• Polymer(Korea)
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• v.33 no.4
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• pp.371-376
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• 2009

The 1,3-propane diol has been introduced as a co-monomer with ethylene glycol to polymerize the poly(ethylene/propylene naphthalate) in order to improve the dimensional stability of poly(ethylene naphthalate) for a possible flexible substrate material. Based on $^1H$-NMR results, it was found that poly (ethylene/propylene naphthalate) has been synthesised successfully. Introducing 1,3-propane diol resulted in the amorphous state in polyester as well as lowering of glass transition and thermal degradation temperature. Coexisting relatively longer propylene segment compared with ethylene in synthesized polyester caused less orientation behavior and reducing thermal expansion coefficient. This is a promising result for poly (ethylene/propylene naphthalate) to apply a flexible substrate.

• Electrical & Electronic Materials
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• v.7 no.3
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• pp.243-251
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• 1994

ITO(Indium Tin Oxide) film with thickness of 1500.angs. was prepared by an e-beam evaporator onto a glass and a p-type InP wafer (100) LEC grown Zn-doped p=2.3*10$\^$16/cm$\^$-3/), in which the components of ITO used for evaporation source were hot pressed pellets 1 mole% ln$\_$2/O$\_$3/+9 mole% SnO$\_$2/, and evaporated in O$\_$2/ ambient. The optimum conditions to preparation of ITO thin film were the substrate temperature of 350.deg. C, the injected oxygen pressure of 2*10$\^$-4/ torr, and the evaporation speed of 0.2-0.3.angs./sec, respectively. In these optimum conditions, the resistivity and the carrier concentration were 5.3*10$\^$-3/ .ohm.-cm, 6.5*10$\^$20/cm$\^$-3/, and the transmittance was over 80%. From the results of J-V measurements in ITO/p-InP structure solar cells, the higher pressure of injected oxygen, the more open circuit voltage. The efficiency of ITO/p-InP solar cell without the grid line contact, prepared by the optimum evaporation conditions, was 7.19%. By using the grid line contact, the efficiency, the open circuit voltage, the short circuit current density, the fill factor, the series resistance, and the shunt resistance were 8.5%, 0.47V, 29.48 mAcm$\^$-2/ , 61.35%, 3.ohm., and 26.6k.ohm., respectively.

• Journal of the Korea Institute of Building Construction
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• v.3 no.2
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• pp.119-127
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• 2003

Test specimen test was performed using concrete reinforced with fiber sheet and the test variables were based on the kinds of fiber and the number of reinforcement layers. Using steel-concrete reinforced with fiber sheet, compression tests were performed and the test variables were the kinds of fiber, number reinforcement layers and reinforcement layer order. The following results were obtained: 1) It was demonstrated that compressive strength of the test specimen reinforced during test specimen test and member test increased as the number of reinforcement layers increased. 2) It was shown that non-reinforced test, specimen were destroyed during the member tests, but the specimen reinforced with CFS destroyed and the GFS-reinforced specimen and composite reinforced specimen showed ductile destruction. 3) As a result of tests on kinds of reinforcement fiber, it was demonstrated that CFS-reinforced test specimen had higher compressive strength in a 공시체 test. In the member test, 2ply-and 3ply-GFS reinforced specimens except lplied one had higher compressive strength. It was because partial destruction occurred due to the rate of height/section. 4) For layer strength order, compared with test specimen reinforced only with a single reinforced material, test specimen reinforced with CFS and GFS, and test specimen reinforced with CFS first showed better results in compressive strength and ductility judgement.

• Analytical Science and Technology
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• v.16 no.3
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• pp.240-248
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• 2003

Sulfur compounds which are well-known odor-active compounds in industrial area have very low detection threshold values. Trace amounts of volatile sulfur compounds in enviroment air around several odor sources were concentrated in liquid argon bath and determined by gas chromatograph with flame photometric detector (FPD) which exhibits very good selectivity and sensitivity. 25% ${\beta}$,${\beta}$-Oxydipropionitrile on 60/80 Chromosorb W was used as adsorbent for the preconcentration of sulfur compounds in air sample and also as packing material for a packed glass column. Concentration volume of air sample was different from place to place in the range of 0.1~3.0L. Atmospheric concentrations of sulfur compounds in air of residential districts and boundaries of business establishments, and also those in the exhausted gases of emission points such as a sewage disposal plant in industrial area were measured.

• Journal of Korea Foundry Society
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• v.25 no.6
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• pp.259-264
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• 2005

The copper clad steel wire is used extensively as lead wires of electronic components such as capacitors, diodes and glass sealing lamp because the wire combines the strength and low thermal expansion characteristic of Fe-Ni steel with the conductivity and corrosion resistance of copper. In order to fabricate the copper clad steel wire, several processes including electro-plating, tubecladding extrusion process and dip forming process have been introduced and applied. The electroplating process for the production of copper clad steel wire shows poor productivity and induces environmental load generation such as electroplating solution. The dip forming process is suitable to mass production of copper clad steel such as trolley wire. and need expensive manufacturing facilities. The present paper describes the improvement of the conventional continuous casting process to fabricate copper clad steel wire, which its core metal is low thermal expansion Fe-Ni alloy and its sheath material is copper. In particular, the formation of intermetallic compound at interface between core and sheath was investigated in order to introduce optimum continuous casting process parameter for fabrication of copper clad steel wire with higher electrical conductivity. The mechanical strength of copper clad steel wire was also investigated through wiredrawing process with of 95% in total reduction ratio.

• Korean Institute of Interior Design Journal
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• v.21 no.5
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• pp.254-263
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• 2012

This study found out the change of spacial form of detached house in Korea on a 10-year basis from 1980s though analysis on the architecture of each period. For the subject houses of this study, the detached houses introduced repeatedly as excellent cases in technical journals for architecture were collected among those completed by architects who designed numerous houses and a survey was conducted on 18 detached houses of 18 architects among the in urban style houses in Seoul and suburban style houses in the suburbs of Seoul. Through this study, it could be found that, as the morphological application of traditional architecture was settled with spatial concept, the external spatial form of the detached houses in Korea after 1980s was changed to westernized form but the internal spacial form had been continuously changing suitable to our emotion by reflecting the living habit and taste with the traditional attitude to perceive and accept the nature. As for the change in the forms of interior space, vertical space with more than two floors became common. Front porch and stair hall, which were located at the center of a house and became an important spacial element that overlapped family's moving line, changed to open and bright space that used transparent glass and increased the space to contact the open air, reflecting our living habit and taste that preferred the feeling of internal openness. A Private space, main room, was more segmented and luxurious, and a public space, living room, secured the independency by getting close to symbolic yard. As for the change in the form of exterior space, the form of façade window has been changing in its location and size and brought free images due to the advancement of technology and material. The shape of roofs was borrowed from western style and a lot of geometrical forms that break away from the concept of angle rater and eaves are appearing.

• Journal of the Korean Institute of Gas
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• v.13 no.6
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• pp.29-33
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• 2009

In this study, the strength safety of a composite fuel tank which is fabricated by an aluminum liner of Al6061-T6 materials and composite layers of carbon/epoxy-glass/epoxy composites has been analyzed by using a finite element analysis technique. In order to enhance the durability of the composite fuel tank, an autofrettage process was used and compressed natural gas was supplied to the prestressed fuel tank. The FEM computed results on the stress safety of autofrettaged gas tanks were compared with a criterion of design safety of US DOT-CFFC and Korean Standard. The FEM computed results indicated that the stress safety of autofrettaged fuels tanks shows instability at the dome zone and uniform stability at the parallel body, which provide an evaluation data for a strength safety of autofrettaged composite fuel tanks. The computed results show that the stress safety of 9.2 liter composite fuel tanks satisfied the safety criteria of four evaluation items, which are provided by US DOT-CFFC and KS and indicated a safe design.

• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.39-42
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• 2012

To study the physical and chemical properties, solid solutions of $(Sr_{1-x}Ba_x)NdFe{^{3+}}_{1-\tau}Fe{^{4+}}_{\tau}O_{4-y}$ system with x=0.0(SBN-0), 0.1(SBN-1), 0.2(SBN-2) and 0.3(SBN-3) were synthesized in air at 1,473 K and annealed in air at 1,073 K for 24 h. X-ray powder diffraction assured that the four samples had tetragonal symmetries (I4/mmm). Their lattice volumes increased gradually with x values. Nonstoichiometric chemical formulas were formulated using the data such as $\tau$(amount of $Fe^{4+}$ ion) and y(oxygen deficiency) values using Mohr salt analysis. It was found out that all the four samples had excessive oxygen (4-y>4.0). All the samples started to lose some of their oxygen at around 613K(TG/DTA thermal analysis). They exhibited semiconductivities in the temperature range of around 283-1173K. All the four specimens had sufficient tensile strength to endure the force of 19.6 N (2 kg of weights) and the conductivity values of the ECIAs which were painted on pieces of glass with the area of $150mm^2$ ($10mm{\times}15mm$) and it was in the order of ECIA-0${\rightarrow}$ECIA-1${\rightarrow}$ECIA-2${\rightarrow}$ECIA-3 at a constant temperature.

• Journal of Chest Surgery
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• v.44 no.1
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• pp.51-57
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• 2011

Background: Up to now, lobectomy, bilobectomy and pneumonectomy combined with extensive lymph node dissection have been regarded as the standard procedures for non-small cell lung cancer (NSCLC). In high-risk patients, however, limited resection (LR) has been attempted as a salvage procedure, and, recently, indication for LR has been extended to selected cases with early-stage NSCLC. Material and Methods: Among the 773 patients who underwent surgical procedures for NSCLC in Seoul National University Bundang Hospital from May 2003 to December 2008, 43 patients received LR. Medical records of these patients were retrospectively reviewed. Results: Mean age at operation was $66.0{\pm}12.4$ years, and there were 30 males. Twenty-five patients underwent conservative limited resection (CLR) and 18 underwent intentional limited resection (ILR). Indications for CLR were multiple primary lung cancer in 9 (9/25, 36%) and severe concomitant diseases in 5 (5/25, 20%). Of these, 6 patients underwent segmentectomy and 19 received wedge resection. During the follow-up period of $28.0{\pm}17.8$ months, 15 patient developed recurrent lung cancer. ILR was selectively performed in lesions almost purely composed of ground glass opacity (${\geq}$95%), or in small solid lesions (${\leq}$2 cm). Of these, 11 patients underwent segmentectomy and 7 underwent wedge resection. During the follow-up period of $31.7{\pm}11.6$ months, no patient developed recurrence. Conclusion: Intermediate-term outcome of LR for early-stage lung cancer is comparable to that of standard operation. For the delineation of the indications and appropriate surgical techniques for LR, prospective randomized multi-institutional study may be expedient.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.3
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• pp.273-282
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• 2018

Objectives: Dustiness of nanomaterials is considered as exposure index of essential material. Research on dustiness of nanomaterial is needed to control exposure in workplaces. Method: Dustiness measurement using vortex shaker were installed in the laboratory. Nanomaterials, 1 g, was put in the glass test tube and shaked using vortex shaker. Aerosol dispersed was measured using scanning mobility particle sizer(SMPS) and optical particle counter(OPC). Mass concentration using PVC filter and cassette was measured and TEM grid sampling was conducted. Total particle concentration and size distribution were calculated. Image and chemical composition of particles in the air were observed using transmission electron microscopy and energy dispersive X-ray spectrometer. Eleven different test nanomaterials were used in the study. Results: Rank of mass concentration and particle number concentration were coincided in most cases. Rank of nanomateirals with low concentration were not coincided. Two types of fumed silica had the highest mass concentration and particle number concentration. Indium tin oxide, a mixture of indium oxide and tin oxide, had high mass concentration and particle number concentration. Indium oxide had very low mass concentration and particle number concentration. Agglomeration of nanoparticles in the air were observed in TEM analysis and size distribution. In this study, mass concentration and particle number concentration were coincided and two index can be used together. The range of dustiness in particle number concentration were too wide to measure in one method. Conclusion: Particle number concentration ranged from low concentration to high concentration depend on type of nanomaterial, and varied by preparation and amount of nanomaterial used. Further study is needed to measure dustiness of all nanomaterial as one reference method.