• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.183-184
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• 2023

Considering the actual marine environment construction, this paper monitors the mechanical properties (Flexural, Compressive strength) by exposing alumina cement to seawater. As a result of the experiment, it was confirmed that the strength decreases by about -25% when curing in seawater, but the target strength of the product is met, so it is believed that exposure to the actual marine environment will not be significantly affected.

• Structural Engineering and Mechanics
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• v.89 no.6
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• pp.549-556
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• 2024

A serial pendulum dynamic vibration absorber (DVA) was designed to suppress the vibration of two degrees of freedom (Two-DOF) structure model. The optimal DVA parameters are selected using a genetic algorithm (GA) by minimizing the fitness function formulated from the system's frequency response function (FRF). Two fitness function criteria, using one and two target frequency ranges, were utilized to calculate the optimal DVA parameters. The optimized serial pendulum DVA parameters were used to reduce structural vibration under free and forced excitation conditions. The simulation study found that the serial pendulum DVA can effectively reduce the vibration response for a small excitation amplitude. However, the DVA performance decreases for a large excitation amplitude due to the nonlinearity of pendulum motion, and the percentage of vibration response attenuation is smaller than that obtained using a small excitation amplitude.

• Journal of Sensor Science and Technology
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• v.33 no.3
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• pp.147-151
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• 2024

The importance of Wireless Sensor Networks is becoming more evident owing to their practical applications in various areas. However, the energy problem remains a critical barrier to the progress of WSNs. By reducing the energy consumed by the sensor nodes that constitute WSNs, the performance and lifespan of WSNs will be enhanced. In this study, we introduce an energy-efficient ternary modulator that employs multi-threshold CMOS for logic conversion. We optimized the design with a low-power ternary gate structure based on a pass transistor using the MTCMOS process. Our design uses 71.69% fewer transistors compared to the previous design. To demonstrate the improvements in our design, we conducted the HSPICE simulation using a CMOS 180 nm process with a 1.8V supply voltage. The simulation results show that the proposed ternary modulator is more energy-efficient than the previous modulator. Power-delay product, a benchmark for energy efficiency, is reduced by 97.19%. Furthermore, corner simulations demonstrate that our modulator is stable against PVT variations.

• The Korean Journal of Financial Management
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• v.24 no.1
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• pp.109-147
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• 2007

According to the perspective of capital structure theory, we analyzed the dynamism of the capital structure determinants by using panel data of 244 KOSDAQ firms based on two-step GMM system methodology suggested by Blundell Bond(1998). This dynamic methodology had not been used to analyse capital structure determinants in Korea. In the dynamic model of capital structure, profit had negative effect on the book leverage and market leverage, which meant supporting pecking order theory. Growth opportunity (MBR) affected negatively to the market leverage. For the determinants of leverage, earnings volatility had significantly positive effect on KOSDAQ 50 firms. KOSDAQ and KOSDAQ 50 firms had the target leverage. The adjustment speed in KOSDAQ firms was 0.4958 on the book leverage, it was faster than in KOSDAQ 50 firm's 0.2863 on the book leverage and the adjustment speeds for the market leverage were 0.7651 for KOSDAQ firms and 0.5643 for KOSDAQ 50 firms. There was difference in adjustment cost between KOSDAQ firms and KOSDAQ 50 firms.

• Current Photovoltaic Research
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• v.8 no.1
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• pp.33-38
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• 2020

Single-phased SnS thin films have been prepared by RF magnetron sputtering at various deposition pressures. The effect of deposition pressure on the structural and optical properties of polycrystalline SnS thin films was studied using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometer. The XRD analysis revealed the orthorhombic structure of the SnS thin films oriented along the (111) plane direction. As the deposition pressure was increased from 5 mTorr to 15 mTorr, the intensity of the peak on the (111) plane increased, and the intensity decreased under the condition of 20 mTorr. The binding energy difference at the Sn 3d_5/2 and S 2p_3/2 core levels was about 324.5 eV, indicating that the SnS thin film was prepared as a pure Sn-S phase. The optical properties of the SnS thin films indicate the presence of direct allowed transitions with corresponding energy band gap in the rang 1.47-1.57 eV.

• Korean Journal of Crystallography
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• v.16 no.1
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• pp.21-29
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• 2005

The crystal structure of an enantiomeric compound di-(2-picolyl)sulfur dichloro zinc(II), $C_{12}H_{12}N_2SCl_2Zn$, could be elucidated with two space groups $P4_12_12\;and\;P4_32_12$. However, its absolute configuration with the space group $P4_12_12$ was confirmed by means of the effect of anomalous dispersion.

• Journal of Korean Public Health Nursing
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• v.12 no.2
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• pp.149-171
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• 1998

This study attempted to find out a way which is to establish a desirable value and social culture related to sexuality. This study examined student's value and preference about sex and at the same time resolving method to correct ill-rooted value of male preference in our social culture. This study subjects consisted of 409 male and female students of a college located in Incheon area. The study data collected from June 5th to June 11th. 1998. Survey technique was chosen to collect data and analized by SPSS/PC+, SAS program using statistical methods of frequency. percent. $X^ 2-test$ and t-test. The study results are as follows ; 1) Sex satisfaction score of male students was higher than female students and the difference was significant statistically (p<0.0001). 2) There was a difference between male and female student's thought that our socity's structure has a sex discrimination. But female students felt strongly unequality of sex in our socity. 3) $65.4\%$ of total students have a general knowledge about sex and female student's score was higher than male students. The high percent of students get into know sex through mass media $(32.6\%)$ and peer groups $(31.9\%)$. 4) Student's attitude to sex was different from male and female students. Male students have more liberal attitude about sex than female students. 5) $97.1\%$ of the total students believe that our socity has son preference. 6) $86.5\%$ of the total students thought that sex ratio disproportion resulted from male preference is worriable problems in our socity. But there was no significant difference between both sexes.

• The Journal of Engineering Geology
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• v.12 no.3
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• pp.305-317
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• 2002

Geological, structural, and fracture density maps were drawn up to clarify the groundwater flow system around the Geumjeong Mountain, Busan. The results show that the topographical basin formed in the Sanseong Town is considered as a major recharge area of groundwater around the Geumjeong Mt. Because NS-trending fault and ENE-trending fault are intersecting and NS-trending and EW-trending fracture sets are highly developed in the basin, it is believed that the geological structure was developed in the basin which facilitates ground recharge. Based on the density distributions and characteristics of fractures, it is possible that the recharged groundwater in the basin would circulate to the depth of about 3~4 km and finally would reach the Dongnae Hot-spring region.

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.341-347
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• 2013

There are insufficient cadaver-used practice programs for paramedic student education. To provide the basic data for the effective cadaver practice program, the study interviewed 255 students in department of EMT, who attended cadaver practicum. The results indicated that the average satisfaction level in education was 4.5 out of 5 and in relation to allotted time was 3.61 out of 5. The average understanding level of was 4.5 out of 5. In conclusion, senior students who have already taken clinical education & clinical procedure are recommended to focus on clinical anatomy practice and lower grade students are recommended to focus on understanding human body structure in cadaver-used practice program.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.432.2-432.2
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• 2014

Recently, colloidal core/shell type quantum dots lighting-emitting diodes (QDLEDs) have been extensively studied and developed for the future of optoelectronic applications. In the work, we fabricate an inverted CdSe/ZnS quantum dot (QD) based light-emitting diodes (QDLED)[1]. In order to reduce work function of indium tin oxide (ITO) electrode for inverted structure, a very thin (<10 nm) polyethylenimine ethoxylated (PEIE) is used as surface modifier[2] instead of conventional metal oxide electron injection layer. The PEIE layer substantially reduces the work function of ITO electrodes which is estimated to be 3.08 eV by ultraviolet photoemission spectroscopy (UPS). From transmission electron microscopy (TEM) study, CdSe/ZnS QDs are uniformly distributed and formed by a monolayer on PEIE layer. In this inverted QD LED, two kinds of hybrid organic materials, [poly (9,9-di-n-octyl-fluorene-alt-benzothiadiazolo)(F8BT) + poly(N,N'-bis (4-butylphenyl)-N,N'-bis(phenyl)benzidine (poly-TPD)] and [4,4'-N,N'-dicarbazole-biphenyl (CBP) + poly-TPD], were adopted as hole transport layer having high highest occupied molecular orbital (HOMO) level for improving hole transport ability. At a low-operating voltage of 8 V, the device emits orange and red spectral radiation with high brightness up to 2450 and 1420 cd/m2, and luminance efficacy of 1.4 cd/A and 0.89 cd/A, respectively, at 7 V applied bias. Also, the carrier transport mechanisms for the QD LEDs are described by using several models to fit the experimental I-V data.