• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.171-174
• /
• 2004

The stochiometric $AgGaSe_2$ polycrystalline mixture of evaporating materials for the $AgGaSe_2$ single crystal thin film was prepared from horizontal furnace. To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal and semi-insulating GaAs(100) wafer were used as source material and substrate for the Hot Wall Epitaxy (HWE) system, respectively. The source and substrate temperature were fixed at $630^{\circ}C$ and $420^{\circ}C$, respectively. The thickness of grown single crystal thin films is $2.1{\mu}m$. The single crystal thin films were investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of $AgGaSe_2$ single crystal thin films measured from Hall effect by van der Pauw method are $4.89{\times}10^{17}\;cm^{-3},\;129cm^2/V{\cdot}s$ at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $AgGaSe_2$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}S_o$ and the crystal field splitting ${\Delta}C_r$ were 0.1762 eV and 0.2494 eV at 10 K, respectively. From the photoluminescence measurement of $AgGaSe_2$ single crystal thin film, we observed free excition $(E_X)$ observable only in high quality crystal and neutral bound exciton $(D^o,X)$ having very strong peak intensity And, the full width at half maximum and binding energy of neutral donor bound excition were 8 meV and 14.1 meV, respectively. By Haynes rule, an activation energy of impurity was 141 meV.

• Korean Journal of Organic Agriculture
• /
• v.20 no.3
• /
• pp.385-397
• /
• 2012

A pot experiment was carried out to examined the effect of electrolyzed micronutrients (Fe, Mn, Zn, Sr, Se, Sn, Co, Ti, and V) solution treatments with nutrient solution and SCB slurry on the mineral content and growth of tomato in cherry tomato (Lycopersicon esculentum). The treatment of nutrient solution (NS)+micronutrients solution (MS) significantly increased the concentrations of Li, Zn, Sr, Se, Ti as compared with that of NS alone in the cherry tomato fruits, and SCB+MS solution treatment significantly increased Li, Zn, Se, Co, Sr, and Ti contents as compared with SCB treatment. The micronutrient contents of MN+SCB+MS treatment were significantly higher in Li, Zn, Se, Co and in Ti than those of SCB and NS treatment, respectively. The growth and yield of cherry tomato fruits was highest with NS treatment. The yield indices of cherry tomato treated with NS+MS treatment and SCB+NS+MS were 97% and 94% of NS treatment. In conclusion, it seems to be possible to produce micronutrient-fortified cherry tomato by the mixed treatment of electrolyzed micronutrients.

• Journal of Acupuncture Research
• /
• v.19 no.4
• /
• pp.27-41
• /
• 2002

Objective : The purpose of this study is to compare the effect of two other groups(Group A and B) which were treated with two other auricular acupuncture therapy to quit smoking. Methods : Seventy three high-school students were devided in two groups. Group A was treated with auricular acupuncture therapy by burying a needle in one side ear. Group B was not only treated with auricular acupuncture therapy by burying a needle in one side ear, but also treated with venesection on the other side ear. The effects of auricular acupuncture therapy to quit smoking were evaluated at two weeks and six months after the therapy. Results : Group A's score to quit smoking after the auricular acupuncture therapy was higher than Group B's score. Conclusions : Treating with auricular acupuncture therapy by burying a needle in one side ear and venesection on the other side, was effective neither on decreasing the amount of smoking nor on decreasing the desire to smoke compared with the only needle burying treatment.

• Analytical Science and Technology
• /
• v.15 no.5
• /
• pp.439-444
• /
• 2002

DE-O-V ICP-AES has been studied for the analytical characteristics of As, Se, and Ge with PN, USN and HG. Effect of $NaBH_4$ and HCl on the signal intensity of As, Se and Ge with HG and E-O-V ICP-AES were closely investigated. The sensitivities of As, Se and Ge with HG were much greater than those with PN and USN. Accordingly, the detection limits of the elements with HG were lower by a factor of 100 and 10 than PN and USN, respectively.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.21 no.3
• /
• pp.269-278
• /
• 2008

Purpose: The purpose of this study is to report the effect of Traditional Korean Medicine therapy on climacteric symptoms in premature ovarian failure patient. Methods: The patient in this case was 32 years old female. She had a history of the right side ovariectomy and antituberculous chemoteraphy caused by pelvic tuberculosis. And she was diagnosed with premature ovarian failure in October, 2007. She had a climacteric symptoms when she admitted to the OBGY department of Se-Myung University in Je-Cheon. She received Korean Medicine therapies such as herbal medicine, moxibustion, acupuncture. We evaluated patient's health status by Kupperman's index and VAS. Results: After the treatment, the climacteric symptoms in premature ovarian failure patient was improved. Conclusion: This case study shows that Korean Medicine therapies have significant effect on climacteric symptoms in premature ovarian failure.

• Educational Technology International
• /
• v.17 no.2
• /
• pp.203-228
• /
• 2016

This study was designed to determine the factors affecting learner satisfaction and examine the relationships of these factors in mobile learning linked to pre-existing e-learning in universities. In the structural model used, three mobile learning quality factors are the endogenous variables, namely, system quality (SYQ), information quality (INQ) and service quality (SEQ) perceived by students, and learner satisfaction (LS), whereas students' self-efficacy (SE) and experience (EX) in mobile learning are the exogenous variables. The subjects were 900 students who registered for mobile learning courses offered by a private university in Seoul, Korea. The results indicated that SE in mobile learning had positive effects on SYQ, INQ, and SEQ. Furthermore, SE influenced LS when analyzed without quality factors as parameters. Mobile learning EX directly affected INQ, but not SYQ or SEQ. EX likewise had a direct effect on LS when analyzed without quality factors as parameters. Meanwhile, both SYQ and INQ showed a positive effect on LS, but not SEQ. SE and EX affected LS indirectly when SYQ and INQ were used as parameters. This study addresses the importance of increasing SE, EX, SYQ, and INQ to increase LS in mobile learning in universities

• Journal of Sensor Science and Technology
• /
• v.23 no.1
• /
• pp.51-57
• /
• 2014

The evaporating materials for $MgGa_2Se_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $MgGa_2Se_4$ compounded polycrystal powder was deposited on thoroughly etched semi-insulated GaAs(100) substrate by the hot wall epitaxy (HWE) method system. The source and substrate temperatures of optimized growth conditions, were $610^{\circ}C$ and $400^{\circ}C$, respectively.The source and substrate temperatures were $610^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by double crystal X-ray diffraction (DCXD). The temperature dependence of the energy band gap of the $MgGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=2.34\;eV-(8.81{\times}10^{-4}\;eV/K)T^2/(T+251\;K)$. After the as-grown $MgGa_2Se_4$ single crystal thin films was annealed in Mg-, Se-, and Ga-atmospheres, the origin of point defects of $MgGa_2Se_4$ single crystal thin films has been investigated by the photoluminescence (PL) at 10 K. The native defects of $V_{Mg}$, $V_{Se}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Se-atmosphere converted $MgGa_2Se_4$ single crystal thin films to an optical n-type. Also, we confirmed that Ga in $MgGa_2Se_4$/GaAs did not form the native defects because Ga in $MgGa_2Se_4$ single crystal thin films existed in the form of stable bonds.

• Journal of the Korean Vacuum Society
• /
• v.7 no.1
• /
• pp.11-16
• /
• 1998

In this study, we prepared a Na$_2$Se/NH$_4$OH solution to investigate a passivation effect of Se on GaAs surface. X-ray photoelectron spectroscopy and photoluminescence (PL) were used to analyse the surface chemical bonding states and the optical properties of GaAs after Se-treatment and a successive exposure to air, respcetively. It was observed that all of the observed selenium bound with arsenic to form As-Se bond and showed only one oxidation state as -2. PL intensity of Se-passivated surface was larger than that of HCI-cleaned surface, and this means that the effective reduction of surface state density of GaAs was successfully obtained by this treatment. However the existence of partial oxide on the Se-passivated surface was seemed to be a major cause to the degradation of Se passivation effcet. PL intensity of Se-passivated surface also decreased according to air-exposure and converged to that of HCI-cleaned surface.

• Journal of Sensor Science and Technology
• /
• v.8 no.6
• /
• pp.476-480
• /
• 1999

PbSe thin films were grown using PLD method on the p-Si(100) substrate. To determine what crystalline structure of PbSe thin films have according to the growth temperature, the films were prepared under a substrate temperature changing between a room temperature and $400^{\circ}C$. As a result of analyzing XRD patterns of PbSe thin films prepared at various substrate temperatures and FWHM of PbSe(200) rocking curve, it was found that PbSe thin film obtained at the growth temperature of $200^{\circ}C$ was best crystallized. In addition, the surface morphology of PbSe thin film observed using AFM found itself having the most regularly arranged particles in case of growing the film at $200^{\circ}C$. The measurement of Hall effect indicated that PbSe thin films were n-type semiconductors and that current-voltage characteristic curve exhibit the typical p-n junction phenomenon. In addition, electric conductivity of PbSe thin films was found somewhat higher than that of general semiconductors.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.11
• /
• pp.1803-1806
• /
• 2005

Formation of octahedral shaped PbSe quantum dots at higher synthesis temperature is being reported in this paper. The synthesis includes the reaction between lead oleate and trioctylphosphine selenide under inert gas conditions to produce PbSe. TEM, SEM, XRD and EDS were used to characterize the samples. The SEM exhibited the formation of spherical shaped nanocrystals at temperature below 140 ${^{\circ}C}$ and octahedral shaped nanoparticles at higher temperatures. Moreover, the TEM also showed the well resolved (111) lattice fringes proving that the nanocrystals were crystalline in nature. Synthesis of highly pure PbSe nanocrystals was another interesting aspect of this research.