.

• Progress in Medical Physics
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• v.23 no.4
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• pp.261-268
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• 2012

Breast cancer is the second leading cause of women cancer death in Korea. The key for reducing disease mortality is early detection. Although digital mammography (DM) has been credited as one of the major reasons for the early detection to decrease in breast cancer mortality observed in the last 20 years, DM is far from perfect for several limitations. Digital breast tomosynthesis (DBT) is expected to overcome some inherent limitations of conventional mammography caused by overlapping of normal tissue and pathological tissue during the standard 2D projections for the improved lesion margin visibility and early breast cancer detection. In this study, we compared a DM system and DBT system acquired with different thickness of breast phantom. We acquired breast phantom data with same average glandular dose (AGD) from 1 mGy to 4 mGy under same experimental condition. The contrast, micro-calcification measurement accuracy and observer study were conducted with breast phantom images. As a result, the higher accuracy of lesion detection with DBT system compared to DM system was demonstrated in this study. Furthermore, the pain of patients caused by severe compression can be reduced with DBT system. In conclusion, the results indicated that DBT system play an important role in breast cancer detection.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1977.06a
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• pp.4.4-5
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• 1977

The vibratory energy introduced into the external ear canal is changed by the mechanical factors of eardrum itself, the motility of ossicles, and the air cushion of tympanic cavity and the like. This study was designed to investigate the volume of middle ear cavity and mastoid air cell system as a factor of determining the accoustic impedance of middle ear system. The author studied how the increase in air volume of middle ear cavity effects on the acoustic impedance of middle ear system with dogs' ears and researched the correlation between the degree of pneumatization of temporal bones and the acoustic impedance of middle ear system by comparing the radiological findings of pneumatization (Law's and Towne's projection) with the acoustic impedance measurements with Madsen ZO 70. The result is as follows: 1 The tympanometric findings in control state revealed the curves of type A, and did not change in its configuration by the increase in the air volume of dogs middle ear system. 2. The static compliance of middle ear revealed a distinct and linear increase in proportion to the increase in air volume of middle ear system; the rate of increase was $0.05{\pm}0.02$ cc of static compliance per cc of air volume. 3. Authenticated in the above result and the tendency to increase in static compliance in proportion to the increase in the degree of pneumatization of temporal bones, there was significant regression equation between the degree of pneumatization of temporal bones (x variable) and the static compliance of middle ear system; $y=0.19x{\pm}0.16{\pm}0.05$ It is suggested that the difference in volume of middle ear system plays an important role in the change of the static compliance of middle ear, and the author concludes that the measurement of static compliance of middle ear has clinical value as diagnostic means of evaluating the degree of pneumatization of temporal bones along with some radiological examination.

• Journal of Korean Academy of Nursing
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• v.4 no.2
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• pp.93-106
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• 1974

The purposes of this study are to identify the necessity of utilization of electric thermometer, to determine the difference of clinical thermometers to reach maximum or optimum temperature, and to determine the length of time necessary for temperature taking, with Fahrenheit thermometer, electric thermometer, Yu Ⅱ centigrade thermometer, and Kuk ll centigrade thermometer. The first and second comparative Experiments were' conducted from August 25 through September 30, 1973. In the first experiment, Fahrenheit thermometer, which had been accurately teated two times, and electric thermometer have been utilized. These two kinds of thermometers were inserted simultaneously under the central area of the tongue and the mouth kept closed while thermometers were in place. All temperature readings were done at one minute interval until leaching-maximum temperature. These procedures were repeated one hundred times and the data were-analyzed statistically by means of the t-test. In the second experiment, Fahrenheit thermometer, which had been accurately tested two. times, Yu Ⅱ centigrade thermometer, and Kuk Ⅱ centigrade thermometer have been utilized. These three kinds of thermometers were inserted simultaneously under the central area of the. tongue and the mouth kept closed while thermometer were in place. All temperature readings were done at one minute interval until reaching maximum temperature. These procedures were. repeated one hundred times and the data were analyzed statistically by means of the F-ratio Under the eight hypotheses designed for this study, the findings obtained are as follows: 1. There were no significant differences in the maximum temperature between Fahrenheit thermometer and electric thermometer. The mean maximum temperature for Fahrenheit thermometers was 37.06℃ and for electric thermometer was 37.09℃. 2. The placement time to reach maximum temperature taken by Fahrenheit thermometer was significantly shorter than that by electric thermometer. The mean placement time for Fahrenheit thermometers was 4.04 minutes, for electric thermometer was 5.52 minutes. In the case of Fahrenheit thermometers, 45 to 77 percent after 3 to 5 minutes, over 90 Percent after 7 minutes, and 100 percent after 10 minutes, had reached optimum temperature. When the electric thermometer was used, 23 to 54 percent after 3 to 5 minutes, over 90 percent after 9 minutes, and 100 percent after 12 minutes, had reached optimum temperature. 5. There ware no significant differences in the maximum temperature among Fahrenheit thermometer, Yu Ⅱ centigrade thermometer, and Kuk Ⅱ centigrade thermometer. The mean maximum temperature for Fahrenheit thermometers was 36.67℃, for Yu Ⅱ centigrade thermometer, was 33.73℃, and for Kuk Ⅱ centigrade thermometers was 37.76℃. 6. There were no significant differences in placement time to reach maximum temperature among Fahrenheit thermometer, Yu Ⅱ centigrade Thermometer, and Kuk Ⅱ centigrade thermometer. The mean placement time (or Fahrenheit thermometers was 7.77 minutes, for Yu Ⅱ centigrade thermometers was 7.25 minutes, and Kuk Ⅱ centigrade thermometers was 7.25 minutes. In the case of Fahrenheit thermometers, 8 to 24 percent after 3 to 5 minutes, over 90 percent after 11 minutes, and 100 percent after 13 minutes, had reached maximum temperature. When the Yu Ⅱ centigrade thermometer was used, 10 to 27 percent after 3 to 5 minutes, over 90 percent after 11 minutes, an8 103 percent after 13 minutes, had reached maximum temperature. When the Kuk Ⅱ centigrade thermometer was used, 11 to 27 Percent after 3 to 5 minutes, over 90 percent after 11 minutes, and 100 percent after 12 minutes, had reached maximum temperature. 7. There were no significant differences in the optimum temperature(the maximum temperature minus 0.1℃) among fahrenheit thermometer, Yu Ⅱcentigrade thermometer, and Kuk Ⅱ centigrade thermometer. The mean optimum temperature for Fahrenheit thermometers was 36.60℃, for Yu Ⅱ centigrade thermometers was 36.69℃, and Kuk Ⅱ centigrade thermometers was 36.69℃. 8. There were no significant differences in placement time to reach optimum temperature among Fahrenheit thermometer, Yu Ⅱ centigrade thermometer, and Kuk Ⅱ centigrade thermometer The mean placement time for Fahrenheit thermometers was 5.70 minutes, for Yu Ⅱ centigrade thermometers was 5.54 minutes, and for Kuk Ⅱ centigrade thermometers was 5.28 minutes. In the case of Fahrenheit thermometers, 21 to 49 percent after 3 to 5 minutes, over 90 percent after 9 minutes, and 100 percent after 12 minutes, had reached optimum temperature. When the Yu Ⅱ centigrade thermometer was used, 23 to 51 percent after 3 to 5 minutes over 90 percent after 10 minutes, and 100 percent after 12 minutes, had reached optimum temperature. When the Kuk Ⅱ centigrade Thermometer was used, 23 to 57 Percent after 3 to 5 minutes, over 90 percent after 9 minutes, and 100 Precent after 11 minutes, had reached optimum temperature.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.6
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• pp.720-731
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• 2003

Statement of problem. The importance of fixture design and surface treatment. Purpose. The clinical success of dental in plants is affected by many factors such like as degree of osseointegration, the effective load dispersion for the prostheses, and a lot of attempts have been made to overcome the difficulties. In this study, efforts were made to find the possibility of clinical acceptance of the dental implants of newly designed surface and resorbable blast media surcace. Materials and methods. In this study, two groups of custom-made, screw-shaped implants were prepared. The first with the consisting of Branemark clone design and the other with the new design. These implants were divided into four groups according to the kinds of surface treatment. Four implants($AVANA^{(R)}$, Osstem, Busan, Korea)of each group were installed in twenty rabbits. Group A was consisted of Branemark done implant left as machined, Group B with Branemark clone implants with RBM(Resorbable blast media) surface, Group C with newly designed implants left as machined and Group D with newly designed implants with RBM surface. One of the twenty rabbits died from inflammation and the observation was made for six weeks. Specimens from four groups were observed using scanning electron microscopy with 40, 100, 1000 magnification power and microsurface structures were measured by white-light scanning interferometry for three dimensional surface roughness measurements(Accura $2000^{(R)}$, Intek-Plus, Korea.). Removal torque was measured in 17 rabbits using digital torque gauge(MGT 12R, Mark-10 corp., NY, U.S.A.) immediately after the sacrifice and two rabbits were used for the histologic preparation(EXAKT $310^{(R)}$, Heraeus Kulzer, wehrheim, Germany) of specimens and observed under light microscope. Resonance frequency measurement($Osstell^{(R)}$) was taken with the 19 rabbits at the beginning of the implant fixation and immediately after the sacrifice. Results. Following results were taken from the experiment. 1. The surface of the RBM implants as seen with SEM had rough and irregular pattern with reticular formation compared to that of fumed specimens showing different surface topographies. 2. The newly designed implant with RBM surface had high removal torque value among four groups with no statistical significance. The average removal torque was $49.95{\pm}6.70Ncm$ in Group A, $51.15{\pm}4.40Ncm$ in Group B, $50.78{\pm}9.37Ncm$ in Group C, $51.09{\pm}4.69Ncm$ in Group D. 3. The RFA values were $70.8{\pm}4.3Hz$ in Group A, $71.8{\pm}3.1Hz$ in Group B, $70.9{\pm}2.5Hz$, $72.7{\pm}2.5Hz$ in Group D. Higher values were noted in the groups which had surface treatment compared to the untreated groups with no statistical significance. 4. The results from the histomorphometric evaluation showed a mean percentage of bone-to-implant contact of $45{\pm}0.5%$ in Group A, $55{\pm}3%$ in Group B, $49.5{\pm}0.5%$ in Group C, and $55{\pm}3%$ in Group D. Quite amount of newly formed bone were observed at the surface RBM-treated implants in bone marrow space.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.359-364
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• 2008

We have investigated optical and structural properties of $Al_{0.3}Ga_{0.7}N$/GaN and $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ heterostructures (HSs) grown by metal-organic chemical vapor deposition, by means of Hall measurement, high-resolution X-ray diffraction, and temperature- and excitation power-dependent photoluminescence (PL) spectroscopy. A strong GaN band edge emission and its longitudinal optical phonon replicas were observed for all the samples. At 10 K, a 2DEG-related PL peak located at ${\sim}\;3.445\;eV$ was observed for $Al_{0.3}Ga_{0.7}N$/GaN HS, while two 2DEG peaks at ${\sim}\;3.42$ and ${\sim}\;3.445\;eV$ were observed for $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ HS due to the additional $Al_{0.15}Ga_{0.85}N$ layers. Moreover, the emission intensity of the 2DEG peak was higher in $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ HS than in $Al_{0.3}Ga_{0.7}N$/GaN HS probably due to an effective confinement of the photo-excited holes by the additional $Al_{0.15}Ga_{0.85}N$ layers. The 2DEG-related emission intensity decreased with increasing temperature and disappeared at temperatures above 150 K. To investigate the origin of the new 2DEG peaks, the energy-band structure for multiple AlGaN/GaN HSs were simulated and compared with the experimental data. As a result, the observed high- and low-energy peaks of 2DEG can be attributed to the spatially-separated 2DEG emissions formed at different AlGaN/GaN heterointerfaces.

• The Korean Journal of Physiology
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• v.15 no.2
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• pp.103-109
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• 1981

In order to determine the dose-response relationship of ethanol on blood pressure and renal function, 2 doses of ethanol were intubated into albino rats. For a direct measurement of arterial blood pressure, a polyethylene catheter(PE 10) was implanted in the abdominal aorta, and the other end of the catheter was pulled out of the back of the neck. The experiment was conducted after the rats recovered from the surgery. After emptying their bladders, the rats were placed in a metabolism cage. Mean arterial pressure (MAP) was measured and arterial blood samples were collected through the catheter. Following the collection of the control urine sample, 1 ml of 10 g% (low dose), or 30 g% (high dose) of ethanol/100 g BW was intubated. 1 ml of water/100 g BW was intubated into the control group. MAP and blood samples were taken every hour, and urine samples were collected every 90 min for 3 hours. Blood alcohol concentrations reached a peak at 1 hour (low dose: $105.0{\pm}7.5$, high dose: $214.7{\pm}20.2\;mg%$) and decreased linearly thereafter. Following alcohol ingestion, MAP began to decrease at 15 min and remained at a significantly low level thoughout the 3 hours experimental period(low dose: $112{\pm}2{\rightarrow}102{\pm}4$, high dose: $117{\pm}2{\rightarrow}100{\pm}8\;mmHg$). Urine Flow increased markedly during the first 90 min of ethanol ingestion (low dose: $0.88{\pm}0.20{\rightarrow}1.04{\pm}0.22$, high dose: $0.56{\pm}0.11{\rightarrow}1.35{\pm}0.18\;ml/1.5\;hr$) and decreased during the second 90 min period(low dose: $0.25{\pm}0.06$, high dose: $0.22{\pm}0.06\;ml/1.5\;hr$). Urine flow of the control group decreased gradually during the experiment $(0.88{\pm}0.10{\longrightarrow}0.59{\pm}0.09{\rightarrow}0.45{\pm}0.09\;ml/1.5\;hr)$. These results indicate that the blood-pressure-lowering and diuretic effects of ethanol are dose-related: higher doses of ethanol produce a greater decrease in blood pressure and greater diuresis.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.261-268
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• 2010

This study is compared that the dose distribution by experimentation and radiation therapy planning (RTP) when the air cavity region was treated high energy photon. The dose measurements were performed with a 6 MV photon beam of linear accelerator. The polystyrene and self made acyl phantom were similar to tissue density of the human body. A parallel plate chamber was connected to an electrometer. The measurement setup was SCD (Source Chamber Distance) 100 cm and the distance of surface from air cavity was 3 cm. Absorbed dose of interface were measured by area and height. The percent depth dose were measured presence and absence of air cavity, depth according to a ratio of field size and air cavity size. The dose distribution on planning was expressed to do the inhomogeneity correction. As the area of air cavity was increased, the absorbed dose were gradually reduced. It was slightly increased, when the height of air cavity was changed from 0 cm to 0.5 cm. After the point, dose was decreased. In case of presence of air cavity, dose after distal air cavity interface was more great than absence of air cavity. The rebuild up by field size and area of air cavity occurred for field size, $4{\times}4\;cm^2$, $5{\times}5\;cm^2$ and $6{\times}6\;cm^2$, with fixed on area of air cavity, $5{\times}5\;cm^2$. But it didn't occur at $10{\times}10\;cm^2$ field size. On the contrary, the field size was fixed on $5{\times}5\;cm^2$, rebuild up occurred in area of air cavity, $4{\times}4\;cm^2$, $5{\times}5\;cm^2$. but, it did not occur for air cavity, $2{\times}2\;cm^2$, $3{\times}3\;cm^2$. All of the radiation therapy planning were not occurred rebuild up. It was required to pay attention to treat tumor in air cavity because the dose distribution of planning was different from the dose distribution of patient.

• Journal of the Korean Society of Safety
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• v.10 no.3
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• pp.81-95
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• 1995

Now, safety assurance in construction sites should be accomplished by its own organization rather than control of the code or government. It is believed that the safety assurance can be considerably improved by a lecture or an education using the existing theories or literatures up to now, but it is thought that fundamental safety assurance we not able to be accomplished without developing safety devices '||'&'||' equipment or taking fundamental measures, based on the result analyzed from workers behaviors. There are various behaviors of the workers showed in construction site, but only tests for hammerusing works such as form, re-bar, stone workers directly related to the grip strength are mainly performed, investigated and measured here for the study. The above works are similar to power grip, 7th picture on seven items which are categorized for hand grip types(Ammermin 1956 ; Jones ; Kobrick 1958). Measurements of grip strength are commonly taken in anthropometric surveys. They are easy to administer but unfortunately it is rather dubious whether they yield any data that are of interest to the engineer. Very fewer controls of tools are grasped and squeesed studies showed very little overall correlation between grip strength and other measures of bodily strength (Laubach, Kromer, and Thordsen 1972), but hammer-using work which is practically progressed in construction site are mainly influenced with grip strength. According to the investigation on work measurement, it is shown that 77% of form worker are using hammer to be related to grip strength. In this study, it is particularly noticed that wearing safety gloves in construction site is required for workers safety but 20% difference between grip strength with safety gloves and without ones are commonly neglected in the site(Fig. 1). Nevertheless, safety operation with consideration of the above 20% difference is not considered in the construction site. Factors of age, kinds of work, working time, with or without safety gloves are in vestigated '||'&'||' collected at the sites for this study. Test, not at each working hour but at 14 : 00 when the almost all of the workers think the most tired, resulting from the questionaires, also when it is shown on the research report has been performed and compared for main kinds of works : form '||'&'||' re-bar work. Tests were performed with both left SE rightand of the workers simultaneously in construction site using Rand Dynamometer(Model 78010, Lafayette Instrument Co., Indiana, U.S.A) by reading grip strength on the gauge while they are pulling, and then by interviewing on their ages, works, experiences and etc., directly. The above tests have been performed for the dates of 15th march-26th May '95 with consideration of site condition. And even if various factors of ambient temperature on the testing date, working condition, individual worker's habit and worker's condition of the previous ate are concerned with the study. Those are considered as constants in this study. Samples are formwork 53, rebar 62, electrician 5, plumber 4, welding 1 from D construction Co., Ltd, ; formwork 12, re-bar 5, electrician 2, from S construction Co., Ltd, , formwork 78, re-bar 18, plumber 31, electrician 13, labor 48, plumber 31, plasterer 15, concrete placer 6, water proof worker 3, maisony 5 from B construction Co., Ltd. As In the previously mentioned, main aspect to be investigated in this study will be from '||'&'||' re-bar work because grip strength will be directly applied to these two kinds of works ; form '||'&'||' re-bar work, eventhough there are total 405 samples taken. It is thought that a frequency of accident occurrence will be mainly two work postures "looking up '||'&'||' looking down" to be mainly sorted, but this factor is not clarified in this study because It will be needed a lot of work more. Tests has been done at possible large scale of horizontally work-extended sites within one hour in order to prevent or decrease errors '||'&'||' discrepancies from time lag of the test. Additionally, the statistical package computer program SPSS PC＋has been used for the study.