• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.23 no.1
• /
• pp.16-22
• /
• 2011

The objective of the present study is to investigate the dividing two-phase flow in a horizontal micro T-junction with the same rectangular cross section, $800\;{\mu}m{\times}800\;{\mu}m$, experimentally. Air and water were used as the test fluids. The superficial velocity ranges of air and water were 15~20 m/s and 0.11~0.2 m/s, respectively. Dividing flow characteristics at the micro T-junction are different from those at the larger T-junctions (5~10 mm in hydraulic diameter). Compared with the results of previous works related with the T-junction with mini cross sections (about 5 mm), for lower range of gas separation, the fraction of the liquid separated through the branch decreases for the fixed fraction of the gas separation. But for higher range of gas separation, higher liquid separation could be found.

• Journal of Korean Neurosurgical Society
• /
• v.29 no.6
• /
• pp.805-809
• /
• 2000

Hemangioblastoma of the central nervous system rarely occurs in cervicomedullary junction. The unique pathologic features of the tumor involving midline structures are grossly solid in consistency and accompanying extensive spinal cord enlargement. A 63-year-old women presented with progressive right motor weakness and tingling sensation. The MR image showed a well enhancing mass having a cyst and diffuse cord enlargement in the cervicomedullary junction. A total surgical resection was performed and hemangioblastoma was histologicaly verified. Postoperative MR image showed the disappearance of cord enlargement. The right motor weakness was also improved. The authors report a rare case of hemangioblastoma in cervicomedullary junction and the pathophysiology of the spinal cord enlargement are discussed.

• Journal of Korean Neurosurgical Society
• /
• v.40 no.2
• /
• pp.117-121
• /
• 2006

The surgical removal of solid deep-seated hemangioblastomas remains challenging, because treatment of these lesions is often complicated by severe bleeding associated with the rich vascularity of this tumor, and by severe neural tissue injury associated with the difficulty of en bloc resection, especially when the tumor is located at the cervicomedullary junction. Therefore, preoperative embolization of deep-seated solid hemangioblastomas may play an important role in successful surgical removal by reducing major bleeding and neural tissue damage. A 24-year-old woman, 28-weeks pregnant, was admitted to our hospital for the evaluation of quadriparesis, and brain magnetic resonance imaging[MRI] revealed intra-axial mass lesion in the cervicomedullary junction. After delivery, her neurologic symptoms became aggravated, and we decided to operate. Preoperative angiography revealed a hypervascular tumor in the posterior fossa, and embolization of the main feeding artery using gelfoam and microcoil, resulted in marked reduction of tumor vascularity. She underwent a midline suboccipital craniotomy involving the removal of the arch of C-1. The tumor was totally removed through a midline myelotomy, and at her 6-month follow-up she walked independently. We report on the combined use of the preoperative embolization of feeding vessels and subsequent operative resection in a patient with a solid hemangioblastoma at the cervicomedullary junction immediately after delivery.

• 한국초전도학회:학술대회논문집
• /
• v.9
• /
• pp.223-228
• /
• 1999

We have investigated the microwave properties of a high-T$_c$. superconducting Josephson junction by Shapiro step measurements. A Josephson junction was fabricated on the bicrystal MgO substrate using pulsed laser deposition method. We have measured Shapiro steps in the I-V characteristics under the irradiation of 1.36 cm wavelength up to 45 K and found inclined current steps above 50 K. In order to understand these results, we introduced an additional resistance connected in series to RSJ model. Using this modified RSJ model, we could explain the inclined current steps as a result of superposition of the junction and an additional resistance above certain temperatures. Also, we presented the received power of the Josephson junction above 50 K.

• 한국정보통신설비학회:학술대회논문집
• /
• 2009.08a
• /
• pp.36-39
• /
• 2009

We developed an optimal design interface based on VBA(Visual Basic Application) that takes advantage of API(Application Program Interface) function of commonly used EM analysis software. The developed interface is adopted for an optimal design of a septum in a waveguide tee junction using PSO(Particle Swarm Optimization) algorithm. The objective function of the optimal design is defined by $S_{11}$-parameter of the waveguide tee junction Design variables are established as position of the septum, that are changed to satisfy the design goal Using the developed design interface and PSO algorithm, the objective function converged to the smallest value, showing the validity of the proposed method. The design interface was developed using Microsoft Excel software, enabling easy control of design parameters for user. Also, various analysis parameters can be set in the Excel interface, including waveguide input mode and frequency. After completion of the design, field solutions at user-specified positrons can be extracted to the output files in complex number form.

• BMB Reports
• /
• v.29 no.1
• /
• pp.1-10
• /
• 1996

The binding interaction of ethidium to a series of synthetic deoxyoligonucleotides containing a B-Z junction between left-handed Z-DNA and right-handed B-DNA, was studied. The series of deoxyoligonucleotides was designed so as to vary a dinucleotide step immediately adjacent to a B-Z junction region. Ethidium binds to the right-handed DNA forms and hybrid B-Z forms which contain a B-Z junction, in a highly cooperative manner. In a series of deoxyoligonucleotides, the binding affinity of ethidium with DNA forms which were initially hybrid B-Z forms shows over an order of magnitude higher than that with any other DNA forms, which were entirely in B-form DNA The cooperativity of binding isotherms were described by an allosteric binding model and by a neighbor exclusion model. The binding data were statistically compared for two models. The conformation of allosterically converted DNA forms under binding with ethidium is found to be different from that of the initial B-form DNA as examined by CD spectra. The ratio of the binding constant was interestingly correlated to the free energy of base unstacking and the conformational conversion of the dinucleotide. The more the base stacking of the dinucleotide is unstable, or the harder the conversion of B to A conformation, the higher the ratio of the binding constant of ethidium with the allosterically converted DNA forms and with the initial B-Z hybrid forms. DNA sequence around a B-Z junction region affects the binding affinity of ethidium. The results in this study demonstrate that ethidium could preferentially interact with unusual DNA structures.

• Progress in Superconductivity
• /
• v.11 no.2
• /
• pp.96-99
• /
• 2010

We measured electrical shot noise in a metal-insulator-metal tunnel junction, which was made by using electron-beam lithography and double-angle evaporation technique. Since the dependence of the shot noise on bias voltage and temperature is theoretically well known, we can determine the temperature of the junction by measuring the noise as the voltage across the junction is changed. A cryogenic low noise amplifier was used to amplify the noise signal in the frequency range of 600-800 MHz, which enabled fast measurement of noise signal and thus temperature. With further study, this method could be useful for primary thermometry in cryogenic temperatures.

• Journal of the Korean Vacuum Society
• /
• v.19 no.5
• /
• pp.391-396
• /
• 2010

The pn junction for solar cell was prepared on p-type Si wafer by the furnace using the $POCl_3$ and oxygen mixed precursor to research the characteristic of interface at pn junction. The sheet resistance was decreased in accordance with the increasing the diffusion process time for n-type doping on p-type Si wafer. The electron affinity at the interface in the pn junction was decreased with increasing the amount of n-type doping and the sheet resistance also decreased. Consequently, the drift current due to the generation of EHP increased because of low potential barrier. The efficiency and fill factor were increased at the solar cell with increasing the diffusion process time.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.11
• /
• pp.3128-3132
• /
• 2010

A disposable solid-state pH sensor was realized by utilizing two nanoporous Pt (npPt) electrodes and a copolyelectrolytic junction. One nanoporous Pt electrode was to measure the pH as an indicating electrode (pH-IE) and the other assembled with copolyelectrolytic junction was to maintain constant open circuit potential ($E_{oc}$) as a solid-state reference electrode (SSRE). The copolyelectrolytic junction was composed of cationic and anionic polymers immobilized by photo-polymerization of N,N'-methylenebisacrylamide, making buffered electrolytic environment on the SSRE. It was expected to make. The nanoporous Pt surrounded by a constant pH excellently worked as a solid state reference electrode so as to stabilize the system within 30 s and retain the electrochemical environment regardless of unknown sample solutions. Combination between the SSRE and the pH-IE commonly based on nanoporous Pt yielded a complete solid-state pH sensor that requires no internal filling solution. The solid state pH sensing chip is simple and easy to fabricate so that it could be practically used for disposable purposes. Moreover, the solid-state pH sensor successfully functions in calibration-free mode in a variety of buffers and surfactant samples.

• Ceramist
• /
• v.22 no.2
• /
• pp.146-169
• /
• 2019

To overcome the theoretical efficiency of single-junction solar cells (> 30 %), tandem solar cells (or multi-junction solar cells) is considered as a strong nominee because of their excellent light utilization. Organic-inorganic halide perovskite has been regarded as a promising candidate material for next-generation tandem solar cell due to not only their excellent optoelectronic properties but also their bandgap-tune-ability and low-temperature process-possibility. As a result, they have been adopted either as a wide-bandgap top cell combined with narrow-bandgap silicon or CuIn_xGa_(1-x)Se₂ bottom cells or for all-perovskite tandem solar cells using narrow- and wide-bandgap perovskites. To successfully transition perovskite materials from for single junction to tandem, substantial efforts need to focus on fabricating the high quality wide- and narrow-bandgap perovskite materials and semi-transparent electrode/recombination layer. In this paper, we present an overview of the current research and our outlook regarding perovskite-based tandem solar technology. Several key challenges discussed are: 1) a wide-bandgap perovskite for top-cell in multi-junction tandem solar cells; 2) a narrow-bandgap perovskite for bottom-cell in all-perovskite tandem solar cells, and 3) suitable semi-transparent conducting layer for efficient electrode or recombination layer in tandem solar cells.