• Journal of the Korean Society of Clothing and Textiles
• /
• v.19 no.5
• /
• pp.826-841
• /
• 1995

This study is concerned with the functional utility of movement in sleeve from an ergonomic viewpoint. Experiments were carried out which include 43 upper extremity segments, 21 motions and 35 female subjects. The major conclusions of the study are. 1. The expansion rate of upper extremity was higher in length than in circumference mesurements. The amounts of expansion were, especially high (more than 60mm) for inner arm length, axillary arm circumference, and outer arm length. Therefore, a lot of ease is necessary for these parts. On the other hand, armhole circumference, forearm circumference, and wrist circumference had low rates of expansion. The sleeve cap length was also contracted in all motions. 2. The expansion rate and the range of expansion and contraction were higher in the upper arm than in the forearm. The main points of expansion were the axillary and elbow parts. The segment of maximum expansi (rate of 44.8%) was Iii of axillary parts. As the body surface expands mainly in some segments, it is desirable to allow ease to the main segments of expansion. 3. In a basic sleeve, necessary ease was lacking in the measurements for outer arm length and axillary arm circumference, while it was too large in armhole circumference, forearm circumference, wrist circumference, and sleeve cap length. Therefore, a basic sleeve is inadequate as a functional sleeve for hard work in point of functional utility of movement. Wider application of these findings would lead to an improvement in the comfort of workers.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2005.10a
• /
• pp.321-333
• /
• 2005

With the limited frequency spectrum and an increasing demand for cellular communication services, the problem of channel assignment becomes increasingly important. However, finding a conflict free channel assignment with the minimum channel span is NP hard. As demand for services has expanded in the cellular segment, sever innovations have been made in order to increase the utilization of bandwidth. The innovations are cellular concept, dynamic channel assignment and hierarchical network design. Hierarchical network design holds the public eye because of increasing demand and quality of service to mobile users. We consider the frequency assignment problem and the base station placement simultaneously. Our model takes the candidate locations emanating from this process and the cost of assigning a frequency, operating and maintaining equipment as an input. In addition, we know the avenue and demand as an assumption. We propose the network about the profit maximization. This study can apply to GSM(Global System for Mobile Communication) which has 70% portion in the world. Hierarchical network design using GA(Genetic Algorithm) is the first three-tier (Macro, Micro, Pico) model, We increase the reality through applying to EMC (Electromagnetic Compatibility Constraints). Computational experiments on 72 problem instances which have 15${\sim}$40 candidate locations demonstrate the computational viability of our procedure. The result of experiments increases the reality and covers more than 90% of the demand.

• Macromolecular Research
• /
• v.13 no.3
• /
• pp.212-217
• /
• 2005

The pyrolysis kinetics of polyurethanes synthesized from polycaprolactone diol (PCL) and diisocyanate (HDI, $H_{12}MDI$) using catalysts such as dibutyltin dilaurate (DBTDL) were studied by a thermogravimetric (TG) technique, which involved heating the sample at the rates of 10, 20 and $30^{\circ}C$/min. The effect of the kind of diisocyanate and the hard segment contents on the activation energy and reaction order were examined at conversions ranging from 1 to $100\%$. The activation energies at first increased slowly with increasing conversion. Also, differential scanning calorimetry (DSC) was used to investigate the structural differences in each polyurethane. DSC can reveal the melting behavior, in terms of the glass transition temperature ($T_g$), which is known to vary as a function of the stoichiometry and processing conditions.

• Polymer(Korea)
• /
• v.29 no.4
• /
• pp.344-349
• /
• 2005

Polyurethanes(PUs) were synthesized by reaction of isophorone diisocyanate, acetylbutyl citrate, and 3 types of polycaprolactone diol. Their structures were confirmed by FT-IR and NMR spectrometer. And, their thermal and mechanical properties were measured by TGA ud UTM. The effective network chain lengths ($\bar{M}_c$), measured by compressive modulus apparatus, were about $8000\~24000$ g/mol. As crosslinking density and amount of hard segment increased, tensile strength increased and elongation decreased. As the crosslinking density of PUs increased, thermal property inproved. When the ratio of NCO/OH is 1.1, maximum crosslinking density was achieved.

• Elastomers and Composites
• /
• v.45 no.3
• /
• pp.156-164
• /
• 2010

Thermoplastic elastomers (TPEs) exhibit both elastomeric behaviors at used temperature range and melt processibility. Polyamide based thermoplastic elastomers (TPAEs) are segmented block copolymers with hard blocks consisting of polyamide segments, while the soft blocks usually consist of flexible segments having a low glass transition temperature. The TPAE is one of the engineering TPEs possessing high thermal stability, excellent mechanical performances, chemical resistance and excellent processibility. And they showed wide range of physical and functional properties depending upon the structure of each segment and their relative contents and the hybridization with various inorganic particles. In this review, synthesis, properties, and possible applications of TPAEs are summarized.

• Phonetics and Speech Sciences
• /
• v.3 no.1
• /
• pp.23-34
• /
• 2011

Many Korean children have difficulty learning English vowels. The gestures inside the oral and pharyngeal cavities are hard to control when they cannot see the gestures and the target vowel system is quite different from that of Korean. This study attempts to collect children's acoustic data of twelve English vowels published by Hillenbrand et al. (1995) online and to examine the acoustic features of English vowels for phoneticians and English teachers. The author used Praat to obtain the data systematically at six equidistant timepoints over the vowel segment avoiding any obvious errors. Results show inherent acoustic properties for vowels from the children's distribution of vowel duration, f0 and intensity values. Second, children's gestures for each vowel coincide with the regression analysis of all formant values at different timepoints regardless of the vocal fold and tract difference. Third, locus points appear higher than those of American males and females. Their gestures along the timepoints display almost similar patterns. From the results the author concludes that vowel formant trajectories provide useful and important information on dynamic articulatory gestures, which may be applicable to Korean children's education and correction of English vowels. Further studies on the developmental study of vowel formants and pitch values are desirable.

• The Journal of Fisheries Business Administration
• /
• v.49 no.4
• /
• pp.53-68
• /
• 2018

The industrial structure of Chuja Island is mainly occupied by fisheries. Since the fisheries resources have been depleted and the marine environment has been changed, the fishery industry has been hard to survive. It is the time when residents are looking for a breakthrough in the tourism industry. Market segmentation is a valuable tool in the establishment of marketing strategies. Segmentation of tourists by the same desire and motivation is an essential factor in identifying the characteristics of tourists. The research on market segmentation of tourism sector focuses mainly on demographic subdivision, psychological subdivision, and behavioral subdivision, so it is urgent to study geographical market segmentation. The purpose of this study is to present data that can be used to establish a marketing strategy for tourism promotion in Chuja Island by analyzing the tourism activities via subdivision market according to demographic characteristics, tourism behavior characteristics, and tourism motivation after grasping the geographical segment of tourists through empirical analysis. In this study, 285 valid samples were analyzed by frequency analysis, ${\chi}^2$ test, cluster analysis and ANOVA test.

• Elastomers and Composites
• /
• v.54 no.3
• /
• pp.225-231
• /
• 2019

Bio-based polyester polyol was synthesized via esterification between azelaic acid and isosorbide. After esterification, bio-based polyurethanes were synthesized using polyester polyol, 1,3-propanediol as the chain extender, and 4,4'-diphenylmethane diisocyanate, in mixing ratios of 1:1:1.5, 1:1:1.8, 1:1:2, and 1:1:2.3. The bio TPU (Thermoplastic Polyurethane) samples were characterized by using FT-IR (Fourier Transform Infrared Spectroscopy), TGA (Thermal Gravimetric Analysis), DSC (Differential Scanning Calorimetry), and GPC (Gel Permeation Chromatography). The mechanical properties (tensile stress and hardness) were obtained by using UTM, a Shore A tester, and a Taber abrasion tester. The viscoelastic properties were tested by an Rubber Processing Analyzer in dynamic strain sweep and dynamic frequency test modes. The chemical resistance was tested with methanol by using the swelling test method. Based on these results, the bio TPU synthesized with the ratio of 1:1:2.3, referred to as TPU 4, showed the highest thermal decomposition temperature, the largest molecular weight, and most compact matrix structure due to the highest ratio of the hard segment in the molecular structure. It also presented the highest tensile strength, the largest elongation, and the best viscoelastic properties among the different bio TPUs synthesized herein.

• Textile Coloration and Finishing
• /
• v.34 no.4
• /
• pp.261-271
• /
• 2022

Waterborne polyurethane(WPU) is greatly affected by its properties depending on the average particle size. In this study, by analyzing the characteristics of WPUs with different average particle sizes according to the DMPA content and we confirmed that the WPU-Ms have different properties from the physical properties of WPU by mixing two types of WPU with different particle sizes in the same volume. At this time, we mixed WPU at an ideal ratio of 7:3 through literature research. In the thermal characteristic analysis, it was confirmed that the thermal decomposition temperature decreased and Tg increased as the content of DMPA, which is the hard segment, increased. In addition, the average particle size of WPU decreased as DMPA increased, and physical properties and adhesive strength were improved due to increased interaction. When mixed with each other in a weight ratio of 7:3, it was observed that adhesion and mechanical properties were improved compared to only WPU.

• The korean journal of orthodontics
• /
• v.33 no.6 s.101
• /
• pp.475-483
• /
• 2003

The purpose of this study is to evaluate hard and soft tissue changes following the subapical osteotomy in bimaxillary dentoalveolar protrusion patients requiring maximal retraction adult female patients was selected. Surgical procedures were performed by the same surgeon, anterior subapical osteotomy techniques were employed on the maxilla and cephalometric radiograms were traced and superimposed using the best-fit method and two reference The results were as follows 1. The bodily movement of the maxillary anterior segment was achieved in a posterior moved posteriorly with a slight correction of the lower incisors. 2. The horizontal soft tissue measurements changed significantly after treatment, but Nt and Sn vertical soft tissue measurements indicated that Ls moved inferiorly and Li superiorly. 3. The correlation between hard and soft tissue changes indicated that ${\Delta}HId/{\Delta}HLi,\;{\Delta}HId/{\Delta}LL-Eline,\;{\Delta}Hpt.B/{\Delta}HILS,\;and\;{\Delta}UI-FH/{\Delta}NL$ were significant. 4. More lower lip relative to upper lip retraction was demonstrated in relation to Rickett's E-line. The ratio between upper lip displacement was $50\%$, and between the lower incisor and lower lip displacement was $60\%$. We conclude from the results that the anterior subapical osteotomy is an efficient treatment severe dentoalveolar protrusion and desire rapid results.