• Physical Therapy Korea
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• v.19 no.4
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• pp.24-31
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• 2012

The aim of this study was to investigate the effectiveness of self-stretching exercises for iliotibial band (ITB) (Side-lying; right hip and knee were flexed to support the pelvis while left hip was extended and adducted, Standing A; side-bending of the trunk on standing with crossed leg, Standing B; same as Standing A, except the hands were clasped overhead and shifted right side, and Standing C; same as Standing B, except moving the arms diagonally downward) to help determine the most effective self-stretching method to stretch ITB. Twenty-one healthy subjects who do not have ITB shortness from Yonsei University (14 men and 7 women) between the ages of 18 to 28 years voluntarily participated. Ultrasound was performed to measure the thickness of the ITB between the long axis of the ITB and the level parallel to the lateral femoral epicondyle during four self-stretching exercises. All data were found to approximate a normal distribution. We used a one-way repeated-measures analysis of variance (ANOVA) to compare the thickness of the ITB among all self-stretching exercises. The level of significance was set at ${\alpha}$=.05. The ANOVA was followed by Bonferroni's correction. The overall mean of ITB thickness was $1.14{\pm}.4$ mm (${\pm}$ standard deviation) in resting status. The change in the ITB thickness in percentages between the tested position of each self-stretching exercises and resting status was significant (p<.05) (Side-lying $26.62{\pm}10.18%$ with 95% confidence interval [CI]=21.99~31.25%; Standing A $29.46{\pm}16.19%$ with 95% CI=22.09~36.84%; Standing B $44.06{\pm}14.82%$ with 95% CI=37.31~50.81%; Standing C $53.76{\pm}12.1%$ with 95% CI=48.25~59.29%). Results indicated significant differences among four self-stretching exercises except Side-lying versus Standing A (p<.01). Based on these findings, the Standing C self-stretching exercise was the most effective in stretching the ITB thickness among four types of ITB self-stretching exercises. Additionally, the Side-lying self-stretching exercise using gravity to stretch the ITB is recommended as a low-load (low-intensity), long-duration stretch.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.84-95
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• 2001

Titanium is widely used in dentistry for its low density, high strength, fatigue resistance, corrosion resistance, and biocompatibility. But it has a tendency of surface damage under circumstance of friction and impact for its low hardness of the surface. Coating is one of methods fir increasing surface hardness. Its effect is to improve surface physical characteristics without change of titanium. Diamond-like carbon and titanium nitride are known for its high hardness of the surface. So that this study was aimed at the wear test and the cytotoxicity test of the commercially pure titanium and Ti-6Al-4V alloy which were deposited by diamond-like carbon film or titanium nitride film to acertain improvement of the surface hardness and the biocompatibility. A disk (25mm diameter, 2mm thickness) was made of commercially pure titanium and Ti-6Al-4V alloy and these substrates were deposited by diamond-like carbon film or titanium nitride film. Diamond-like carbon film was deposited by the method of radiofrequency plasma assisted chemical vapor deposition and titanium nitride film was deposited by the method of reactive arc ion plating. Then these substrates were tested about wear characteristics by the pin-on-disk type wear tester in which ruby ball was used as a wear causer under the load of 32N, The fracture cycles were measured by rotating the substrates until their films were fractured. The wear volume was measured after 150 cycles and 3,000 cycles using surface profiler. The cytotoxicity test was peformed by the method of the MTT assay. The results were as follows : 1. In the results of the wear volume test, commercially pure titanium and titanium alloy which were coated by diamond-like carbon film or titanium nitride aim had higher resistance against wear than the substrates which were not coated by any films (P<0.05). 2. In the results of the fracture cycle test and the wear volume test, diamond-like carbon film had higher resistance against wear than titanium nitride film (P<0.05). 3. In both coatings of diamond-like carbon aim and titanium nitride film, Ti-6Al-4V alloy had higher resistance against wear than commercially pure titanium (P<0.05) 4. In the results of the cytotoxicity test, diamond-like carbon film and titanium nitride film had little cytotoxicity as like commercially pure titanium or Ti-6Al-4V alloy (P>0.05).

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.181-188
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• 2015

The non-contact permanent magnet gear has advantages of high efficiency and improved reliability. It has other advantages of no mechanical friction loss, very little noise and vibration, and no need for lubricant. With these advantages, the non-contact permanent magnet gear that solves the physical contact problem of the mechanical gear has drawn attention. Due to this unique non-contact characteristic, the non-contact permanent magnet gear which is capable of non-contact torque transmission has replaced mechanical gear. The mechanical gears which is in many fields of the modern industry, is used mostly for power transmitting mechanical devices. However, it also has the problem of a low torque density, which requires improvement. In this paper, a novel pole piece shape is proposed in order to improve the problem of low torque density of the non-contact permanent magnet gear. The experiment data required for predicting the relationships among them are obtained using finiteelement Operating method based on two-dimensional (2-D) numerical analysis. Therefore, this paper derived an optimal model for thenon-contact permanent magnet gear with the novel pole piece using the Box-Behnken design, and the validity of the optimal design of the proposed pole piece shape through variance analysis and regression analysis demonstrated. In this paper, we performed the thransfer torque analysis in order to improve the torque density and power density, we have performed on optimal design of proposed pole piece shape using box-behnken.

• Journal of Appropriate Technology
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• v.7 no.1
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• pp.51-58
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• 2021

This study proposes the design and implementation of a low-cost emergency ventilator which can be helpful during the COVID-19 pandemic where the supply of automatic ventilators is not smooth compared with the urgent demand worldwide. Easy implementation and lower price were made possible by using AMBU-bag and off-the-shelf embedded micro-controller board. Moreover, while 3D printing is used by companies and experts around the world to build prototype hardware, materials which are readily available from surrounding environments so that people in countries where it is difficult to access many advanced technologies could manufacture the system. The design features AMBU-bag automation, not use 3D printing, and it can contrl speed. By allowing speed control, ventilation can be performed according to the conditions of the patient being used. A complementary point in the study is that it is difficult to fix the start point of the wiper motor used first. A method for complementing this is a method for replacing the brush DC motor with a position feedback function. Secondly, the AMBU-bag may wear out in the long-term process of compressing the AMBU-bag because the arm and the fixing frame are made of wood. To complement this, the part of fixing frame and arm parts that the AMBU-bag touches need to be wrapped in a material such as silicon to minimize friction.

• The korean journal of orthodontics
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• v.41 no.6
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• pp.399-410
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• 2011

Objective: The purpose of this study was to evaluate the difference in frictional resistance among metal, ceramic, self-ligation brackets and coated or non-coated Ni-Ti archwires at various bracket-archwire angulations during the sliding movement of an orthodontic archwire, using an orthodontic sliding simulation device. Methods: Four types of bracket (Micro-arch Perpect Clear2 Clippy-C and Damon3 and 5 types of orthodontic archwire (0.014", 0.016", and 0.016" ${\times}$ 0.022" inch coated Ni-Ti, and 0.016" and 0.016" ${\times}$ 0.022" inch Ni-Ti) were used. Further, the bracket- archwire angles were set at 4 different angulations: $0^{\circ}$, $3^{\circ}$, $6^{\circ}$, and $9^{\circ}$. Results: The frictions from all the experimental groups were found to be significantly increased in order of self-ligation brackets, Micro-arch and Perpect Clear2 ($p$ < 0.001). The presence of a coat had no effect on the friction of the same sized archwires at $0^{\circ}$ and $3^{\circ}$ bracket-archwire angles ($p$ < 0.001). Coated archwires had significantly higher frictions than the same sized non-coated archwires at $6^{\circ}$ and $9^{\circ}$ bracket-archwire angles ($p$ < 0.001). The frictions increased significantly as the bracket-archwire angles were increased ($p$ < 0.001). Conclusions: The use of self-ligation brackets will be beneficial in clinical situations where a low frictional force is required. Further, in cases where crowding is not severe, the use of coated archwires should not cause problems. However, more additional explanation is required considering the fact that the damage of coated archwire and exposure of the metal portion in case of binding and notching and the effects of saliva were not taken into account.

• The Journal of Engineering Geology
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• v.16 no.4 s.50
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• pp.359-371
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• 2006

In this study, the soil characteristics are analyzed using the result of various soil tests as an object of the soil layer of natural slopes in landslides areas composed with gneiss, granite, and the tertiary sedimentary rock. To investigate the soil characteristics according to landslide and non landslide areas, soils are sampled from Jangheung, Sangju and Pohang. The landslides at three areas are occurred due to heavy rainfall in same time. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. On the basis of the landslide data and the result of soil test, the soil characteristics at the landslide area and the differentiation between landslide area and non landslide area are analyzed. However soil characteristics have a little differentiation to geological condition, the uniformity coefficient and the coefficient of gradation of soils at the landslide area is larger than those of soils at the non landslide area. Also, the proportion of fine particle of soils at the landslide area is higher. The plastic limit of soils sampled from the granite and the sedimentary rock regions is larger than that sampled from the gneiss region. However the liquid limit is irrelevant to the geological condition. Also, the consistency of soils at the landslide area is smaller. The natural moisture content of soils in the sedimentary rock regions is larger than that of the granite and gneiss. It is mainly influenced by mineral composition, soil layer structure, weathering condition, and so on. The soils sampled from landslide area have higher porosity and lower density than those from non landslide area. It means that the soils of landslide area have poor particle size distribution and loose density. Therefore, the terrain slope with poor distribution and loose density is vulnerable to occur in landslides. Also, landslides are occurred in the terrain slope with high permeability. The permeability is mainly influenced by the soil characteristics such as particle size distribution, porosity, particle structure, and the geological origins such as weathering, sedimentary environment. Meanwhile, the shear strength of soils is little difference according to the geological condition. But, the internal friction angle of soils sampled from the landslide area is lower than that of soils from the non landslide area. Therefore, the terrain slope with low internal friction angle is more vulnerable to the landslide.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.127-136
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• 2015

To evaluate the effects of limestone powder and silica fume on the properties of high-strength high-volume ground granulated blast-furnace slag (GGBFS) blended cement concrete, this study investigated the rheology, strength development, hydration and pozzolanic reaction characteristics, porosity and pore size distribution of high-strength mortars with the water-to-binder ratio of 20, 50 to 80% GGBFS, up to 20% limestone powder, and up to 10% silica fume. According to test results, compared with the Portland cement mixture, the high-volume GGBFS mixture had much higher flow due to the low surface friction of GGBFS particles and higher strength in the early age due to the accelerated cement hydration by increase of free water; however, because of too low water-to-binder ratio and cement content, and lack of calcium hydroxide content, the pozzolanic reactio cannot be activated and the long-term strength development was limited. Limestone powder did not affect the flowability, and also accelerate the early cement hydration. However, because its effect on the acceleration of cement hydration is not greater than that of GGBFS, and it does not have hydraulic reactivity unlikely to GGBFS, compressive strength was reduced proportional to the replacement ratio of limestone powder. Also, silica fume and very fine GGBFS lowered flow and strength by absorbing more free water required for cement hydration. Capillary porosities of GGBFS blended mortars were smaller than that of OPC mortar, but the effect of limestone powder on porosity was not noticeable, and silica fume increased porosity due to low degree of hydration. Nevertheless, it is confirmed that the addition of GGBFS and silica fume increases fine pores.

• Asian Journal of Atmospheric Environment
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• v.6 no.2
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• pp.73-82
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• 2012

This study was aimed to thoroughly estimate the characteristics of indoor particulate matter (PM) collected on subway platforms by the cooperative approach of semi-bulk and single particle analyses. The size-resolved PM and its number concentration were measured on the platform in a heavily traveled subway station in Fukuoka, Japan. Particle Induced X-ray Emission (PIXE) and micro-PIXE techniques were applied to the chemical analyses of semi-bulk and single particle, respectively. There was the close resemblance of timely fluctuation between PM number concentration and train service on the third basement floor (B3F) platform compared to the second basement floor (B2F) and its maximum level was marked in rush hour. Higher number counts in large particles ($>1{\mu}m$) and lower number counts in fine particles ($<1{\mu}m$) were shown on the platform compared to an above ground. PM2.5 accounted for 58.2% and 38.2 % of TSP on B3F and on B2F, respectively. The elements that were ranked at high concentration in size-resolved semi-bulk PM were Fe, Si, Ca, S, and Na. The major elements tending to have more elevated levels on B3F than B2F were Fe (4.4 times), Ca (17.3 times), and Si (46.4 times). Although concentrations were very low, Cr ($11.9ng\;m^{-3}$ on B3F, $2.4ng\;m^{-3}$ on B2F), Mn ($3.4ng\;m^{-3}$ on B3F, $0.9ng\;m^{-3}$ on B2F), and Pb ($0.6ng\;m^{-3}$ on B3F, $1.6ng\;m^{-3}$ on B2F) were detected from PM2.5. Individual PM was nearly all enriched in Fe with Si and Ca. Classifying and source profiling of the individual particles by elemental maps and particle morphology were tried and particles were presumably divided into four groups (i.e., train/rail friction, train-rail sparking, ballast/abrasive, and cement).

• Journal of Korean Academy of Nursing
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• v.31 no.1
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• pp.94-106
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• 2001

The purpose of this study was to verify the use of Seo's Elderly Stress Scale (SESS), which was developed in 1996. Through the modified tool, it is possible to examine the stress of Korean elders and to contribute to the welfare of them. The subjects were 350 elders over 65 years old who live in Seoul, Kwang-Ju, Yang-Ju Gun Kyung-ki Do, Ui-Jong Bu, and Young-Am Kun, Jeun-Ra Nam Do. the data of 331 elders (94%) were analyzed. Data were collected between January and March in 1996 and analyzed using the SPSS Win 8.0. The result are as follows: 1. Items with low correlation with the total items were removed. So 27 items were removed and 37 items remained. This 37 items were death in the family and/or close friends, family member's behavior not meeting expectations, marriage of daughter, marriage of son, friction with daughter- in-law, argument among children, children refuse to live with parent, children leaving home, sex injury or accident, in frequest visits from children and grandchildren, providing care for your daughter or daughter-in-law post-partum, decrease in decision making and authority in home, Lunar new year and the harvest featival, house sitting, working in the house, performing a sacrificial rite, missed birthday, not living with the eldest son, decreased eyesight, decreased strength, decreased memory, sleep pattern changes, thoughts about death, loneliness, decreased hearing, change of dental condition, change in your diet or eating style, difficulty in self care, moving because of disease or aging, argument with friend or neighbour, travel, dealing with the procedure of heritage, loss of money or property, not enough pocket money, hearing on elderly neglect in television or radio, hope of going home and ignorant from others. 2. Overlapped items were discussed by colleagues and were modified. 'marriage of daughter' and 'marriage of son' were modified in 'marriage of children'. 'self injury or accidents' and 'family accidents' were modified in to self or family accidents. 3. Factor analysis was done in order to identify validity and three factors were obtained from the result. The first factor familial relation area, included 17 items. The second factor, physical area, included 9 items. The third factor, psycho-socio-economic area, included 9 items. Cronbach coefficient alpha for the 35 items was .923. 4. Pearson's correlation was .704 between SESS and SOS (Symptoms of Stress) in order to confirm construct validity. Based on the result, the following is suggested; 1. The modified SESS needs to be reverified with elder. 2. Korean elder's health promotion can be made by development of stress intervention which was accurately measured with SESS.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.2
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• pp.169-177
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• 2016

Sliding slab track system, which consists of low friction sliding layer between track slab and bridge deck, is recently devised to reduce track-bridge interaction effect of continuously welded rail(CWR) without applying special devices such as rail expansion joint(REJ). In this study, a series of track-bridge interaction analyses of a long-span bridge with sliding slab track and REJ are performed respectively and the results are compared. The bridge model includes PSC box girder bridge with 9 continuous spans, and steel-concrete composite girder bridge with 2 continuous spans. The total length of the bridge model is 1,205m, and the maximum spacing between the two fixed supports is 825m. Analyses results showed that the sliding slab track system is highly effective on interaction reduction since lower rail additional axial stress is resulted than REJ application. Additionally, horizontal reaction forces in fixed supports were also reduced compared to the results of REJ application. However, higher slab axial forces were developed in the sliding slab track due to the temperature load. Therefore, track slab section of the sliding slab track system should be carefully designed against slab axial forces.