• Radiation Oncology Journal
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• v.10 no.1
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• pp.1-6
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• 1992

The usefulness of hyperthermia for cancer therapy has been established. The purpose of the present investigation was to access feasibility of heating normal lung and the temperature and power requirement were compared with that for liver as solid organ in rabbits by using radiofrequent heating machine. In this study, 20 rabbits were divided into 2 groups according to the heating site and the method of temperature measurement; in group I : lung heating and temperature measuring in skin, esophagus and lung parenchyme; in group II : liver heating and temperature measuring in skin and liver parenchyme. The results were as follows; 1) When the maximum temperature was almost same in lung heating group and liver heating group, the power for liver heating was lesser required than the power for lung heating (p<0.05). 2) The temperature of esophagus for the measurement of mediastinum temperature was $1.1{\pm}0.9^{\circ}C$ higher than the temperature of lung parenchyme (p<0.05). Therefore the above findings suggest lung, air containing organ, is well heated as same as liver, solid organ. So more active trials of lung heating in the lung cancer must be likely considered. But when the lung is heated, the esophageal temperature is higher than lung parenchyme, so the mediastinum damage must be considered seriously.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.380-394
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• 2015

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. 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 heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were 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 thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance 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 was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.125-140
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• 2011

The remnant of temporary cement on the intaglio surface of cast restoration may have a negative effect on the retentive strength of permanent cement. This study was to evaluate the effect of temporary cement cleaning methods on the retentive strength of cementation type implant prostheses. Prefabricated implant abutments - height 5.5mm, diameter 4.5mm, 6 degree axial wall taper with chamfer margins were used. Forty copings-abutment specimens were divided into four groups(each n=10) according to the cleaning methods for temporary cement(Temp-$Bond^{(R)}$) as follows : no temporary cementation(the control group), orange solvent, ultrasonic cleaning, air borne-particle abrasion. After the application of temporary cement and the separation, the cleaning procedure was performed according to the protocol of each group. The specimens were cemented with $Premier^{(R)}$ Implant $Cement^{TM}$. After the permanent cementation, the specimens were subjected to thermocycling and pulled out from the specimens with a universal testing machine at a cross-head speed of 0.5mm/min. After the retentive strength test, all the specimens were cleaned using ultrasonic cleaning, abraded with air borne-particles, and steam-cleaned. Likewise, the specimens were temporarily cemented(Temp-$Bond^{(R)}$ NE), cleaned according to the protocol of each group, cemented with $Premier^{(R)}$ Implant $Cement^{TM}$ and subjected to thermocycling and measurement of their retentive strength. The mean of group with orange solvent were significantly lower than those of other groups(p<0.05). There was no significance between group with ultrasonic cleaning and group with air borne-particle abrasion. Group with ultrasonic cleaning and group with air-particle abrasion were no significance at control group. There was no significance between group cemented with Temp-$Bond^{(R)}$ and group cemented with Temp-$Bond^{(R)}$ NE. Within the limitation of this study, it can be concluded that the temporary cement cleaning method with only orange solvent may have a negative effect on the retentive strength of permanent cement. Ultrasonic cleaning and air borne-particle abrasion methods are recommended for the temporary cement cleaning method on cementation type implant prostheses.

• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.341-351
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• 2008

This study investigated the effect of intermittent polymerization on the rate of polymerization shrinkage and cuspal deflection in composite resins. The linear polymerization shrinkage of each composite was measured using the custom-made linometer along with the light shutter specially devised to block the light at the previously determined interval. Samples were divided into 4 groups by light curing method; Group 1) continuous light (60s with light on); Group 2) intermittent light (cycles of 3s with 2s light on & 1s with light off for 90s): Group 3) intermittent light (cycles of 2s with 1s light on & 1s with light off for 120s); Group 4) intermittent light (cycles of 3s with 1s light on & 2s with light off for 180s). The amount of linear polymerization shrinkage was measured and its maximum rate (Rmax) and peak time (PT) in the first 15 seconds were calculated. For the measurement of cuspal deflection of teeth, MOD cavities were prepared in 10 extracted maxillary premolars. Reduction in the intercuspal distance was measured by the custom-made cuspal deflection measuring machine. ANOVA analysis was used for the comparison of the light curing groups and t-test was used to determine significant difference between the composite resins. Pyramid showed the greater amount of polymerization shrinkage than Heliomolar (p < 0.05). There was no significant difference in the linear polymerization shrinkage among the groups. The Rmax was group 4 < 3, 2 < 1 in Heliomolar and group 3 < 4 < 2, 1 in Pyramid (p < 0.05). Pyramid demonstrated greater cuspal deflection than Heliomolar. The cuspal deflection in Heliomolar was group 4 < 3 < 2, 1 and group 4, 3 < 2, 1 in Pyramid (p < 0.05). It was concluded that the reduced rate of polymerization shrinkage by intermittent polymerization can help to decrease the cuspal deflection.

• Progress in Medical Physics
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• v.2 no.2
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• pp.109-120
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• 1991

Total body irradiation is operated to irradicate malignant cells of bone marrow of patients to be treated with bone marrow transplantation. Field size of a linear accelerator or cobalt teletherapy unit with normal geometry for routine technique is too small to cover whole body of a patient. So, any special method to cover patient whole body must be developed. Because such environments as room conditions and machine design are not universal, some characteristic method of TBI for each hospital could be developed. At Seoul National University Hospital, at present, only a cobalt unit is available for TBI because source head of the unit could be tilted. When the head is tilted outward by 90$^{\circ}$, beam direction is horizontal and perpendicular to opposite wall. Then, the distance from cobalt source to the wall was 319 cm. Provided that the distance from the wall to midsagittal plane of a patient is 40cm, nominal field size at the plane(SCD 279cm) is 122cm$\times$122cm but field size by measurement of exposure profile was 130cm$\times$129cm and vertical profile was not symmetric. That field size is large enough to cover total body of a patient when he rests on a couch in a squatting posture. Assuming that average lateral width of patients is 30cm, percent depth dose for SSD 264cm and nominal field size 115.5cm$\times$115.5cm was measured with a plane-parallel chamber in a polystyrene phantom and was linear over depth range 10～20cm. An anthropomorphic phantom of size 25cm wide and 30cm deep. Depth of dose maximum, surface dose and depth of 50% dose were 0.3cm, 82% and 16.9cm, respectively. A dose profile on beam axis for two opposing beams was uniform within 10% for mid-depth dose. Tissue phantom ratio with reference depth 15cm for maximum field size at SCD 279cm was measured in a small polystyrene phantom and was linear over depth range 10～20cm. An anthropomorphic phantom with TLD chips inserted in holes on the largest coronal plane was bilaterally irradiated by 15 minute in each direction by cobalt beam aixs in line with the cross line of the coronal plane and contact surface of sections No. 27 and 28. When doses were normalized with dose at mid-depth on beam axis, doses in head/neck, abdomen and lower lung region were close to reference dose within $\pm$ 10% but doses in upper lung, shoulder and pelvis region were lower than 10% from reference dose. Particulaly, doses in shoulder region were lower than 30%. On this result, the conclusion such that under a geometric condition for TBI with cobalt beam as SNUH radiotherapy departement, compensators for head/neck and lung shielding are not required but boost irradiation to shoulder is required could be induced.

• Journal of Preventive Medicine and Public Health
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• v.19 no.1 s.19
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• pp.16-30
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• 1986

In order to prepare the fundamental data for the improvement of noisy working environments and the effective hearing conservation program on workers exposed to industrial noise, the authors surveyed the working processes and evaluated the noise levels on 56 manufacturing industries in Pusan area from April to July in 1985. The results were summarized as follows : 1. The noise level was the highest in shipbuilding and repairing(95.6 dBA), and followed by steel rolling(94.0 dBA), manufacture of motor vehicles(93.1 dBA), manufacture of fishing nets(92.9 dBA), manufacture of testiles(92.5 dBA), iron and steel foundries(89.3 dBA), manufacture of metal products(89.1 dBA), preserving and processing of marine foods(87.0 dBA), manufacture of rubber products(85.3 dBA), manufacture of plywood(84.9 dBA) and manufacture of paints(84.5 dBA). 2. Among fifty surveyed working processes, the noise level of twenty-one processes (42%) exceeded the threshold limit value for 8 hours per day. 3. As the allowable exposure times by governmental threshold limit values to industrial noise level(dBA), cocking of shipbuilding and repairing and plating(CGL) of steel rolling were the shortest(30 minutes), and followed by assembling(rivet) of manufacture of motor vehicles(1 hour) weaving of manufacture of textiles and shot, machine, pipe laying of shipbuilding and repairing(2 hours). 4. By the result of octave band analysis on noisy working processes in excess of 90 dBA, the sound level was the highest at 2,000 Hz or 4,000 Hz. 5. It was recognized that the measurement of overall sound pressure level was also effective as octave band analysis in evaluating the industrial noise.

• Progress in Medical Physics
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• v.8 no.2
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• pp.3-17
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• 1997

Because a wedged beam consists of attenuated primary photons and scattered radiations from wedge, the spectrum of the wedged beam does not coincide with that of an open beam with same geometry. The aims of current report are to get exact information about whether effects of 15-60$^{\circ}$ wedge for 4 -10 MV photon beams should be considered for dose calculation or not, and to suggest a reference condition for measurement of wedge transmission factor. Percent depth dose of both open and wedged fields with angles of 15, 30, 45, 60$^{\circ}$ for beams of 4 MV(Clinac 4/100, Varian), two 6 MV(Clinac 6/100 and Clinac 2100C, Varian), 10 MV(Clinac 2100C, Varian) X-rays were measured to 30cm deep in water using ionization chambers. Hardening factors of photon beams were calculated with measured PDDs. Both field size factors and transmission factors of wedge filters were measured at d$_{max}$ in water. Beam hardening factors of wedged fields of 4 and 6 MV X-ray were larger than 1 for all wedge angles, field sizes and depths deeper than d$_{max}$ Beam hardening factors for wedge angles 15, 30, 45, 60$^{\circ}$ for 10$\times$10cm were respectively 1.010, 1.014, 1.023 and 1.034 for 4MV X-ray, 1.005, 1.008, 1.019, and 1.024 for 6MV X-ray of Clinac 6/100, 1.011, 1.021, 1.032, 1.036 for 6MV X-ray of Clinac 2100C, and 1.008, 1.012, 1.012 and 1.012 for 10MV X-ray. Beam hardening factors of 10MV X-ray were 1 within 1.2％ difference for all wedge angles, depths and field sizes. It was made clear that for 6MV X-rays, the beam hardening factor depends on treatment machine. The relationship of the factor and depth was linear. Field size factor at d$_{max}$ was independent of wedge angle except for the field of 15$\times$15cm. and maximum difference of the field size factors for the field size was 1.4％ for 4MV X-ray. When the wedge factor is determined, dependence of the factor on field size is negligible at d$_{max}$ but should be considered at deeper depth. Calculating dose distribution or MU, the beam hardening factor should be applied for 4~6MV X-ray beams, but might not be considered for 10MV beam. When wedge transmission factor was determined at d$_{max}$ or in air, field size factors for open field are also applicable to wedged fields, but otherwise, field size factor for each wedge or wedge factor depending on field size should be applied.

• Women's Health Nursing
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• v.7 no.2
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• pp.169-187
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• 2001

This study was performed to probe the effect of exercise program on muscle strength, endurance, flexibility, pain, disability level and life satisfaction in female teachers of elementary school who complain of low back pain. For this study, 44 female teachers aged 30-50 years with mechanical low back pain of 6 months' duration, who had the structural normalities in the lumbar spine, were recruited from April 1 to July 10 1999. Twenty three out of them were assigned to the experimental group and twenty one to the control group. The exercise program consisted of education on right postures, the etiology and diagnosis of low back pain, and exercise intervention such as muscle relaxation, elongation and strengthening. With 8 weeks program, the subjects received two sessions of education and six sessions of group exercise in the 1st week, while three sessions of group exercise and four sessions of individual exercise weekly and two sessions of education during the later 7 weeks. The muscle strength and endurance were measured by Cybex 770, the flexibility by flexibility measurement machine, the intensity of pain by Visual Analogue Scale (VAS), the level of disability by Oswestry low back pain disability scale, depression by Beck depression inventory (BDI), and life satisfaction by Life satisfaction index-Z. Study measurements were taken before and after 8 weeks exercise program. Data were analyzed using paired t-test, t-test, and ANCOVA. The results were as follows ; 1. The flexors and extensors peak torque and flexors peak torque per body weight of experimental group were significantly increased at test velocities $30^{\circ}$/sec, $60^{\circ}$/sec compared with those of control group. There was no significant difference in extensors peak torque per flexors peak torque at $30^{\circ}/sec$, $60^{\circ}/sec$ between experimental and control group. 2. The flexors and extensors total work and flexors total work per body weight of experimental group were significantly increased at $120^{\circ}/sec$, compared with those of control group. 3.The flexibility of lumbar spine in experimental group was significantly increased compared with that of control group. The pains in anterior, posterior, left lateral and right lateral bending and in rotation of experimental group were significantly increased compared with those of control group. 4. The Oswestry disability scores of experimental and control group were significantly decreased, and there was no difference in the Oswestry disability score change between experimental and control group. 5. The scores of BDI of experimental group were significantly decreased compared with those of control group. Life satisfaction index-Z scores of experimental group were not changed, but those of control group were significantly decreased. There was no difference in the score change of Life satisfaction index-Z between experimental and control group. 6. ANCOVA analysis for the data variables of inhomogeneous baseline represented that there was no significant difference in extensors peak torque and extensors total work at $120^{\circ}/sec$ and extensor total work per body weight at $120^{\circ}/sec$ change between experimental group and control group. These findings indicate that the exercise program could be effective in increasing the muscle strength, endurance, flexibility and decreasing pain, improving depression in female teachers of elementary school with chronic low back pain. It is suggested that the exercise program could be an essential factor for the effective nursing intervention to the patients suffered from chronic low back pain.

• Journal of the Korean Society of Radiology
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• v.7 no.2
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• pp.145-149
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• 2013

Helical Tomotherapy is an innovative means of delivering intensity modulated radiation therapy (IMRT) using a device that merges features of a linear accelerator and helical computed tomography (CT) scanner. Hereat, during helical tomotherapy process, megavoltage computed tomography (MVCT) image are usually used for guiding the precise set-up of patient before/after treatment delivery. But which would certainly increase the total dose for patients, this study was to investigate the imaging dose of MVCT using the cylindrical "Cheese" phantom on a tomotherapy machine. A set of cylindrical "Cheese" phantom was adopted for scanning with respectively pitch value (1, 2, 3 mm) with same number slice (10 slice), same length (approximately 9 cm) and phantom set-ups on the couch of tomotherapy system. The average MVCT imaging dose were measured using A1SL ion chamber inserted in the phantom with preset geometry. The MVCT scanning average dose for the cylindrical "Cheese" phantom was 2.24 cGy, 1.02 cGy, 0.81 cGy during respectively pitch value (pitch 1, 2, 3 mm) with same number slice (10 slice), and same length's average dose was 2.47 cGy, 1.28 cGy, 0.88 cGy respectively (pitch 1, 2, 3 mm). Two major parameters, the assigned pitch numbers and scanning length, where the most important impacts to the dose variation. The MVCT dose was inversely proportional to the CT pitch value. The results may provide a reliable guidance for proper planning design of the scanning region, which is valuable to help minimize the extra dose to patient. Questionnaires were distributed to Radiology departments at hospitals with 300 sickbeds throughout the Pohang region of North Gyeongsang Province concerning awareness and performance levels of infection control. The investigation included measurements of the pollution levels of imaging equipment and assistive apparatuses in order to prepare a plan for the activation of prevention and management of hospital infections. The survey was designed to question respondents in regards to personal data, infection management prevention education, and infection management guidelines.

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.173-185
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• 2018

Effects of three different types of dispersions and flow improving additives composed with fatty acid esters, fatty acid metal salts and amide compound on the vulcanization and the mechanical properties properties of rubber compounds of EPDM and carbon black as fillers. were investigated using Mooney viscometer, moving die rheometer, hardness tester, and universal test machine. The aging characteristics of vulcanized EPDM compounds were also investigated. The Mooney viscosity measured at $125^{\circ}C$ showed a tendency to decrease in the order of amide type> metal salt type > ester type additive. Scorch time showed little or no difference with the addition of ester or metal salt type additives, but the amide type additive shortened a scorch time more than one minute. Rheological measurement data obtained at $160^{\circ}C$ showed that the vulcanization time was faster for metal salt type and amide type additive systems. Delta torque values of EPDM compound increased with metal salt type and amide type additives, but slightly decreased with ester type additive. The tensile strength of the EPDM compound was greatly improved when an ester type additive was added, but the amide type or metal salt type additive had no significant effect. The elongation was significantly improved for metal salt type additive, while the rest were not significantly affected. The tear strength of the EPDM compounds increased with the addition of all kinds of additives, and it increased remarkably in the case of metal salt type additive. Hardness of the EPDM compounds was nearly same value regardless of additive types. The thermal aging of the EPDM blend at $100^{\circ}C$ for 24 h showed little change in the case of metal salt type or amide type additive, but the elongation tends to decrease by 10-20% for all EPDM compounds containing additives.