• Korean Journal of Materials Research
• /
• v.31 no.10
• /
• pp.586-591
• /
• 2021

This paper proposes a mathematical model that can calculate the luminescence characteristics driven by alternating current (AC) power using the current-voltage-luminance (I-V-L) properties of organic light emitting devices (OLED) driven by direct current power. Fluorescent OLEDs are manufactured to verify the model, and I-V-L characteristics driven by DC and AC are measured. The current efficiency of DC driven OLED can be divided into three sections. Region 1 is a section where the recombination efficiency increases as the carrier reaches the emission layer in proportion to the increase of the DC voltage. Region 2 is a section in which the maximum luminous efficiency is stably maintained. Region 3 is a section where the luminous efficiency decreases due to excess carriers. Therefore, the fitting equation is derived by dividing the current density and luminance of the DC driven OLED into three regions, and the current density and luminance of the AC driven OLED are calculated from the fitting equation. As a result, the measured and calculated values of the AC driving I-V-L characteristics show deviations of 4.7% for current density, 2.9 % for luminance, and 1.9 % for luminous efficiency.

• Steel and Composite Structures
• /
• v.23 no.1
• /
• pp.17-29
• /
• 2017

The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.

• Korean Journal of Logic
• /
• v.14 no.2
• /
• pp.39-76
• /
• 2011

We explain some basic elements of Martin-L$\ddot{o}$f's type theory and examine the distinction between propositions and judgments. In section 1, we introduce the problem. In section 2, we explain the concept of proposition in the intuitionistic type theory as a development of the intuitionistic conception of proposition. In section 3, we explain the concept of judgment in the intuitionistic type theory. In section 4, we explain some basic inference rules and examine a particular derivation in the theory. In section 5, we examine one route from the Fregean distinction between propositions and judgments to the distinction between them in the intuitionistic type theory, paying attention to the alleged necessity for introducing different forms of judgments.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1998.04a
• /
• pp.135-140
• /
• 1998

The buckling of the perforated web of a simply supported Η-section beam subjected to uniformly distributed load is examined by means of the finite element method. With buckling analysis results, the effect of this hole on the load carrying capacity of the beam with dimensions L/h = 11 and 13 ( L = span length h = web depth) is investigated. The parameters whose variation have been considered are hole size and location. It can be generally concluded that the buckling of the perforated web of an H-section beam is not affected seriously by the location of the perforation.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.3 no.1
• /
• pp.22-36
• /
• 1993

This study was conducted to evaluate the charcoal tube sampling method for carbon disulfide in the air. Breakthrough was investigated according to flow rate, sampling time and air volume. Also the storage stability by storage method and time was investigated. The results are summarized as follows. 1. The samples stored at room temperature($28.2^{\circ}C$), refrigerator($3.8^{\circ}C$) and freezer($-15.6^{\circ}C$) were analyzed every week to five weeks. At one week storage at room temperature, 3.5% of $CS_2$ in the front section of the charcoal tube migrated into the back section and 57.7% at five weeks. The amount of $CS_2$ in the back section of the charcoal increased continuously by storage time. Migration of $CS_2$ was slow at refrigerator, and stopped occur at freezer. Recovery rate $CS_2$ was 52-82% at room temperature and 92-101% at refrigerator, based on the amount at freezer as a reference value. Thus loss was observed at room temperature. 2. When 6-48 L of fresh air were passed through tubes with spiked amounts of 0.379 and 0.759mg sample, the amounts of $CS_2$ in the back section of charcoal were 5.7-132.4 and 0-92% of the amount in the front section, respectively. The total recovery rates of$CS_2$ from 0.379 and 0.759mg spiked sample were 35.7-101.0% and 9l.3-100.1%, respectively. $CS_2$ loss was observed in 0.379mg spiked sample, but not in 0.759mg spiked sample. In the spiked samples, the amount of $CS_2$ in the back section of charcoal was not affected by flow rate when the air volume was controlled. The amount of $CS_2$ in the back section of charcoal increased over sampling time. And the faster the flow rate, the more the migration amount when the sampling time was the same. 3. A known concentration, 10 ppm of $CS_2$, was produced in a 200 L Tedlar bag. When the air volume was 24, 36, 48 L, breakthrough was 5.8, 16.9, 47.4%, respectively. The sampling flow rate of 0.05, 0.1, 0.2 Lpm did not change the breakthrough rate. Breakthrough increased over sampling time. And the faster the flow rate, the more the breakthrough, when the sampling time was the same.

• Journal of Korea Foundry Society
• /
• v.5 no.4
• /
• pp.283-288
• /
• 1985

The melt of highly purified Zn was poured by top pouring process into the open green sand mold, that was made by using the 3-plane L-sections pattern. After skin was formed, the unsolified melt was poured out by rolling-over. The thicknesses of skin for each different of castings were investigated with one dimension. The results obtained and could be summerzed as follows: 1) While the 3-plant L-sections castings were solidifying in the mold, solidification blocks of different section modulus in the castings were formed, i.e. 1-dimension divergency block, 2-dimension heat divergency block, 3-dimension heat divergency block, 2-dimension heat convergency block, and 3-dimension heat convergency block. 2) When the chill plate was set up to the mold in order to change section modulus artificially, heat divergency blocks and heat convergency blocks according to the shape of chill plate were revealed.

• Journal of the Korean Mathematical Society
• /
• v.43 no.6
• /
• pp.1357-1369
• /
• 2006

It is known that if C is an [24m + 2l, 12m + l, d] selfdual binary linear code with $0{\leq}l<11,\;then\;d{\leq}4m+4$. We present a sufficient condition for the nonexistence of extremal selfdual binary linear codes with d=4m+4,l=1,2,3,5. From the sufficient condition, we calculate m's which correspond to the nonexistence of some extremal self-dual binary linear codes. In particular, we prove that there are infinitely many such m's. We also give similar results for additive self-dual codes over GF(4) of length n=6m+1.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.137-139
• /
• 2003

As a part of numerical and experimental research works for the prediction and improvement of ship's maneuvering performance, a study on the performance analysis of two different rudders has been carried out. While the planform shape and the aspect ratio of the rudders have been fixed, section shape has been changed. Conventional type of HMRI NP section and special type of dolphin-tail section have been employed. Performances of the rudders have been investigated by using CFD and compared with experimental data obtained in a wind tunnel. A commercial CFD program has been used to solve the RANS equations. Two-equation k-ro model has been applied to close the governing equations. Block-structured grids are used in the numerical calculation. Based upon the calculation results, the rudder with dolphin-tail section has shown a possibility of significantly improving rudder performance if utilized as the section of ship rudders.

• Transactions on Electrical and Electronic Materials
• /
• v.18 no.2
• /
• pp.62-65
• /
• 2017

In this paper, three DC Block designs are presented which efficiently meet the need of modern-day compactsize wireless communication systems. As one of the important parts of a complete system design, the proposed microstrip-based DC block with coupled transmission lines efficiently attenuates unwanted frequencies that cause damage to the system. The compact-sized DC block structures are created by incorporating an extended coupled-line section with a radial stub, an enveloped coupled-line section, and using alternate up-down meandering techniques. The structures are analyzed for the L-Band using a high-resistive silicon substrate. At a resonating frequency of 1.575 GHz, the designed DC Block structures have a return loss better than -10 dB, an insertion loss of around -1 dB, and also possess wide pass-band characteristics.

• Natural Product Sciences
• /
• v.5 no.1
• /
• pp.39-47
• /
• 1999

The flowers of Alcea rosea L., Malvaceae, sold in the Indian market under the trade name 'Gulkhairo', are well known for their expectorant, cooling and diuretic properties and used in many indigenous cough mixtures in India. The present paper deals with the detailed pharmacognosy of the floral parts including morphological, anatomical, phytochemical and fluorescence characters. Some of the diagnostic features of the drug are : pedicel characterized by multicellular appendages, stellate hairs, rosette crystals of Ca-oxalate, starch sheath and large sized mucilage canals; sepals having distinctive multicellular appendages arranged in a semilunar fashion present adaxially at their base; monadelphous stamens, pollen grains pentaporate provided with dimorphic spines; placentation axile, ovules campylotropous; dark green fluorescence of the powder with nitrocellulose in amyl acetate and yellow fluorescence of trichomes under Fluorescence microscope.