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Verification of the Protective Effect of Functional Shielding Cream for the Prevention of X-ray Low-dose Exposure (X-ray 저선량 피폭방지를 위한 기능성 차폐크림의 방어 효과 검증)

  • Seon-Chil Kim
    • Journal of the Korean Society of Radiology
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    • v.17 no.4
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    • pp.497-506
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    • 2023
  • In the case of radiation workers in medical institutions, radiation exposure is made for patient protection and accurate procedures, so they have a problem of low dose exposure. Low-dose radiation exposure occurs mainly in parts of the body other than the Apron area, and the most frequent place is the skin of the back of the hand. In particular, since the medical personnel's hands require senses and fine movements during the procedure, they are defenseless in the radiation exposure area and are at risk of exposure. It can solve the problem of shielding such as lead gloves, and it is difficult to use by suggesting the activity of the hand during the procedure. To solve this problem, a shielding cream capable of obtaining a functional radiation protection effect was developed and its shielding performance was compared with lead equivalent of 0.1 mmPb. In the process of manufacturing shielding cream, the shielding performance was improved by adding a defoaming process to reduce air holes to increase the density of the cream. Therefore, the shielding cream using barium sulfate as the main material has a lower shielding rate than the lead plate, and in the realm of effective energy, it is 59%, At high effective energy, a difference of about 37% was shown, indicating that there is a functional radiation protection effect. The advantage is that it can be used directly on the skin, and it is considered that it can be used before wearing surgical gloves and has a permanent protective effect.

Studies on the Environmentally-friendly Production of Ginseng(Panaxs ginseng C.A. Mayer) by Lime Sulfur Treatment (석회유황합제를 이용한 청정 인삼 생산 연구)

  • Chang, K.J.;Sung, I.J.;Lee, S.S.;Ahn, C.H.;Byun, J.M.;Park, C.H.
    • Journal of Practical Agriculture & Fisheries Research
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    • v.15 no.1
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    • pp.183-202
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    • 2013
  • The demand of ginseng which has attracted many people for a long time has expanded further with great spotlight ; but it has caused anxiety of some safety-sensitive customers due to unavoidable pesticides and its weakness for disease and insect pest. On the other hand, sluggish studies on effective doses of ginseng and red ginseng which is produced and processed after hardship have worsened confusion of customers. Against this backdrop, this study is about to find out measures for safe ginseng cultivation and effective dose of white or red ginseng which are safely produced and reaches meaningful conclusions as follows ; As for a study to minimize the use of chemical fertilizers and pesticides or to change them into environmentally-friendly products, ginseng cultivation utilizing Lime Sulfur complex might be an alternative. The effects of Lime Sulfur complex are great on ginseng seeding with under 200 times compound KHCO3 and five-year-old ginseng with over 200 times compound using NaHCO3. When using with green materials like Bordeaux mixture, there would be great potential to realize ginseng without pesticide use.

Installation Damage Assessment of Geogrids by Laboratory Tester (실내 시험기에 의한 지오그리드의 시공 시 손상 평가)

  • Jeon, Han-Yong;Jin, Yong-Bum;Jang, Yeon-Soo;Yoo, Chung-Sik
    • Journal of the Korean Geotechnical Society
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    • v.23 no.7
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    • pp.77-86
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    • 2007
  • Installation damage of 3 types of geogrids was evaluated with compaction condition by laboratory tester. This experimental was in accordance with ENV ISO 10722-1. First, soil distribution and water content were conducted. And then we changed cyclic loading time and type of geogrids as a factor of installation damage. The samples are woven, warp-knitted, welded type of 6, 8, 10T. This study aims to give an insight into the relationships between installation damage and cyclic loading time. The result of studies was that strength of the damaged geogrids can be closely correlated with the time of loading cycles. Especially, welded type shows slower slope than two types of geogrids due to coating materials. That means welded type is coated with PP (Polypropylene), but the other two types of geogrids are coated with PVC (Polyvinyl Chloride). To confirm another factor different method was performed. The size of soil was used between 9.5 mm and 23.5 m to compare initial experimental. Cyclic loading compaction is taken 200 times before installation test and the reason is that the reduction factor of this case by installation damage was higher than other compaction loading conditions.

A Study on the Chinese Dai Tattoo Culture (두룽족 여성의 얼굴 문신 문화에 관한 연구)

  • Huo-Tao;Hee-Kyung Lim
    • Journal of the Korean Applied Science and Technology
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    • v.40 no.2
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    • pp.348-354
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    • 2023
  • A tattoo is a cultural form that has been handed down to mankind for a long time. Traditional tattoo customs that have been handed down and developed in the various cultures of mankind have the important value of academic research in various fields such as history, art, society, etc. The Derung people, one of the minorities living in Yunnan Province and nearby areas in the southwest of China, have 'facial tattoo' customs. The traditional culture of the Derung people, which had maintained the form of primitive society until 1949 when the People's Republic of China was established, was passed down through oral tradition, so there are no preserved materials about their tattoo culture, showing the need for research on the culture. Therefore, it was conducted in two ways: a research on modern and contemporary literature and a field trip to Yunnan Province. The exact reason and time of facial tattoo customs are unknown, but the customs disappeared after being banned in 1966 due to the Chinese Cultural Revolution. The symbols and functions of facial tattoos can be largely divided into four categories, including religious worship, coming-of-age ceremonies, aesthetic decorations, and ethnic and social history, through an on-site survey and research by modern and contemporary scholars. And, it is known that women of the Derung People get tattoos from the age of 7 to 8. The design of facial tattoos became more complicated for upper-class women and simpler for lower-class women depending on the area they live. Tattoos are mainly performed by relatives, and mainly bamboo skewers and lixivium extracted from the bottom of the pot are used as the materials. Currently, there are fewer than 25 women of the Derung people with facial tattoos, and most of them are elderly. Therefore, they seem to disappear altogether within a few decades. Therefore, it is urgent to have documentation on the unique facial tattoo culture of the Derung people.

The survey on foreign body ingestion and aspiration during the dental prosthetic treatment (치과 보철치료 과정에서 발생하는 이물질의 삼킴과 흡인에 대한 실태 조사)

  • Gi-Tae, Bang;Han-Sol, Jeon;Seon-Ki, Lee;Jae-In, Lee;Jin-Han, Lee
    • Journal of Dental Rehabilitation and Applied Science
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    • v.38 no.4
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    • pp.222-232
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    • 2022
  • Purpose: This study was to investigate the dentists' experience and awareness of foreign body ingestion and aspiration during dental prosthetic treatment. Materials and Methods: A survey of 157 dentists working at 108 dental institutions in Daejeon and Chungcheong provinces was carried out and frequency analysis was conducted. Chi-square test was conducted to find out the difference between the sociodemographic data and experience of foreign body ingestion and aspiration of patients and independent sample t-test was conducted to find out the difference in awareness depending on whether receiving related education. Results: The percentage of dentists experiencing dropping foreign body into patients' oral cavity was 99.4% and the percentage of dentists experiencing foreign body ingestion and aspiration of patients was 53.5%. There were more dentists who experienced foreign body ingestion and aspiration of patients in male than female, longer working career, and general practitioners than specialists (P < .05). 50.3% of the respondents received related education. When they receive related education, they had low degree of concern, high confidence in coping with situations, and low willingness to receive education in the future (P < .05). Conclusion: The percentage of foreign body dropping was 16% higher in prosthetic treatment than general treatment. The percentage of dentists with experience of foreign body ingestion and aspiration of patients was 53.5%. Among them, 92.9% experienced foreign body ingestion of patients and 7.1% of them experienced foreign body aspiration of patients.

Changes of bite force and dynamic functional occlusion analysis after occlusal stabilization splint therapy in sleep bruxism patients: a pilot study (수면이갈이 환자에서 교합안정장치 사용 후 교합력 및 동기능적교합분석: 예비 연구)

  • Jaeyeon, Kim;Yiseul, Choi;Yool Bin, Song;Wonse, Park;Seong Taek, Kim
    • Journal of Dental Rehabilitation and Applied Science
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    • v.38 no.4
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    • pp.204-212
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    • 2022
  • Purpose: The aim of this study was to compare changes of bite force, occlusal contact area, and dynamic functional occlusion analysis after occlusal stabilization splint therapy during sleep for one month in a patient with bruxism. Materials and Methods: From October 2021 to July 2022, sleep bruxism of 30 patients who visited the Department of Oral Medicine at Yonsei University College of Dentistry Hospital were recruited. The participants were divided into two groups: using an occlusal stabilization splint during sleep (treatment; n = 15) and not using an occlusal stabilization splint (control; n = 15). Before using the occlusal stabilization splint and one month after, bite force, occlusal contact area and dynamic functional occlusion analysis (ratio of left/right bite forces, average bite forces, maximum bite forces, and maximum contact areas during lateral and anterior and posterior mandibular movements) were performed. Results: There was no difference in bite force and occlusal contact area between the treatment group using the occlusal stabilization splint and the control group not using the occlusal stabilization splint during sleep for one month. However, there were significant differences in the average bite force and maximum bite force in the lateral and anterior and posterior mandibular movements and the maximum contact areas in the anterior and posterior mandibular movements. Conclusion: The occlusal stabilization splint is helpful for sleep bruxism patients who lateral and anterior and posterior mandibular movements. In addition, further studies are needed a double-blind study with a large population.

Reinforcement Effect of Cracked Concrete Tubes and Box Culverts by Installing Profile with Steel Stiffener and High Strength Mortar (스틸보강재가 부착된 프로파일 및 고강도 모르타르를 이용한 균열손상 콘크리트관의 보강효과)

  • Yeo, Sang Rok;Cho, Eun Sang;Hwang, Won Sup;Jeong, Jae Woon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1A
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    • pp.69-78
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    • 2008
  • In this study, in order to verify the reinforcement effects of the cracked concrete tubes and culverts, static load test was conducted. After the load carrying capacity of the original concrete tubes (nominal diameter 0.8 m, 1.0 m, 1.5 m) and box culverts (inner width 2.0 m. 2.5 m) was reduced by the cracking test, the cracked concrete specimens were strengthened by installing profile with steel stiffener and high strength mortar. And then, the maximum load tests were conducted the renewal concrete tubes and box culverts. According to the method application, the load carrying capacity increased 1.66~3.50 times than it of the original tubes before applying the method. In case of the original box culverts, the load carrying capacity increased 1.66~3.10 times than the case before installing profile and high strength mortar. Also non-linear analysis was carried out by using the commercial FEM program of ABAQUS 6.6. Solid (C3D8R) elements and concrete damage plasticity option was applied to the analysis. For reflecting confined reinforcing bars in the analysis, the composite material properties were used.

Predictive Equation of Dynamic Modulus for Hot Mix Asphalt with Granite Aggregates (화강암 골재를 이용한 아스팔트 혼합물의 동탄성 계수 예측방정식)

  • Lee, Kwan-Ho;Kim, Hyun-O;Jang, Min-Seok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3D
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    • pp.425-433
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    • 2006
  • The presented work provided a predictive equation for dynamic modulus of hot mix asphalt, which showed higher reliability and more simplicity. Lots of test result by UTM at laboratory has been used to develop the precise predictive equation. Evaluation of dynamic modulus for 13mm and 19mm surface course and 25mm of base course of hot mix asphalt with granite aggregate and two asphalt binders (AP-3 and AP-5) were carried out. Superpave Level 1 Mix Design with gyrator compactor was adopted to determine the optimum asphalt binder content (OAC) and the measured ranges of OAC were between 5.1% and 5.4% for surface HMA, and around 4.2% for base HMA. The dynamic modulus and phase angle were determined by testing on UTM, with 5 different testing temperature (-10, 5, 20, 40, & $55^{\circ}C$) and 5 different loading frequencies (0.05, 0.1, 1, 10, 25 Hz). Using the measured dynamic modulus and phase angle, the input parameters of Sigmoidal function equation to represent the master curve were determined and these will be adopted in FEM analysis for asphalt pavements. The effect of each parameter for equation has been compared. Due to the limitation of laboratory tests, the reliability of predictive equation for dynamic modulus is around 80%.

Fundamental Properties of Mortar with Magnet-Separated Converter-Slag Powder as SCM (자력 선별 전로슬래그 미분말을 결합재로 활용한 모르타르의 기초특성)

  • Beom-Soo Kim;Sun-Mi Choi;Jin-Man Kim
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.11 no.3
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    • pp.161-168
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    • 2023
  • Converter slag is a by-product generated by refining the pig iron produced into molten steel in the blast furnace, occupying about 15 % of the weight of steel production. It has a high free-CaO content that can generate expansion cracks when used for concrete aggregate. This is the main reason to make it difficult to recycle. To solve this problem, government guideline requires that converter slag has to be aged in an open yard for 90 days. However, aging can not be perfectly performed because it entails time and cost. In this study, we tried to investigate the applicability of converter slag as a cementitious material rather than an aggregate by mixing converter slag with mortar formulations. According to the EDS results of the converter slag in the experiment, we found that screening in the aggregate phase was more effective than that in the powder phase. When the particles separated by a magnet in the aggregate state were pulverized and used for concrete up to a 15 % replacement ratio, various engineering characteristics, such as flow, length change, and compressive strength, showed engineering characteristics similar to those of the control mix.

A Effect of Chemical Composition and Replacement Ratio of Limestone Admixture on Initial Cement Characteristics (석회석 혼합재의 화학성분과 치환량이 시멘트 초기 물성에 미치는 영향)

  • Dong-Kyun Suh;Gyu-Yong Kim;Jae-Won Choi;Kyung-Suk Kim;Ji-Wan Woo
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.11 no.4
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    • pp.440-448
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    • 2023
  • Utilizing admixture, which is one of the raw material replacement method in the cement industry, is expected to be easily and quickly put to practical use as it is relatively more accessible than other methods. Among cement admixtures, limestone powder is reported to be able to improve cement performance through nucleation effects, chemical effects, and filler effects, so it is a material expected to be suitable as a cement admixture. Meanwhile, as high-quality limestone is depleted around the world, the use of limestone with clay or high magnesia (MgO) content is becoming increasingly inevitable. Therefore, in this study, we attempted to evaluate the suitability of limestone cement as a admixture by measuring the basic properties of limestone cement mixed with limestone of different qualities commonly used in Korea. As a result, the effect of alite reaction promotion was confirmed regardless of the chemical composition of the limestone binder. However, the dilution effect depending on the substitution amount was greater than the chemical composition. It is believed that normal-grade limestone can be used as a mixture as long as the limestone content in cement is within 15 % in this scope of study. In the future, we plan to evaluate the impact of the chemical composition of the limestone mixture through additional experiments depending on the chemical composition of cement.