• 구강회복응용과학지
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• 제24권3호
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• pp.283-298
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• 2008

이 연구의 목적은 내측연결 임플랜트 시스템의 고정체-지대주-나사간의 계면 적합도를 알아보기 위한 것이다. 실험에 이용된 임플랜트 시스템은 Certain, Xive, Replace, Ankylos, SSII 이다. 이 시스템의 고정체와 지대주를 제조사의 권장 토크로 조인후 액상의 불포화 폴리에스터 용액에 고정한 후 절단하였다. 모든 표본은 절단, 연마후 주사전자 현미경으로 관찰하였다.내측연결 시스템의 적합도를 관찰한 결과, 각 제조사들 사이에 차이는 있으나 대부분의 내측연결 시스템의 경우엔 고정체와 지대주의 접촉은 긴밀히 접촉하는 경향을 가지고 있음을 알 수 있었다. 그러나 지대주와 나사, 고정체와 나사 간에는 다양한 형태의 틈이 존재하였다. 이러한 틈들이 나사의 불안정, 미생물의 군집, 악취 등에 어떠한 영향을 미칠지는 앞으로 계속적인 연구가 필요할 것으로 사료된다.

• 펄프종이기술
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• 제45권4호
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• pp.34-41
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• 2013

In this study, we investigated the physical properties of powders made from agricultural byproducts, including rice straw, peanut husks, and garlic stems, to manufacture a new organic filler used for making paperboard. These materials were collected individually, and then we measured their chemical compositions. The byproducts were ground with a laboratory grinder and fractionated with 60-, 100-, and 200-mesh sieves to make many grades of organic fillers. After the grinding and fractionation, the yield, mean particle size, and particle size distribution of each grade were measured. Particle shapes were also investigated using a scanning electron microscope. The organic filler made from rice straw had the highest yield of the largest particle size group and higher contents of cellulose and hemicellulose than those made from peanut husks and garlic stems. The rice straw also showed more regular particle shapes and a lower aspect ratio than the other agricultural byproducts.

• 생물환경조절학회지
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• 제9권2호
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• pp.73-78
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• 2000

본 연구에서는 유기물 재료로 구득이 쉽고 수량이 풍부하며 재료의 균일성이 좋은 왕겨를 팽연화 하여 양액재배용 배지 재료 사용하기 위해 적합한 조건을 탐색해 보았다. 팽연화 왕겨의 물리성은 CEC 37.0cmol.kg-1, 가비중 0.19g.㎤, -0.1 bar 상태에서 보수력 271.0으로 펄라이트보다 우수하였으나 흡수속도는 펄라이트에 크게 떨어지는 경향이었다. 팽연화 수준이 높아짐에 따라 보수력, 흡수속도 등 수분관련 물성이 좋아지는데 반해 입도가 작아지고 부숙속도가 빨라지는 변화가 있었고 재배중 부숙이 진행됨에 따라 급액 15일 이후부터 pH가 상승되며 15~20일 사이에 NO3 부족이 심화되어 작물에 스테레스를 주는 것으로 판단되었다. ERH a처리에서 당도가 펄라이트에 비해 약 1.0 。Brix정도 높고 수량의 유의성은 없었으므로 틈새간극 8mm, 날높이 3mm에서 생산된 팽연화 왕겨의 물성이 양액재배용 배지 재료로 사용하기에 적정하였다.

• Archives of Plastic Surgery
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• 제46권1호
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• pp.63-68
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• 2019

Background Hand injuries caused by chain saws, electric saws, and hand grinders range from simple lacerations to tendon injuries, fractures, and even amputations. This study aimed to understand the distribution of various types of hand and upper extremity injuries caused by power tools, in order to help prevent them, by investigating the incidence and cause of power tool injuries treated over a 4-year period at a single institution in Korea. Methods We reviewed the medical records of patients who visited a single institution for power tool-induced injuries from 2011 to 2014. The distribution of sex, age, injured body part, type of injury, and mechanism of injury sustained by patients who received hand and upper extremity injuries from using an engine saw, electric saw, or hand grinder was evaluated. Results Among 594 subjects who were injured by power tools, 261 cases were hand and upper extremity injuries. The average age was 53.2 years. Tendon injury was the most common type of injury. An electric saw was the most common type of power tool used. More injuries occurred in non-occupational settings than in occupational settings. Conclusions In this study, power tool-induced hand and upper extremity injuries were mostly caused by direct contact with electric saw blades. More injuries occurred due to non-occupational use of these tools, but the ratios of amputations and structural injuries were similar in the non-occupational and occupational groups.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.297-297
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• 2022

Wheat is the staple food crop in the word, but wheat products have a low bioavailability of iron and zinc. So in the developing world, where wheat is a staple food, it suffers from micronutrients deficiency. This study was conducted to generate wheat varieties with enhanced grain Zn and Fe contents. Sixty wheat resource were cultivated over 2 years (2019-2021) in the field of NICS, Jeonju, Republic of Korea, to identify agronomic traits. Wheat grains were ground using grinder and analyzed whole wheat flour protein contents and Fe and Zn contents using ICP-OES. The average contents of Zn and Fe grain were 4.6 mg/100g (2.4~8.8 mg/100g) and 4.5 mg/100g (2.4~7.9 mg/100g), respectively. The contents of Fe and Zn in the wheat grain had a positive correlation with the protein content of whole wheat flour, but there was no correlation with heading date (4.22~5.27) and the thousand kernel weight (21.3~57.5 g). Although there was year variation, six resources with high contents of Fe (>5.2 mg/100 g) and Zn (>5.3 mg/100 g) grain in 2 years were selected. These results provide information for selecting breeding materials for biofortified wheat, and further studies on germplasms genetic variations and bioavailability are needed.

• 생명과학회지
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• 제19권4호
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• pp.486-491
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• 2009

본 연구는 생산 후 3일 이내인 시판두부의 가공공장별, 두부유형별 위생실태를 파악하여 두부에 대한 미생물 규격의 설정 가능성을 검토하며, 가공단계별 총생균수와 대장균군을 분석하여 오염 원인을 규명코자 실시되었다. 시판중인 두부의 위생성은 동일유형이더라도 가공공장마다 차이가 있었고 동일공장의 시료 간에도 차이를 보였다. 총생균수가 $1.0{\times}10^6CFU/g$ 이상을 보인 일부 포장두부에서는 관능적 부패 변질 현상이 관찰되었다. 총 148개 두부시료 중 총생균수와 대장균군이 각각 $1.0{\times}10^5CFU/g$ 이하와 음성에 적합한 시료는 단순포장두부가 32.0%와 12.0%, 포장가열두부가 86.9%와 83.7%인 것으로 조사되었다. 이러한 가공공장에 따른 위생성 차이는 가열과 열처리사이의 공정인 응고, 압착, 성형, 1차냉각, 내포장공정에서 2차오염 정도의 차이에서 기인하는 것으로 생각되었다. 포장두부의 가공공정 중 미생물이 증가하여 각별한 관리가 요구되는 공정으로는 원료대두의 세척 침지와 마쇄, 응고 후 압착 성형, 1차냉각공정이었다. 따라서 보다 위생적인 두부를 가공하기 위해서는 이들 가공공정에서 사용되는 각종 설비나 작업도구, 성형포 및 작업자 등에 대한 세척 및 소독 강화가 절실하게 요구되었다.

• 대한치과보철학회지
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• 제41권4호
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• pp.503-518
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• 2003

Statement of problem : There have been previous studies about considerable variations in machining accuracy and consistency in the implant-abutment-screw interfaces. Purpose : The purpose of this study was to evaluate the machining accuracy and consistency of implant/abutment/screw combinations on two randomly selected implants from each of four manufactures. Material and methods : In this study, screws were respectively used to secure a cemented abutment, to a hexlock implant fixture ; teflon coated titanium alloy screw(Torq-Tite) and titanium alloy screw in Steri--Oss system, gold-plated gold-palladium alloy screw(Gold-Tite) and titanium alloy screw in 3i system gild screw ana titanium screw in AVANA Dental Implant system, and titanium screws in Paragon System. The implants were perpendicularly mounted in polymethyl methacrylate autopolymerizing acrylic resin block(Orthodontic resin, Densply International Inc. USA) by use of dental surveyer. Each abutment screw was secured to the implant with recommended torque value using a digital torque controller. Each screw was again tightened after 10 minutes. All samples were cross sectioned with grinder-polisher unit(Omnilap 2000 SBT Inc) after embeded in liquid unsaturated polyester (Epovia, Cray Valley Inc) Results : There were the largest gaps in the neck areas of screws in hexagonal extension implants which were examined in this study. The leading edge of the abutment screw thread (superior surface) was in contact with the implant body thread, and the majority of the contacting surfaces were localized to the middle portion of the mating threads. Considerable variation in the contacting surfaces was noted in the samples evaluated. Amounts of contact in the abutment screw thread were larger for assemblies with Gold-Tite screw, gold alloy screw. Torq-Tite screw than those with titanium screws. The findings of intimate contact between the screw and screw seat were seen in all samples, regardless of manufacturers. However, microgap between the head and lateral neck surface of the screw and the abutment could be dectected in all samples. The findings of intimate contact between the platform of the implant and the bottom of the abutment were consistent in all samples, regardless of manufacturers. However, microgaps between the lateral surface of external hex of the fixture and the abutment could be dectected in all samples. Conclusion : Considerable variations in machining accuracy and consistency were noted in the samples and the implant-abutment-screw interfaces were incomplete. From the results of this study, further development of the system will be required, including improvements in pattern design.

• 대한치과보철학회지
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• 제42권2호
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• pp.192-209
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• 2004

Purpose : The purpose of this study was to evaluate the machining accuracy and consistency of implant/abutment/screw combination or internal connection type. Material and methods: In this study, each two randomly selected internal implant fixtures from ITI, 3i, Avana, Bicon, Friadent, Astra, and Paragon system were used. Each abutment was connected to the implant with 32Ncm torque value using a digital torque controller or tapping. All samples were cross-sectioned with grinder-polisher unit (Omnilap 2000 SBT Inc) after embeded in liquid unsaturated polyester (Epovia, Cray Valley Inc). Then optical microscopic and scanning electron microscopic(SEM) evaluations of the implant-abutment interfaces were conducted to assess quality of fit between the mating components. Results : 1) Generally, the geometry of the internal connection system provided for a precision fit of the implant/abutment into interface. 2) The most precision fit of the implant/abutment interface was provided in the case of Bicon System which has not screw. 3) The fit of the implant/abutment interface was usually good in the case of ITI, 3I and Avana system and the amount of fit of the implant/abutment interface was similar to each other. 4) The fit of the implant/abutment interface was usually good in the case of Friadent, Astra and Paragon system. The case of Astra system with the inclined contacting surface had the most Intimate contact among them. 5) Amount of intimate contact in the abutment screw thread to the mating fixture was larger in assembly with two-piece type which is separated screw from abutment such as Friadent, Astra and Paragon system than in that with one-piece type which is not seperated screw from abutment such as ITI, 3I and Avana system. 6) Amount of contact in the screw and the screw seat of abutment was larger in assembly of Friadent system than in asembly of Astra system of Paragon system. Conclusion: Although a little variation in machining accuracy and consistency was noted in the samples, important features of all internal connection systems were the deep, internal implant-abutment connections which provides intimate contact with the implant walls to resist micro-movement, resulting in a strong stable interface. From the results of this study, further research of the stress distribution according to the design of internal connection system will be required.

• 한국산업보건학회지
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• 제6권1호
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• pp.1-16
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• 1996

This study was conducted at an automobile assembly line located in Kyonggi-do, Korea from January 16 to February 28, 1995. The purposes of this study were to assess worker exposures to hand-arm vibration and the performance of gloves for reduction of vibration. The exposure to vibration was measured using to the ISO 5349(1986) method. Vibration acceleration and frequency spectra for each tool were determined on-line replicating actual working conditions and analyzed together with exposure time for evaluating individual worker exposure. Eight pneumatic hand tools, 60 workers exposured to hand-arm vibration, and three pairs of gloves were involved in this study. Results are summarized as follows. 1. Dominant frequencies of vibration for all tools(n=8) measured in this study ranged from 250 Hz to 800 Hz. 2. There was no significant correleration between dominant frequencies and free running speed (p>0.05). 3. Total predicted exposure times of using impact, hammer type did not exceed 40 minutes, but metal finish task, using grinder and sander exceeded 40 minutes. Total exposure time affected significantly the frequency-weighted, 4 hr equivalent acceleration. 4. Predicted prevalence and observed exposure period data were compared in workers(n=60), according to ISO 5349. In this results, 23(50.0 %) and 24(48.07 %) persons exceeded the mean latency periods for vibration-induced white finger(VWF) at 10 % (n=46) and 50 % (n=52) standards, respectively. On the basis of ISO equation, mean latent periods for VWF were 3.23, 4.72 years at 10 %, 50 % standards, respectively. 5. Reduction of vibration by gloves was evaluated. Since impact pneumatic tools produced low frequency vibrations, conventional gloves did not provide any protection. Gloves A and C amplify somewhat the signal at frequency below 400 Hz; the attenuation increases progressively by frequency to reach 18 dB ($7.94{\times}10^{-6}m/s^2$) at 1,000 Hz, slightly worsening Glove B did not provide any protection and made the situation slightly worse. However, since they make the hands warm, the occurrence of vibration-induced white fingers may be reduced.

• Journal of Biosystems Engineering
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• 제39권2호
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• pp.122-133
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• 2014

Purpose: This study was to develop an effective process for fabricating biocompatible calcium phosphate powders (CPPs) using horse bones, and to investigate the characteristics of them. Methods: The characteristics of horse bone powders (HBPs) were investigated according to the different osseous tissue types (compact bone and cancellous bone), bone types (spine and tibia), pretreatment methods (cold water, $H_2O_2$, and hot water), sintering time (4, 8 and 12h), and sintering temperature (600, 900, 1100 and $1300^{\circ}C$). In addition, the grinding methods were compared based on the wet grinding (ball mill) and dry grinding (blade grinder) method to make it as powders. Finally, their cytotoxicity and cell viability were checked. Results: Regardless of the types of osseous tissues and bones, HBPs were well fabricated as biocompatible CPPs. It was also found that the pretreatment methods did not influence on the resultants, showing well-fabricated HBPs. Considering the processing time, the hot water method was the most suitable compared to other pretreatment methods. Further, 12h-sintering time was sufficient to remove residual organic compounds. The sintering temperatures greatly affected the properties of bone powders fabricated. The x-ray diffraction (XRD) peak of horse bone sintered at $600^{\circ}C$ was most closed to that of hydroxyapatite (HA). Our bioactivity study demonstrated that the HBPs fabricated by sintering horse bones at $1300^{\circ}C$ showed the best performance in terms of cell viability whereas the HBPs $1100^{\circ}C$ showed the cytotoxicity. Conclusions: Using various types of horse bone tissues, biocompatible CPPs were successfully developed. We conclude that the HBPs may have a great potential as biomaterials for various biological applications including bone tissue engineering.