• Progress in Medical Physics
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• v.6 no.2
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• pp.13-19
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• 1995

The behavior of the correction factor associated with the collimator opening(head-scatter factor) were investigated for the 6MV x-ray beams of medical linear accelerator. The primary photon fluence was measured in air quasi-small fied size. Consideration in this study was given to the effect of head scatter factor with quasi-small fied size, the upper and lower collimator jaw scatter collection factors of quasi-small field (4-10cm) were measured with ion chamber. In general, the wedge factors which are used clinical practics are ignored of dependency on field sizes and depth. In wedge factors for each wedge filter were measured at various depth by using 6MV X-ray. In this present we inverstigated systematically the depth and field sizes dependency to determine the absorbed dose more accurately. Head scatter(upper-lower collimator jaw)appears to be (1) a small effect, less than 5％ over the range of clinical field sizes (2) generated primarily at the flattening filter and therefored influenced most by the upper collimator setting.

• Progress in Medical Physics
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• v.25 no.1
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• pp.15-22
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• 2014

The IMRT is proper implement to get high dose deliver to tumor as its shape and selective approach in radiation therapy. Since the IMRT is performed as modulated the radiation fluence by the MLC created the open shapes and its irradiation time, the dose of segment of radiation field effects on the cumulated portal dose. The accurate output factor of small and step shape of segment is important to improve the determination of deliver tumor dose as it is directly proportional to dose. This experiment performed with the 6 MV photon beam of Clinac Ex(Varian) from $3{\times}3cm^2$ to $0.5{\times}0.5cm^2$ small field size for collimator jaw in MLC free and/or for MLC open field in fixed collimator jaw $10{\times}10cm^2$ using the CC01 ion chamber, SFD diode, diamond detector and X-Omat film dosimetry. As results of normalized to the reference field of $10{\times}10cm^2$ of MLC, the output factor of $3{\times}3cm^2$ showed $0.899{\pm}0.0106$, $0.855{\pm}0.0106$ for $2{\times}2cm^2$, $0.764{\pm}0.0082$ for $1{\times}1cm^2$ and $0.602{\pm}0.0399$ for $0.5{\times}0.5cm^2$. The output factor of MLC open field has shown a maximum 3.8% higher than that of the collimator jaw open field.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.17 no.1
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• pp.233-248
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• 1987

The author studied the effect of periapical bone loss on radiographic interpretation by using a dry adult human mandible. Artificial bony lesions were created at the apices of two mandibular second molars and four mandibular bicuspids. The jaw was stabilized and various artificial lesions were radiographed under ideal circumstances. Radiographic pictures were recorded and compared with the size of the actual lesions. The obtained results were as follows: 1. The size of actual lesions were always larger than their radiographic pictures. 2. The size of actual lesion had a greater discrepancy in the molar area where the cortical plates were havier, but the lesions in the bicuspid areas were only slightely larger than their radiographic pictures, and in these areas the cortical plates were quite thin. 3 Periapical lesions located in cancellous bone did not appear on a radiograph, regardless of the size of the created lesion, but when the junctional bone was involved or the cortical plate was perforated, the definite bone destructive change was observed on the roentenogram. 4. Removal of the entire buccal or lingual plate did not affect the trabecular pattern of bone on the roentgenogram. 5. When the cancellous bone and junctional bone were removed simultaneously, altered trabecular patterns were observed on the roentgenogram.

• Resources Recycling
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• v.26 no.4
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• pp.71-78
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• 2017

This study investigated the recovery of metallic aluminium in the black dross generated from used beverage can recycling process with crushing mechanism such as compression and impact. The as-received Al black dross had a spherical shape, and its size was about 10~40 mm. Also, The X-ray diffraction pattern showed that the main contents of black dross are composed of halite (NaCl), sylvite (KCl), spinel ($MgAl_2O_4$) and corundum ($Al_2O_3$). A metallic aluminium recovery test was performed using jaw crusher and hammer mill having different crushing mechanism. It was analysed that Jaw crushing process can separate into metallic aluminium and non metallic constituents. However, hammer milling process shows significant difference on the separation results. It was found that jaw crushing process was effective for recovery of metallic aluminium in the black dross than that of hammer milling process.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.4
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• pp.286-290
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• 2010

Various treatment methods for huge cystic lesion of the jaw exist, such as, resection of the involved bone, enucleation and decompression. Among these methods, enucleation after decompression is a conservative technique that decreases the size of the cystic cavity and reduces the risk of intrabony defects, which could be induced by primary enucleation. In addition, it can save the adjacent anatomic structures. In these cases, the decompression combined with partial enucleation, which was performed before complete cyst enucleation was performed on huge cystic lesions of the mandible. During the process, a decrease in the size of the lesion and the growth of normal oral tissues was observed. The size of the lesion decreased until the time of complete enucleation, and surgery could be performed under local anesthesia. No damage to inferior alveolar nerve was observed. We report these cases with a review of the relevant literature.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.3
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• pp.229-236
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• 2009

Purpose: Some recent literatures report that it is possible to recover defected areas caused by enucleation of relatively large jaw cysts without using bone grafts. The aim was to find out whether spontaneous recovery of defected area with time occurred and what the contributing factors were. Materials and methods: In total, 194 patients were considered as patients. Out of these 194 patients, 74 patients who had no wound dehiscence and who were available for follow-up studies were selected. They were classified into two groups according to the size of radiolucent area in the preoperative panoramic radiographs: in one group, it was larger than $3{\times}4cm$, while in the other group, it was smaller than $3{\times}4cm$. Follow-up panoramic radiographs were taken immediately after the surgery, then after 3, 6, 9 and 12 months. On those radiographs, changes in size and density of the defected areas were observed using the Gray-level histogram of Adobe photoshop v7.0. Correlation between bone regeneration and factors such as the type and size of the cysts, age, sex, site of the cysts and systemic disease was evaluated using the General repeated measure and Mann-Whitney Test. Results: Analyses of panoramic radiographs showed that the recovery of radiopacity after 12 months was more than 97% on average in defected areas that were smaller than $3{\times}4cm$. in the defected areas that were larger than $3{\times}4cm$, considerable portion showed recovery of radiopacity. No statistically significant change was observed in bone density according to the type of cysts. Young patients under 20 years of age with highly active metabolism presented more significant bone regeneration than patients over 20 years of age. Bone regeneration was more hampered in patients who had medical disease, compared with patients who didn’t have any medical problem. No statistically significant change was seen in bone density according to sex. Changes in bone density according to the site of cysts such as maxilla, mandible, anterior or posterior region were not considered to be significant. Conclusion: Analyses of panoramic radiographs suggest that in approximately 12 months after the enucleation of cysts, clinically acceptable spontaneous bone regeneration can be observed even though normal bone graft procedures have not been applied.

• Korean Journal of Ichthyology
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• v.13 no.4
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• pp.237-247
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• 2001

Three species, Gymnogobius urotaenia, G. sp. 1 and G. sp. 2, which were collected at Hosanriver, Hosan-ri, Samcheock-si, Gangwon-do, Korea, were examined for study of the age and growth. There was no differences between sexes in growth (p>0.05) except in age 0 of G. urotaenia, However, there were differences among the three species (p<0.0001). namely, G. sp. 1 was longer by about 5~10 mm (SL) than the other two species in each age group, while G. sp. 2 was shortest in each age group: G. rotaenia, at age 0 was less than 45 mm, at age 1 to be 45~60 mm, at age 2 to be 60~80 mm, at age 3 to be over 80 mm, and its maximum size was 105.0 mm. G. sp. 1, at age 0 was less than 55 mm, at age 1 55~65 mm, at age 2 65~85 mm, at age 3 over 85 mm and its maximum size was 105.3 mm. G. sp. 2, 0 age was less than 40 mm, at age 1 40~55 mm, at age 2 55~75 mm, at age 3 over 75 mm and its maximum size was 85 mm. Changes of body parts with increasing of body length were examined and analyzed. Covariance analysis showed interspecies differences in the following characters: body depth, head length, caudal peduncle depth, upper jaw length and pelvic fin ray length. G. urotaenia had the highest K-value (the relative growth coefficient) in head length and pelvic fin ray length, and G. sp. 1 had the highest in body depth, caudal peduncle depth and upper jaw length. However, G. sp. 2 had the lowest K-value in these 5 characters.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.383-395
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• 2008

To enhance the grade and recovery rate of the gold/silver ores which yield at Philippine Mankayan mine, we studied the characteristics which are the geologic and mineralogical features of gold and silver ore, the liberation by crushing and grinding, the separation by sieving and shaking table. Gold/silver ore is composed of the sulfide minerals like pyrite, sphalerite, galena; and the gangue minerals which is quartz, clay. Gold/silver element are mainly contained in a sulfide minerals like pyrite, sphalerite and galena. To increase the liberation rate of sulfide minerals containing gold/silver element, the gold/silver ore has to be grounded under $100{\mu}m$ very finely because the crystal size of sulfide minerals is distributed from $1{\mu}m$ to $100{\mu}m$. The liberation rate of gold/silver ore increases to 92% when the particle size ($d_{90}$) of ore is grounded below $100{\mu}m$ by jaw crusher $\to$ cone crusher $\to$ rod mill by steps. The grade and recovery of sulfide minerals could not be enhanced by sieving separation because those crystal size is distributed homogeneously below $100{\mu}m$. But, when we separated the sieved ore using shaking table, the gold and silver grade increased to 40 ppm and 140 ppm, respectively. Then the recovery rate of gold reach almost 100% but that of silver is no more that 50%.

• The korean journal of orthodontics
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• v.46 no.2
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• pp.111-126
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• 2016

Objective: To systematically review previous studies and to assess, via a subgroup meta-analysis, the combined odds ratio (OR) of prognostic factors affecting the success of miniscrew implants (MIs) inserted into the buccal posterior region. Methods: Three electronic searches that were limited to articles on clinical human studies using MIs that were published in English prior to March 2015 were conducted. The outcome measure was the success of MIs. Patient factors included age, sex, and jaw of insertion (maxilla vs. mandible), while the MI factors included length and diameter. A meta-analysis was performed on 17 individual studies. The quality of each study was assessed for non-randomized studies and quantified using the Newcastle-Ottawa Scale. The meta-analysis outcome was a combined OR. Subgroup and sensitivity analyses based on the study design, study quality, and sample size of miniscrews implanted were performed. Results: Significantly higher success rates were revealed for MIs inserted in the maxilla, for patients ${\geq}20$ years of age, and for long MIs (${\geq}8mm$) and MIs with a large diameter (> 1.4 mm). All subgroups acquired homogeneity, and the combined OR of the prospective studies (OR, 3.67; 95% confidence interval [CI], 2.10-6.44) was significantly higher in the maxilla than that in the retrospective studies (OR, 2.10; 95% CI, 1.60-2.74). Conclusions: When a treatment plan is made, these risk factors, i.e. jaw of insertion, age, MI length, and MI diameter, should be taken into account, while sex is not critical to the success of MIs.

• Journal of Sasang Constitutional Medicine
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• v.22 no.2
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• pp.37-47
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• 2010

1. Objectives: We aimed to derive constitutional facial characteristics with front and side picture of the people in this study 2. Methods: Through November 2007 to July 2009, we obtained front and side face photograph data of 715 male/female constitution confirmed subjects within the age range of 10-80 from 19 oriental medical facilities in the country. According to sex, we divided the subjects into two groups, real constitution group and non-constitution group. We analyzed significant variables of distance, angle and ratio of facial point through unpaired T-test. 3. Results: There are different significant variables according to Sasang Constitution and even though they are much different between sex, the interpretation of the meaning of those variables are similar with the written characteristics of ancient Writing. The face size of the Taeeumin is bigger than that of the non-Taeeumin, and especially they have long length from mouth to mandible angle. Soeumin have small jaw area, long philtrum and narrow facial feature like egg. Soyangin has developed forehead and glabella, short jaw, long eye side. Taeyangin has developed forehead, weak nose especially side end of nose, long eye side. 4. Conclusions: Sasang Constitutional facial characteristics are different between man and woman but there are much similarity with the facts as known on the interpretation of significant variables characteristics.