• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.2
• /
• pp.102-107
• /
• 2003

This study puts focus on the optimization of growth temperature of CIGS absorber layer which affects severely the performance of solar cells. The CIGS absorber layers were prepared by three-stage co-evaporation of metal elements in the order of In-Ga-Se. The effect of the growth temperature of 1st stage was found not to be so important, and 350$^{\circ}C$ to be the lowest optimum temperature. In the case of growth temperature at 2nd/3rd stage, the optimum temperature was revealed to be 550$^{\circ}C$. The XRD results of CIGS films showed a strong (112) preferred orientation and the Raman spectra of CIGS films showed only the Al mode peak at 173cm$\^$-1/. Scanning electron microscopy results revealed very small grains at 2nd/3rd stage growth temperature of 480$^{\circ}C$. At higher temperatures, the grain size increased together with a reduction in the number of the voids. The optimization of experimental parameters above mentioned, through the repeated fabrication and characterization of unit layers and devices, led to the highest conversion efficiency of 15.4% from CIGS-based thin film solar cell with a structure of Al/ZnO/CdS/CIGS/Mo/glass.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.12 no.1
• /
• pp.62-68
• /
• 1999

Ferroelectric $Sr_{0.7}/B_{2.3}(Ta_{1-x}Nb_x)_2O_9$(x=0, 0.1, 0.2, 0.3) thin films were deposited on $Pt/SiO_2/Si$ substrate by MOD(Metalorganic Decomposition) process. Metal carboxylate and metal alkoxide were used as precursors, and 2-methoxyethanol, xylene as solvents. After spin coating, thin films were pre-annealed at $400^{\circ}C$, followed by RTA(Rapid Thermal Annealing) and final annealing at $800^{\circ}C$ in oxygen atmosphere. These procedures were repeated three times to obtain thin films with the thickness of $2000{\AA}$. To enhance the nucleation and growth of layered-perovskite phase, thin films were rapid-thermally annealed above $720^{\circ}C$ in oxygen atmosphere. As RTA temperature increased, fluorite phase was transformed to layered-perovskite phase. And the change of Nb contents affected dielectric / electrical properties and microstructure. The ferroelectric characteristics of $Sr_{0.7}/B_{2.3}(Ta_{1-x}Nb_x)_2O_9$ thin film were Pr=8.67 $\mu{C}/cm^2$, Ec=62.4kV/cm and $I_{L}=1.4\times10^{-7}A/cm^2$ at the applied voltage of 5V, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.4
• /
• pp.846-853
• /
• 2004

This paper introduces implementation of a traffic distributed processing system on the Web Sever Networking. The study used two software packages （Packet Capture and Round-Robin Test Package） to check packet quantity from Virtual Network Structure (data generator, virtual server, Serve. 1, 2, 3), and could find out traffic distribution toward Server 1, 2, and 3. The functions of implemented Round-Robin Load Balancing Monitoring System include Round-Robin testing, system monitoring, and graphical indication of data transmission/packet quantity (figures ＆ diagram). As the result of the study shows, Round-Robin Algorithm ensured definite traffic distribution, unless incoming data loads differ much. Although error levels were high in some cases, they were eventually alleviated by repeated tests for a long period of time.

• Journal of Pharmacopuncture
• /
• v.4 no.2
• /
• pp.17-25
• /
• 2001

By process of treatment for a case which diagnosed as HNP of left posterolateral aspect of L4/5 disc and treated from the 10th, May 2001 to the 23rd, Jun 2001, the results are as follows. Method & Results : This patient was medicated Hwallaktang-gami, taken acupuncture, phototherapy, TENS, electric acupuncture, exercises, Mori Cortex-bee venom acupuncture. As a result, the patient's clinical symptom were improved but a computed tomagraphy confirmed L4/5 and L5/S1 HNP was not changed as seen on repeated CT scanning. Conclusion : These results suggest that among conservative therapies the oriental medical treatments including Mori Cortex-bee venom acupuncture improve clinical symptom effectively. But in this case, the structure of herniated disc was not changed.

• Journal of Sensor Science and Technology
• /
• v.7 no.4
• /
• pp.234-242
• /
• 1998

Changes in transmission and thermoluminescent characteristics were used in order to find out the optimum growth condition of CsI single crystal scintillators which were made relatively defect-free using Czochralski method. Impurity distribution in the crystals and the intensity and number of thermoluminescent glow peaks decreased as the process of crystallization was repeated. The direction of crystal growth turned out to be (110), the crystal structure of grown CsI was bee, and its lattice constant was found to be $4.568{\AA}$. The activation energy (trap depths) of CsI:3rd was 0.45 eV and its frequency factor was $5.18{\times}10^5\;sec^{-1}$.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.26 no.3_4
• /
• pp.402-411
• /
• 2002

The objective of this study was to investigate sensibility images of Korean traditional motifs cognized by college students in U.S.A. The subjects consisted of 217 male and 351 female undergraduate students. The experimental materials used in this study were 48 stimuli and questionnaires, composed of 7-point semantic differential scales of 15 bipolar adjectives. Twelve motifs selected from 3 groups of Korean motifs were used as motif stimuli. Twelve repeated patterns were constructed from them to be applied on a CAD-simulated dress. The data were analyzed by factor analysis, ANOVA, Duncan's multiple range test. The major finding were as follows: 1. Four dimensions were emerged accounting for the dimensional structure of the images of Korean traditional motifs. These dimensions were ‘quality’, ‘simplicity’, ‘cheerfulnees’, and ‘modernity’. Among them, ‘quality’and ‘simplicity’were the major dimensions. 2. Category, interpretation type, composition type, and application object had significant effects on the images of above-mentioned dimensions. The interpretation type had a significant effect on ‘quality’image, the composition type on ‘cheerful’image, and the application object on ‘modernity’image.

• The Korean Journal of Pesticide Science
• /
• v.6 no.3
• /
• pp.202-208
• /
• 2002

A phytotoxin was purified by repeated chromatography from liquid cultures of Fusarium oxysporum BG isolated from barnyardgrass. Its chemical structure was determined to be dehydrofusaric acid by mass and NMR spectral analyses. The substance showed a potent phytotoxic activity against growth of duckweed with a $EC_{50}$ value of $1.5{\mu}g/ml$. It also inhibited the root growth of barnyard millet, cress, barnyard grass, and rice cultivar 'Dongjin'. However, it had no inhibitory activity against seed germination of barnyard millet and cress, and the shoot growth of the four plant species.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.1
• /
• pp.426-438
• /
• 2020

This study aimed to identify the components of the nurses' exposure experiences and clarify the semantic structure of nurses by analyzing the participants' experiences of exposure to radiation. The participants in this study were nine nurses who worked for at least six months in the operating room of a City General Hospital. The data were collected using in-depth interviews and analyzed using the phenomenological method by Giorgi's (2004). As a result, six components were derived: "worrying about the disease by repeated radiation exposures", "exhausting physically and mentally," "trying to protect themselves against radiation exposure", "feeling of internal confusion and conflict", "demanding improvement of work environment", and "accepting and adapting to reality". In conclusion, nurses participating in radiation exposure surgery are concerned about the possibility of disease, experience physical and mental fatigue, and then consider changing their occupation. On the other hand, they try to accept and adapt to reality by considering the possibility of a job change or trying to protect themselves from the harsh environment. To develop a radiologically safe environment, systematic and effective resolutions must be secured at the organizational level.

• Resources Recycling
• /
• v.9 no.4
• /
• pp.37-43
• /
• 2000

Leaching of $LiCoO_2$ as a cathodic active materials for recovering Li and Co from spent lithium ion battery was investigated in terms of reaction variables. At the optimum condition determined in the previous work, Li and Co in a $H_2SO_4$ and $HNO_3$ solution were dissolved 70~80% and 40%, respectively. Li and Co were leached over 95% with the addition of a reductant such as $Na_2S_2O_3$ or $H_2O_2$. This behavior is probably due to the reduction of $Co^{3+}$ to $Co^{2+}$. Leaching of $LiCoCo_2$ powder obtained by calcination of an electrode materials from spent batteries was also carried out. Leaching efficiency of Li and Co were over 99% at the optimum condition with $H_2O_2$ addition of 1.7 vol.%. It seems to be due to the activation of $LiCoO_2$ by repeated charging and discharging or an imperfect crystal structure by deintercalation of Li.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.2
• /
• pp.17-23
• /
• 2016

It is essential to develop an estimation and cancellation algorithm for feedback signals in designing the interference cancellation systems (ICS) as a solution to extending the coverage of the TDD LTE networks. Unlike the radio access of FDD LTE networks, TDD networks utilize the same frequency band in downlink and uplink for radio access. For this reason, downlink and uplink are repeated in time and thus the estimation of the feedback signals in uplink and downlink, respectively, is periodically paused to cause performance degradation. In this study, the reciprocity of downlink and uplink is examined through experiments and exploiting the same frequency band in uplink and downlink, an efficient channel estimation and elimination algorithm is proposed since the algorithm utilizes the same structure for both downlink and uplink.