• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.135-141
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• 2011

If protective performance of apron cannot be good, radiation exposure of an guardian or a patient, a person engaged in radiation related industry cannot rise. Therefore, It will be evaluated protection performance to radiation protection aprons by manufacturers and lead equivalent more than 0.25mm lead equivalent. And, will show in the direction of application to clinic. The new aprons by manufacturers(H, X, I, J company) and lead equivalent(0.50mmPb, 0.35mmPb, 0.25mmPb) measured transmitted dose rate and shielding rate, uniformity under fluoroscopy and general radiography using to fluoroscopy system and digital radiography system, x-ray multifunction meter. The shielding rate measurement results, 0.5mmPb apron was Shielding rate of apron of a I company(fluoroscopy : 97.96%) was the best under six companies, and shielding rate of apron of a J company(fluoroscopy : 96.25%) was worst. 0.35mmPb Apron was Shielding rate of a I company(fluoroscopy : 96.79%) was the best under the three companies, and shielding rate of an H company(fluoroscopy : 95.81%) was the worst. 0.25mmPb Apron was Shielding rate of X company apron(fluoroscopy : 90.908%) was better than H company apron(fluoroscopy : 88.82%) than two companies. The uniformity measurement results, 0.5mmPb Aprons of X company(fluoroscopy : 0.13) and I company(fluoroscopy : 0.19) was the best under the six companies, and J company apron(fluoroscopy : 0.45) was the worst. 0.35mmPb. Along a manufacturer and lead equivalent performance of apron protection is distinguished certainly. Therefore, a patient, guardian or a person engaged in radiation related industry shall enforce experiment of a lot of ways defined or evaluation so that the maximum reduces radiation exposure. Buy the apron that protective performance is good, It will be performed through experiment and evaluation.

• Journal of the Mineralogical Society of Korea
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• v.22 no.3
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• pp.241-248
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• 2009

Kaolinite was synthesized from amorphous $SiO_2$ and $Al(OH)_3{\cdot}xH_{2}O$ as starting materials by hydrothermal reaction conducted at $250^{\circ}C$ and $30\;kg/cm^2$. The acidity of the solution was adjusted at pH 2. The synthesized kaolinite was characterized by XRD, IR, NMR, FE-SEM, TEM and EDS to clarify the formational process according to the reaction time from 2 to 36 hours. X-ray diffraction patterns showed after 2 h of reaction time, the starting material amorphous $Al(OH)_3{\cdot}xH_{2}O$ transformed to boehmite (AlOOH) and after the reaction time 5 h, the peaks of boehmite were observed to be absent thereby indicating the crystal structure is partially destructed. Kaolinite formation was identified in the product obtained after 10 h of reaction and the peak intensity of kaolinite increased further with reaction time. The results of TGA and DTA revealed that the principal feature of kaolinite trace are well resolved. TGA results showed 13 wt% amount of weight loss and DTA analysis showed that exothermic peak of boehmite observed at $258^{\circ}C$ was decreased gradually and after 10 h of reaction time, it was disappeared. After 5 h of the reaction time, the exothermicpeak of transformation to spinel phase was observed and the peak intensiy increased with reaction time. The results of FT-IR suggested a highly ordered kaolinite was obtained after 36 hours of reaction. It was identified by the characteristic hydroxide group bands positioned at 3,696, 3670, 3653 and $3620\;cm^{-1}$. The development of the hydroxyl stretching between 3696 and $3620\;cm^{-1}$, depends on the degree of order and crystalline perfection. TEM results showed that after 15 h reaction time, curved platy kaolinite was observed as growing of (001) plane and after 36 h, the morphology of synthetic kaolinite exhibited platy crystal with partial polygonal outlines.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.101-111
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• 2017

Mineral carbonation is a technology in which carbonates are synthesized from minerals including serpentine and olivine, and industrial wastes such as slag and cement, of which all contain calcium or magnesium when reacted with carbon dioxide. This study aims to develop the mineral carbonation technology for commercialization, which can reduce environmental burden and process cost through the reduction of carbon dioxide using steel slag and the slag reuse after calcium extraction. Calcium extraction was conducted using NH4Cl solution for air-cooled slag and convert slag, and ${\geq}98%$ purity calcium carbonate was synthesized by reaction with calcium-extracted solution and carbon dioxide. And we conducted experimentally to minimize the quantity of by-product, the slag residue after calcium extraction, which has occupied large amount of weight ratio (about 80-90%) at the point of mineral carbonation process using slag. The slag residue was used to replace silica sand in the manufacture of cement panel, and physical properties including compressive strength and flexible strength of panel using the slag residue and normal cement panel, respectively, were analyzed. The calcium concentration in extraction solution was analyzed by inductively coupled plasma optical emission spectrometer (ICP-OES). Field-emission scanning electron microscope (FE-SEM) was also used to identify the surface morphology of calcium carbonate, and XRD was used to analyze the crystallinity and the quantitative analysis of calcium carbonate. In addition, the cement panel evaluation was carried out according to KS L ISO 679, and the compressive strength and flexural strength of the panels were measured.

• Journal of Radiation Protection and Research
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• v.14 no.1
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• pp.24-33
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• 1989

The peripheral dose, defined as the dose outside therapeutic photon fields, was estimated for 6MV X-ray linear accelerator. The measurements were performed using silicon diode detectors controlled by automatic controlled water phantom. The effects of field size, collimator position, presence or absence of wedge filter, and wedge angle were analyzed. The results were as follows 1. The peripheral dose decreases as the distance from field margin increases and it is more than 2.4% of central axis maximum dose even at 15cm distance from field margin. 2. Maximum build-up of peripheral dose is at 2-3 mm from the water surface and drops to a minimum at 1.5cm depth and then the dose increase again. 3. The peripheral dose increases as the field size. increases. At the short distance from field margin, the difference of peripheral dose between 5 $\times\;5cm^2$ and 20 $\times\;20cm^2$ field size reaches more than 2 fold. 4. The peripheral dose is higher along the upper collimator than along the lower collimator. The differences is less than 1%. 5. The presence of wedge filter increases peripheral dose. And the peripheral dose is higher along the blade side of wedge filter than along the ridge side. The difference is about 3% at 5cm distance from the field margin for 15 $\times\;15cm^2$ field size and 60$^{\circ}$ wedge filter. 6. The Peripheral dose of wedge filter increases as the wedge filter angle increases and the increasing ratio is about 2 fold in 60$^{\circ}$wedge filter compared with open field.

• Journal of the Speleological Society of Korea
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• no.74
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• pp.23-31
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• 2006

(1) Kaeusetgul Cave in Kimnyong-Ri, Jeju-Do, Korea. Kaeuset-gul Cave (KC) is situated in NNE area of the Manjang-gul cave (125m a.s.l.). Kaeuset-gul Cave lies at $126^{\circ}45'22"$ E in longitude and $33^{\circ}33'09"$ N in latitude. The coast belong Kimnyeong-Ri, Kujwa-eup, Jeju-Do. Altitude of the cave-entrance is 10m and length of the cave is 90m. Lava hand-specimens of KC are studied by X-ray fluorescence analysis (XRF). Average major chemical components of specimens from KC is as follows (wt.%); $SiO_2=47.03$, $TiO_2=3.16$, $Al_2O_3=18.41$, FeO*=13.53, MnO=0.14, MgO=5.05, CaO=8.66, $Na_2O=2.81$, $K_2O=0.67$, $P_2O_5=0.55$ in KC. Polarizing microscopic studyindicates that these specimens are described of alkali-basalt. (2) Tachibori Fuketsu (Cave) in Shizuoka Prefecture, Fuji Volcano, Japan Tachibori Fuketsu lies attoward the south in skirt of the Fuji volcano, $138^{\circ}42'04"$ east longitude and $35^{\circ}18'00"$ north latitude. The location of cave entrance is 2745, Awakura, Fujinomiya-shi, Shizuoka Prefecture. The above sea level and length of Tachibori Fuketsu are 1,170m and 82m. Average major chemical components of specimens from cave areas follows (Total 100 wt.%) ; ($SiO_2$=50.52, $TiO_2$=1.69, $Al_2O_3$=15.47, FeO*=13.13, MnO=0.20, MgO=5.97, CaO=9.17, $Na_2O$=2.52, $K_2O$=0.94 and $P_2O_5=0.40).$ Polarizing microscopic study indicates that these specimens may belong to tholeiite-basalt series. According to polarizing microscopic study, Au (Augite), P1 (Plagioclase), and O1 (Olivine) are contained as phenocryst minerals. (3) Gorely Cave in Kamchatka Peninsula, Russia Gorely caldera is located at the southeastern part of Kamchatka Peninsula, about 75km southwest of Petropavlovsk-Kamchatskiy.. Gorely lava caves are situated in NHE area of Mt. Gorely volcano (1829m a.s.1.). One of lava cave (Go-9612=K-1) lies at $158^{\circ}00'22"$ east longitude and $52^{\circ}36'18"$ north latitude. The elevation of cave entrance is about 990m a.s.1. and the main cave extends in the NNW direction for about 50m by 15m wide and 5m in depth. The cave of K-3is near the K-1 cave. "@Lava hand-specimens K-1 and K-3 caves are studied by X-ray fluorescence analysis and polarizing microscopic observation. Average major chemical components of specimens from these caves are as follows (wt.%) ;($SiO_2$=55.12, $TiO_2$=1.25, $Al_2O_3$=16.07, T-FeO* =9.41, MnO=0.16, MgO=5.01, CaO=7.21, $Na_2O$=3.39, $K_2O$=1.92, $P_2O_5$=0.45) and these values indicate that the Gorely basaltic andesite belong to high alumina basalt. Polarizing microscopic study indicates that these specimens are described of Augite andesite.

• Korean Journal of Digital Imaging in Medicine
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• v.5 no.1
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• pp.64-77
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• 2002

DR has had an important fact not only in the department of radiology but also in productivity or work efficiency of a whole hospital. The environment of DR has more various parameter than CR, so it is able to supply high quality of medical services. The current environment of radiology department in each hospital has been changed from Film-Screen system to DR through Full-PACS. This hospital which uses Full-PACS became to study the proper condition of CR and DDR and how the image quality of them is expressed among general photographing systems in the DR environment. From this experiment, the image quality of DDR is better than CR under the same exposure condition. And in the DDR system, the score of image which uses AEC is a little higher than the score which doesn't use it. Especially it can be known that the function of AEC of DDR is useful to improve the image quality in the part of skull and chest. (The function of AEC : It is the tool that detects the ionized current of x-ray which goes through objects with using the ion chamber which is in the detector. Also it controls the examination of X-ray when the proper density is reached.) Because the proper degree of density can be represented by this system, the photographing can be taken much easily without consideration of the exposure condition with the thickness of various objects. From the result of this experiment, it can be known that the selection of proper exposure condition plays an important rule to gain good Image Quality. More researches will be necessary about DDR system which has potential ability in the future.

• Radiation Oncology Journal
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• v.14 no.3
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• pp.237-244
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• 1996

Purpose : The accurate dosimetry of independent collimator equipped for 6MV and 15MV X-ray beam was investigated to search for the optimal correction factor. Materials and Methods : The field size factors, beam quality and dose distribution were measured by using 6MV, 15MV X-ray Field size factors were measured from $3{\times}3cm^2$ to $35{\times}35cm^2$ by using 0.6cc ion chamber (NE 2571) at Dmax. Beam qualities were measured at different field sizes, off-axis distances and depths. Isodose distributions at different off-axis distance using $10\times10cm^2$ field were also investigated and compared with symmetric field. Result: 1) Relative field size factors was different along lateral distance with maximum changes in $3.1\%$ for 6MV and $5\%$ for 15MV. But the field size factors of asymmetric fields were identical to the modified central-axis values in symmetric field, which corrected by off-axis ratio at Dmax. 2) The HVL and PDD was decreased by increasing off-axis distance. PDD was also decreased by increasing depth For field size more than $5{\times}cm^2$ and depth less than 15cm, PDD of asymmetric field differs from that of symmetric one ($0.5\~2\%$ for 6MV and $0.4\~1.4\%$ for 15MV). 3) The measured isodose curves demonstrate divergence effects and reduced doses adjacent to the edge close to the flattening filter center was also observed. Conclusion . When asymmetric collimator is used, calculation of MU must be corrected with off-axis and PDD with a caution of underdose in central axis.

• Radiation Oncology Journal
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• v.18 no.4
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• pp.251-256
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• 2000

Purpose : To evaluate efficacy and complication of stereotactic radiosurgery using stereotactic body frame. Methods and Materials :From December 1997 to June 1999, 11 patients with primary and metastatic tumors were treated with stereotactic radiosurgery using stereotactic body frame(Precision TherapyTu). Three patients were treated with primary hepatoma and seven with metastatic tumor from liver, lung, breast, trachea and one with arteriovenous malformation on neck. We used vacuum pillow for immobilization and made skin marker on sternum and tibia area with chest marker and leg marker. Diaphragm control was used for reducing movement by respiration. CT-simulation and treatment planning were peformed. Set-up error was checked by CT-Simulator before each treatment. Dose were calculated on the 80$\~$90$\%$ isodose of isocenter dose and given consecutive 3 fractions for total dose of 30 Gy (10 Gy/fraction). Results :Median follow-up was 12 months. One patient (9$\%$) showed complete response and four Patients (36$\%$) showed partial response and others showed stable disease. Planning target volumes (PTV) ranged from 3 to 111 cc (mean 18.4 n). Set-up error was within 5 mm in all directions (X, Y, Z axis). There was no complication in all patients. Conclusion :In Primary and metastatic tumors, stereotactic body frame is very safe, accurate and effective treatment modality.

• The Journal of Korean Society for Radiation Therapy
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• v.21 no.1
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• pp.1-7
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• 2009

Purpose: The purpose is to evaluate the accuracy of correcting the targeting error through the Target Location System (TLS) for the location change error of the reference point which arises from the movement or motion of patient during the treatment using the CyberKnife. Materials and Methods: In this test, Gafchromic MD-55 film was inserted into the head and neck phantom to analyze the accuracy of the targeting, and then the 6 MV X-ray of CyberKnife (CyberKnife Robotic Radiosurgery System G4, Accuray, US) was irradiated. End to End (E2E) program was used to analyze the accuracy of targeting, which is provided by Accuray Corporation. To compute the error of the targeting, the test was carried out with the films that were irradiated 12 times by maintaining the distance within the rage of $0{\pm}0.2\;mm$ toward x, y, z from the reference point and maintaining the angle within the rage of $0{\pm}0.2^{\circ}$ toward roll, pitch, yaw, and then with the films which were irradiated 6 times by applying intentional movement. And the correlation in the average value of the reference film and the test film were analyzed through independent samples t-test. In addition, the consistency of dose distribution through gamma-index method (dose difference: 3%) was quantified, compared, and analyzed by varying the distance to agreement (DTA) to 1 mm, 1.5 mm, 2 mm, respectively. Results: E2E test result indicated that the average error of the reference film was 0.405 mm and the standard deviation was 0.069 mm. The average error of the test film was 0.413 mm with the standard deviation of 0.121 mm. The result of independent sampling t-test for both averages showed that the significant probability was P=0.836 (confidence level: 95%). Besides, by comparing the consistency of dose distribution of DTA through 1 mm, 1.5 mm, 2 mm, it was found that the average dose distribution of axial film was 95.04%, 97.56%, 98.13%, respectively in 3,314 locations of the reference film, consistent with the average dose distribution of sagittal film that was 95.47%, 97.68%, 98.47%, respectively. By comparing with the test film, it was found that the average dose distribution of axial film was 96.38%, 97.57%, 98.04%, respectively, at 3,323 locations, consistent with the average dose distribution of sagittal film which was 95.50%, 97.87%, 98.36%, respectively. Conclusion: Robotic CyberKnife traces and complements in real time the error in the location change of the reference point caused by the motion or movement of patient during the treatment and provides the accuracy with the consistency of over 95% dose distribution and the targeting error below 1 mm.

• Tuberculosis and Respiratory Diseases
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• v.44 no.2
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• pp.290-297
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• 1997

Background : Despite remarkable progress of understanding the pathophysiology and therapy of bronchial asthma, asthma morbidity and mortality are on the rise. Also hospitalization and attending rates of emergency department for asthma have been increasing gradually. We analyzed clinical characteristics and prognosis of patients who visited emergency room due to asthma attack in order to define clinical characteristics of these group of patients. Method : We reviewed 105 adult asthmatic patients who attended emergency department of Korea University Hospital between August 1995 and July 1996, retrospectively. Results : 103 patients(56 female, 47 males, mean age : 48.6 years) attended-68 self referral, 18 practitioner referral and 17 OPD transfer- and 86 patients(83.5%) were admitted. Attending emergncy department was clearly more frequent in December(13.6%) and May(12.6%). Time lag between onset of asthmatic attack and arrival at the hospital was $14.2{\pm}15.5$ hour and initial peak expiratory flow rate was $166.7{\pm}68.3L/min$.(43.3% predicted) The commonest cause for visiting emergency room was aggravation of asthma due to upper respiratory tract infection in mild asthmatics. About half of them had history of previous ER visits. Their prognosis was not bad, but after discharge, about half of patients escaped from OPD follow-up. Conclusion : As a group they merit detailed attention and follow up arrangement. Clinician need to monitor and review the treatment plans, the medications, the patient's management technique, and the level of asthma control. For this group, plans for longer term treatment, including asthma education program and adjustment of overall treatment plan should be made.