• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.31.4-32
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• 2016

Observing the solar atmosphere with ground-based telescopes in the near-infrared has a number of advantages when compared to classical measurements in visible wavelengths. One of them comes from the magnetic sensitivity of spectral lines, which varies as ${\lambda}_g$, where g is the effective $Land{\acute{e}}$ factor of the transition. This wavelength dependence makes the near-infrared range adequate to study subtle spatial or temporal variations of the magnetic field. Spectral lines, such as the photospheric Fe I $1.5648{\mu}m$ spectral line, with a $Land{\acute{e}}$ factor g=3, have often been used in the past for this type of studies. To study the chromosphere, the Ca II IR triplet and the He I $1.0830{\mu}m$ triplet are the most often observed lines. The latter has the additional advantage that the photospheric Si I $1.0827{\mu}m$ is close enough so that photosphere and chromosphere can be simultaneously recorded with a single detector in a spectrograph. The instrument TIP (Tenerife Infrared Polarimeter) has been continuously operating since 1999 at the 70-cm German VTT of the Observatorio del Teide and has been recently moved to the 1.5-m German GREGOR. During all this time, results have been obtained concerning the nature of the weak photospheric magnetic field of the quiet sun, magneto-acoustic wave propagation, evolution with the cycle of sunspot magnetic fields, photospheric and chromospheric magnetic field in emerging regions, magnetic field in chromospheric structures such as filaments, prominences, flares, and spicules, etc. In this talk, I will review the main results obtained after all these observations and mention the main challenges for the future. With its novel polarization-free design and a complete suite of instruments aimed at simultaneous (imaging and spectroscopic) observations of the solar photosphere and chromosphere, the EST (European Solar Telescope) will represent a major world-wide infrastructure to understand the physical nature of all these phenomena.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.3
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• pp.213-221
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• 2012

The present study numerically investigates the interaction between a free-surface and flow around a circular cylinder over a moving wall. In order to simulate the flow past the circular cylinder over a moving wall near a free-surface, this study has adopted the direct-forcing/fictitious domain (DF/FD) method with the level set method in the Cartesian coordinates. Numerical simulation is performed for a Reynolds numbers of 100 in the range of $0.25{\leq}g/D{\leq}2.00$ and $0.5{\leq}h/D{\leq}2.00$, where g/D and h/D are the gaps between the cylinder and a moving wall and the cylinder and a free-surface normalized by cylinder diameter D, respectively. According to g/D and h/D, the vortex structures have been classified into three patterns of the two-row, one-row, steady elongation. In general, both of g/D and h/D have the large values which mean the cylinder is far away from the wall and the free-surface, two-row vortex structure forms in the wake. When g/D decreases, the two-row vortex structure gradually transfers into the one-row vortex structure. When the g/D reveals the critical value below which the flow becomes steady state, resulting in the steady elongation vortex.

• Economic and Environmental Geology
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• v.37 no.6 s.169
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• pp.657-667
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• 2004

Arsenic was detected in the 29 water samples out of the 46 groundwaters located in the Ulsan metropolitan area and it's concentration ranges from $<0.1\;to\;72{\mu}g/L$. Among them the arsenic concentrations of three samples are over domestic drinking-water requirements $(50{\mu}g/L)$, and those of 10 samples are more than WHO MCLs, $10{\mu}g/L.$. High arsenic groundwater were recognized in the two region; one was near the tectonic line, especially Ulsan iron mine at Dalcheunri and the other was around Hyomundong distributed Jeongia conglomerate. It is estimated that the former is originated from pyrite oxydation type, oxygenated redox, whilst the latter is resulted from oxidation of reducted FeOOH. The species of arsenic in groundwater is in pentavalent arsenic, $H_2AsO_4^-,\;HAsO4_^{-2}$ near tectonic line, and trivalent arsenic, $H_3AsO_3$ around Hyomundong.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.39-47
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• 2009

The effects of thermo-solutal convection on mercurous chloride system of ${Hg_2}{Cl_2}$, and Ne during physical vapor transport are numerically investigated for further understanding and insight into essence of transport phenomena, For $10\;K{\le}{\Delta}T{\le}30\;K$, the growth rate slowly increases and, then is decreased gradually until ${\Delta}T$=50 K, The occurrence of this critical point near at ${\Delta}T$=30 K is likely to be due to the effects of thermo-physical properties stronger than the temperature gradient corresponding to driving force for thermal convection. For the range of $10\;Torr{\le}P_B{\le}300\;Torr$, the rate is second order-exponentially decayed with partial pressures of component B, $P_B$. For the range of $5{\le}M_B{\le}200$, the rate is second order-exponentially decayed with a function of molecular weight of component B, $M_B$. Like the case of a partial pressure of component B, the effects of a molecular weight arc: reflected through the binary diffusivity coefficients, which are intimately related with suppressing the convection flow inside the growth enclosure, i,e., transition from convection to diffusion-dominant flow mode as the molecular weight of B increases. The convective mode is near at a ground level, i,e., on earth (1 $g_0$), and the convection is switched to the diffusion mode for $0.1\;g_0{\le}g{\le}10^{-2}g_0$, whereas the diffusion region ranges from $10^{-2}g_0$ up to $10^{-5}g_0$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.511-516
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• 2004

As a preliminary study on the sediment flux, concentrations of suspended particulate matter and current speeds were measured at three inlets of Gwangyang Bay during one tidal cycle of a spring tide of March 2003. The suspended sediment flux rate $(g/m^{2}/s)$ at the mouth of Seomjin River (St. K1) was observed to be higher throughout surface layer during ebb tide $(14.3\;g/m^{2}/s)$ and throughout near-bottom layer during the flood tide $(23.2\;g/m^{2}/s),$ resulting in a net upstream-ward transport of$0.9{\times}10^{3}kg/m$ during 13 period. At the inlet toward Yeosu Bay (St. K2), a relatively low rate ($(5.0-6.7\;g/m^{2}/s)$ of sediment flux occurred throughout the water column compared to St. K1, with a depth-integrated net transport of $5.6{\times}10^{3}kg/m$ toward the outer reaches of Gwangyang Bay inlet. At St. K3 located at Gwangyang Bay-side of Noryang Strait, the outward flux toward the Jinju Bay was observed to be dominant during the flood tide $(16.2-23.2\;g/m^{2}/s)$, especially through the mid and near bottom layer, compared to the inward flux throughout the whole water column during the ebb tide $(13.1-19.7\;g/m^{2}/s).$ The net transport at St. K3 was calculated to be $4.0{\times}10^{3}kg/m$ toward the outside of Gwangyang Bay. The outward net transport of suspended sediment at all three inlets seems to be consistent with a trend of bottom sediment texture, which suggests a net movement of sediment from a relatively coarse and poorly sorted inner-bay toward a relatively fine and better sorted outer-bay environment.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.27.4-28
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• 2015

The GMT-Consortium Large Earth Finder (G-CLEF) is an optical band echelle spectrograph that has been selected as the first light instrument for the Giant Magellan Telescope (GMT). G-CLEF is a general purpose high dispersion instrument that is fiber-fed and capable of extremely precise radial velocity measurements. G-CLEF has undergone a preliminary design review in April 2015 and is now entering final design phase and construction. G-CLEF has been designed to measure the mass of Earth-analogue exoplanets and to make critical observations in near-field and high-Z cosmology. We describe the G-CLEF instrument and several key science missions that shaped the development of G-CLEF. First light on the GMT is scheduled for late 2020.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.4102-4102
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• 2001

In multivariate analysis, absorbance spectrum is measured over a band of wavelengths. One does not often pay attention to the size of this wavelength band. However, it is desirable that spectrum is measured at only necessary wavelengths as long as the acceptable accuracy of prediction can be met. In this paper, the method of selecting an optimal band of wavelengths based on the loading vector analysis was proposed and applied for determining total protein in human serum using near-infrared transmission spectroscopy and PLSR. Loading vectors in the full spectrum PLSR were used as reference in selecting wavelengths, but only the first loading vector was used since it explains the spectrum best. Absorbance spectra of sera from 97 outpatients were measured at 1530∼1850 nm with an interval of 2 nm. Total protein concentrations of sera were ranged from 5.1 to 7.7 g/㎗. Spectra were measured by Cary 5E spectrophotometer (Varian, Australia). Serum in the 5 mm-pathlength cuvette was put in the sample beam and air in the reference beam. Full spectrum PLSR was applied to determine total protein from sera. Next, the wavelength region of 1672∼1754 nm was selected based on the first loading vector analysis. Standard Error of Cross Validation (SECV) of full spectrum (1530∼l850 nm) PLSR and selected wavelength PLSR (1672∼1754 nm) was respectively 0.28 and 0.27 g/㎗. The prediction accuracy between the two bands was equal. Wavelength selection based on loading vector in PLSR seemed to be simple and robust in comparison to other methods based on correlation plot, regression vector and genetic algorithm. As a reference of wavelength selection for PLSR, the loading vector has the advantage over the correlation plot since the former is based on multivariate model whereas the latter, on univariate model. Wavelength selection by the first loading vector analysis requires shorter computation time than that by genetic algorithm and needs not smoothing.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1125-1125
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• 2001

Micro-scale test methods are producing small-sample size where the conventional physical and chemical tests can not be used (high standard deviation, uncertain sampling conditions, low repeatability). Different small-scale test methods were developed recently for determination of physico-chemical, functional, rheological properties of wheat or wheat dough using miniaturized instruments with sophisticated sample preparation/handling and mechanics (RVA, 2 g mixograph, micro-Z-arm mixer, small-scale noodle maker, micro-baking method etc.). The small-scale methodologies can be used as basic research tools or as technology supported measurements and can be also essential in the early selection for quality traits in breeding programs. The milling as a sample preparation step is essential procedure providing good quality flour or semolina samples from small amount of grain (5-10 g) in a reproducible and reliable way. The aim of present study was to use NIR as quality control tool, and to evaluate the recently developed and manufactured micro-scale lab mill (FQC-2000) produced by Inter-Labor Co. Ltd., Hungary. The milling characteristics of the new instrument were compared to other laboratory mills and the effects of milling action on the chemical composition of fractions were analysed. The fractions were tested with both chemical and near infrared spectroscopic methods. The micro-scale milling resulted significantly different yields, particle size distributions and different fractions from compositional point of view. The near infrared spectra were sensitive enough to distinguish the fractions obtained by different milling procedures. Quantitative NIR calibration equations were developed and tested in order to measure the chemical composition of characteristic milling fractions. Special qualification procedure the PQS (Polar Qualification System) method was used for detecting the differences between fractions obtained by macro and micro-milling procedures. The results and the limitations of PQS method in this application will be discussed.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3102-3102
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• 2001

Constituents of several .representative seaweeds, such as wakame Undaria pinnatifida; hijikia Hizikia fusifome; and kombu Laminaria japonica, were found to have fairly large reaction rates determined by quenching experiments of emission spectra in the near-infrared region (1max: 1270 nm) from singlet oxygen (102). Emission spectra of singlet oxygen generated from an aqueous solution of Rose Bengal under irradiation with a green laser (330 nm) were measured by a near-infrared (NIR) emission spectrometer constructed in our laboratory. The quenching experiments were as follows: Intensities of emission spectra were measured in the absence (I0) and in the presence of the seaweed constituents (I): Ratios of I0/I were plotted against every concentration of the quenchers (Stern-Volmer plots) which gives a straight line. The slope of each line gives a kqt value which gives a quenching constant kq value (an antioxidative constant against singlet oxygen) when the t value (half-life time of singlet oxygen in the solvent used) was given. The determined reaction rates are between 103-105 (g/l)-ls-1; the larger ones are as large as that of ascorbic acid, 8.4 ${\times}$ 104 (g/1)-ls-1. Most of these seaweed constituents also showed antioxidative activity against auto-oxidation and superoxide as well as their immunological enhancing activity. These results suggest a possibility that dietary fibers which are supposed to prevent the large-intestine cancer by their physical properties may prevent the cancer, at least in parts, by their chemical, antioxidative activity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.625-634
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• 2016

A full digital receiving active phased array antenna generates final receiving beams by digital beam forming of received digital signals in element-level that makes difficult to use typical near-field measurement method. Thus in this paper, a modified near-field measurement method which is suitable for full digital receiving active phased array antenna is proposed. Also the measured results of receiving beam pattern and G/T using developed L-band full digital receiving active phased array antenna are shown for the verification of proposed method.