• Journal of Sericultural and Entomological Science
• /
• v.25 no.2
• /
• pp.44-50
• /
• 1984

The effects of sodium pyrophosphate, sodium tripolyphosposphate and ethylene diamine tetraacetic acid as a degumming aid reagent were investigated under the conditions of underground water and dimineralized water for the scouring water sources. The changes of water qualities by adding the condensed sodium phosphates and the physical properties of scoured silk fabric were examined, respectively. 1. The water hardness of underground water was decreased by adding the condensed sodium phosphates and it was further reduced according to the increasing temperature. The water hardness reducing power of sodium pyrophosphate was a little stronger than that of sodium tripolyphosphate. 2. The sodium silicate as an alkaline reagant for scouring decreased the water hardness, but the sodium carbonate increased it in the underground water. 3. The pH value of 0.4% soap and 0.25% sodium silicate mixed solution after boiling was. 9.80, but it was leveled upto 9.90 by adding 0.05% sodium pyrophosphate and upto 9.95 by 0.02% ehtylene diamine tetraacetic acid, respectively. 4. The masking action of Fe$\^$3+/ ions dissolved in the scouring water was more remarkable by ethylene diamine tetraacetic acid than by the condensed sodium phosphates. Of the condensations, sodium tripolyphosphate was more effective than sodium pyrophosphate in the action. 5. Genrally, the dimineralized water scouring increased the boil-off ratio with reducing the flexural rigidity of fabric which was negatively related with the favorablility of hand-touch more than the underground one did. 6. Under the underground water scouring, the addition of ethylene diamine tetraacetic acid increased the boil-of ratio and compressive elasticity of fabric with reducing the flexural rigidity more than that of the condensed sodium phosphates did. 7 The additions of sodium tripolyphosphate and ethylene diamine tetraacetic acid reduced the flexural rigidity of fabric with raising the boil-off ratio even in the dimineralized water scouring, but there was no sifnificant difference between both of them.

• Journal of Adhesion and Interface
• /
• v.16 no.3
• /
• pp.101-107
• /
• 2015

Epoxy resin toughening agents such as core/shell nanoparticles, CTBN epoxy, polyester polyols, and polyurethane have been widely used in order to compensate for the brittleness and improve the impact resistance of the epoxy resin. In this work, a few tougheners mentioned above were individually added into adhesive compositions to observe the effects of physical and mechanical properties. Both flexural strength and flexural modulus were measured with UTM while impact strength was analyzed with Izod impact tester. The obtained results showed that the addition of toughening agents afforded positive performance in terms of flexibility and impact resistance of the cured epoxy resin. Furthermore, DMA experiments suggested that the trends of storage modulus data of each epoxy resin composition coincided with the trends of flexural modulus data. FE-SEM images showed that toughening agents formed circled-shape particles when it was cured in epoxy resin composition at high temperature by phase separation. The existence of particles in the cured samples explains why epoxy resin with toughener has higher impact resistance.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2017.04a
• /
• pp.83-83
• /
• 2017

국내에 유통되는 제초날은 대부분 금속으로 제작되며, 금속 날의 대부분 탄소공구강(SK-3~5)으로 제작되고, 날 수 및 날 형태에 따라 2도 날, 3도 날, 4도 날, 8도 날, 톱날로 구분된다. 대부분 평지 제초작업에 사용되고, 고랑 제초 작업에 알맞은 제초날의 없어 고랑 제초 작업의 효율이 떨어진다. 본 연구는 굴곡이 있는 밭의 고랑 제초 작업에 효율적인 원형 제초날을 설계 하고자 한다. 밭작물의 제초작업은 굴곡이 있는 이랑과 고랑 사이의 잡초를 제거해야 하기 때문에 평지의 잡초를 제거하는 제초날로는 제초작업이 거의 불가능하다. 따라서 고랑 형상에 맞는 원형 제초날을 설계 하였으며, 회전 균형 및 무게의 균일성 설계가 쉬운 뼈대형 원형 제초날을 설계한 후 데이터를 이용하여 원형 제초날을 설계하였다. 또한 고랑의 잡초 뿌리부분을 제거하기 위해 원형 제초날에 돌출부를 추가하는 방법으로 설계하였다. 제초날은 밭작물 고랑폭을 기준으로 하여 높이는 85mm 직경은 300mm로 설계하였으며, 제초날 설계시 원형 제초날은 뼈대형 원형 제초날과 같이 고랑폭을 기준으로 하여 높이 및 직경을 뼈대형 원형 제초날과 동일한 치수로 설계하였다. 원형 제초날 설계에서 돌출부를 볼트 결착방식으로 설계하였으며, 회전중 돌출부의 파손 혹은 이탈을 방지하기 위하여 직경 5mm이상의 볼트 결착이 필요하였다. 볼트 결착방식은 제초날 조립후 제초날 회전시 고랑의 잡초를 효과적으로 제거하기 위한 작업공간 확보가 어려울 것으로 판단되었다. 따라서 제초날 원형부에 돌출부를 절단 절곡하는 방식으로 돌출부를 재설계하였으며, 돌출부 길이는 안쪽 부분 15mm, 바깥 부분 20mm로 설계하고, 돌출부 회전반경은 안쪽 날 20mm, 바깥 날 10mm로 설계하였다. 일반적인 제초날 과 달리 원형 제초날을 개발하기 위해서 회전균형과 안전이 제초날 설계에 중요한 요인이 된다. 뼈대형 제초날을 통하여 제초날의 균형 데이터를 분석하였고 이를 바탕으로 원형 제초날을 설계하였다. 또한 발란싱 머신을 이용한 회전시험에서 unbalance 정도가 3,600rpm에서 4.51/47.1deg로 나타나 제초기에 적용 가능할 것으로 판단되었다.

• The korean journal of orthodontics
• /
• v.28 no.6 s.71
• /
• pp.905-914
• /
• 1998

The goals of this study were to present presurgical naso-alveolar molding (PNAM) appliance in unilateral cleft lip and palate treatment and to evaluate the effects of PNAM appliance on alveolar molding. Samples were consisted of 4 unilateral cleft lip and palate infants (3 males and 1 female, mean age=23.2 days after birth) who were treated with PNAM appliances in Department of Orthodontics, Seoul National University Dental Hospital. Average alveolar cleft gap between the greater and lesser segment was 8.27mm and average duration of alveolar molding treatment was 9.7 weeks. These patients' models were obtained at initial visit (T1) and alter successful alveolar molding (T2). Seven linear and five angular variables were measured by using photometry and digital caliper. All statistical analyses were performed by SPSS win ver. 7.5 program. Paired t-test was used to compare the mean values. 1. The posterior part of alveolar segments are the stable structures during alveolar molding treatment period in infants. 2. Forward growth of the greater segment may be hindered by the action of alveolar molding. 3. The closure of cleft gap during alveolar molding were usually due to inward and backward bending of the anterior part of the greater segment and outward bending of the whole lesser segment.

• Journal of dental hygiene science
• /
• v.9 no.4
• /
• pp.405-412
• /
• 2009

The purpose of this study investigated the effect of Au coating on adhesion between porcelain matrix and metal substructure interface. Titanium, Ni-Cr alloy and Co-Cr alloy are well known as proper metal for the dental restorations. The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. However, adhesion between dental alloys and porcelain is related to diffusion of oxygen during ceramic firing. The excessive oxidized layers make hard adhesion between dental alloy and ceramic. Ni-Cr and Co-Cr specimens were divided into test and a control group and Titanium specimens were divided into three test groups and a control group. Each group had 20 specimens. The adhesion characteristics of porcelain and metal with Au coating layer and without Au coating layer were observed with scanning electron microscopy(SEM). The adhesion was evaluated by a biaxial flexure test and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that Au coating layer is effective barrier to diffuse oxide layer completely protect non-precious alloys from oxidation during the porcelain firing. The SEM photomicrographs of cross-section specimens showed a smooth interface between Au coating layer and metals and porcelain which suggested proper chemical bonding, and no gap, porosity were observed. The mode of failure was mainly adhesive for Ti tested specimens, but mixed failures with adhesive and cohesive were observed in Ni-Cr and Co-Cr specimens. The adhesion between non-precious metals and porcelain would not be improved by Au coating agent. However, It is suggested that the continuous study is required further investigation and development.

• Clean Technology
• /
• v.27 no.1
• /
• pp.24-32
• /
• 2021

Unburned carbon (UC) was successfully separated from fly ash by up to 85.8% in weight via froth flotation using soybean oil as a collector. An 18 wt% yield of microceramics (CM) could be achieved by employing a hydro cyclone separator located immediately after the flotation equipment. UC and CM were tested as alternatives to weight-adding material and polymer (especially polypropylene in this study) filler, respectively. Large particles of UC were broken down into smaller ones via ball milling to have an average particle diameter of 10.2 ㎛. When crushed UC was used as an alternative to clay as a rubber weight-adding material, a somewhat lower tensile strength and elongation rate than the allowed values were unfortunately obtained. In order to satisfy the standard limits, further treatment of UC is required to enhance surface energy for more intimate bonding with rubber. CM was observed in spherical forms with an average diameter of 5 ㎛. The surface of the CM particles was modified with phenol, polyol, stearic acid, and oleic acid so that the surface modified CM could be used as a polypropylene-filling agent. The flowability was good, but due to the lack of coupling forces with polypropylene, successful impact strength and flexural strength could not be obtained. However, when mixing the surface-modified CM with 1% silane by weight, a drastic increase in both the impact strength and flexural strength were obtained.

• Korean Journal of Applied Biomechanics
• /
• v.19 no.1
• /
• pp.107-115
• /
• 2009

The purpose of this study were to investigate the effects of muscle, balance and walking training on muscle, balance and gait kinematics in children with Down syndrome. Nine children ($9{\sim}12$ years old) with Down syndrome participated in this study. The participant with Down syndrome participated in muscle, balance and walking training for 12 weeks, three times a week Kinematic variables of gait were measured 3-dimentional motion capture system. The results indicated that the pelvis rotation decreased, the knee and hip flexion increased, decreased leg sway during the swing phase, the cadence increased, and the stride length decreased after the muscle, balance and walking training. In conclusion, Down syndrome's gait kinematic variables improved after the muscle, balance and walking training.

• Composites Research
• /
• v.24 no.6
• /
• pp.7-11
• /
• 2011

Polyurethane oligomers (PUOs) such as UA8297, UP127 and EB8200 were utilized to enhance the anti-bullet property of Dyneema$^{(R)}$/vinylester composites. First, prepregs of PUO and vinylester (XSR10) were prepared via spray coating on Dyneema$^{(R)}$ fabric at 21 % resin content (by volume). In addition, spray coating and film lamination were also carried out with a mixture of XSR10/PUO for selected PUOs. Next, the prepregs were dried at RT for 1-2 h and then at $100^{\circ}C$ for 30 min to remove the solvent and to provide partial cure when necessary. The prepregs were stacked in 24 layers and cured at $120^{\circ}C$ for 5 min under the contact pressure and for additional 25 min at 150 $kg/cm^2$. Finally, the anti-bullet properties of composite samples were evaluated by measuring $V_{50}$ with simulated fragment projectile (SFP, 17 gr). The results showed a 6.5 and 9.0 % increase of $V_{50}$ with UP127 and EB8200, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.7
• /
• pp.2468-2474
• /
• 2010

The purpose of this study was to investigate the effects of taping therapy and passive range of motion exercises for the elderly aged 65 above with shoulder pain and limited of range of motion. This study was a nonequivalent control group pretest-posttest design. Data were collected about shoulder pain, range of motion, hand dexterity from 40 of elderly(exp.:20, con.:20) in B city from August to September, 2009. Collected data were analyzed using SPSS Win 12.0. Shoulder pain was significantly decreased. Range of motion which was flexion, extension, abduction, horizontal abduction. and hand dexterity were significantly increased in the taping group and PROM group. Shoulder pain and hand dextrity was non significantly between taping group and PROM group. Range of motion which was extension more increased taping group than PROM group. It was proven that taping therapy and PROM was effective for shoulder pain, articular range of motion and hand dexterity.

• Journal of the Korea Convergence Society
• /
• v.12 no.12
• /
• pp.411-418
• /
• 2021

The purpose of this study was to find out the effects of isomatric and isotonic exercise on the muscle function and cytokine which will prevent recurrence of breast cancer patients. A subjects were thirteen breast cancer patients and they were randomly assigned either isometric exercise group(n=10), isotonic exercises group(n=10) or a daily base care control group(n=10). Resistance exercise group did a exercise program with 60~70%RM for 60min, 3days per week during 8week. There were significantly difference between groups which were showing a increasing flexion, abduction, external rotation, IL-6 and IL-10 in isotonic exercise.