• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.167-174
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• 2016

The Korean distribution line currently consists of overhead ground wires (OHGW), overhead distribution lines, neutral wires (NW), and messenger wires (MW). The MW is installed under the NW. The lightning protection system in Korea is focused on OHGW and lightning arrester and the MW are not considered. Therefore, this paper proposes the applicability of MW for purpose of lightning protection. For this, we analyzed the effects of lightning overvoltage according to the existence of OHGW and MW and the grounding conditions of the MW in the Korean distribution system. The grounding conditions of the MW that we took into consideration were the common or separate grounding of the MW and NW. The analysis based on the equivalent circuit of the distribution pole at each condition was performed. The distribution lines and lightning were modeled using the Electromagnetic Transients Program (EMTP). For each of the installation conditions of the OHGW and MW, the various lightning conditions were simulated and analyzed for both direct and indirect lightning. The simulation results showed that, if the OHGW was not installed in the Korean distribution system, the lightning overvoltage could be reduced by the common grounding of the MW and NW.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.241-245
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• 2011

In this paper, when photovoltaic (PV) systems are connected to power distribution system, most effective capacity and connected-point of PV system are presented considering power distribution system reliability. The reliability model of PV system is presented considering the duration of sunshine. Also the model of time-varying load and reliability test system bus2 model are used. To simulate the effects of PV system, various cases are selected; (1) base case which is no connection of PV system to power distribution system when faults are occurred, (2) 3MW case which is 3[MW] connection of PV system (3) 4[MW] case, and (4) 20[MW] case which is 20[MW] connection of PV system to the bus of power distribution system. The capacity limit of connected PV system is settled to 14[MW] for all cases except case 4. The reliability for residential, general, industrial, and educational customer is evaluated.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.163-168
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• 2014

In this paper, when photovoltaic systems are connected to distribution system, most effective capacity and location of PV system are studied considering customer interruption costs of power distribution system. The reliability model of PV system considering the duration of sunshine, the model of time-varying load and Roy Billinton test system (bus2 model) are used. To simulate the effects of PV system, various cases are selected; (1) base case which is no connection of PV system to power distribution system when faults are occurred, (2) 3MW case which is 3[MW] connection of PV system (3) 4[MW] case, and (4) 20[MW] case which is 20[MW] connection of PV system to the bus of power distribution system. The capacity limit of connected PV system is settled to 14[MW] for all cases except case 4. The reliability and customer interruption costs for residential, general, industrial, and educational customer is evaluated.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.4
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• pp.313-317
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• 2006

To prepare oligouronic acids from high-molecular-weight alginates, sea tangle (Laminaria japonica) alginates were hydrolyzed at various pHs for 1 hr at 80$^{\circ}C$. The effects of hydrolysis pH (HpH) on the average molecular weight (AMW) and MW distribution ratios (DRs) in the hydrolyzed alginates were investigated. As HpH decreased, the DRs of the alginates with MW>500 kDa and MW=300-500 kDa decreased exponentially, while it increased exponentially for MW<50 kDa. For MW=100-300 kDa, DR increased exponentially as HpH fell from 5.0 to 3.5, and then decreased exponentially. Similarly, for MW=50-100 kDa, DR increased exponentially as HpH increased to 1.0 from 5.0, and then decreased exponentially. As HpH decreased, the MW cutoff size and AMW of alginates fraction with the highest DR were decreased. For HpH 4.5 and 5.0, the MW cutoff size with the highest DRs was MW=300-500 kDa; the DRs were 28.9 and 32.6%, respectively; and the AMW of both was about 400 kDa, for HpH 3.5 and 4.0, the cutoff size was MW=100-300 kDa; the DRs were about 28%: and the AMWs were both about 200 kDa. For HpH 3.0, the cutoff size was MW=50-100; the DR was 29.0%; and the AMW was 73 kDa. For HpH values below 2.0, the MW cutoff size with the highest DRs was MW<50 kDa, and all of the AMWs were below 28 kDa.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.4
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• pp.187-192
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• 2007

To prepare oligouronic acids from high-molecular-weight alginates prepared from sea tangle (Laminaria japonica), the alginates were hydrolyzed at various temperatures for 1 hr at pH 5.0. The effects of hydrolysis temperature $(H_{Temp})$ on the average molecular weight (AMW) and distribution ratio of MW (DR) in the hydrolyzed alginates were investigated. As $(H_{Temp})$ increased, the AMW of the alginates decreased exponentially; in addition the DR of the alginates with MW>500 kDa decreased exponentially, while the DR of those with MW=50-100 and MW<50 kDa increased exponentially. For the alginates with MW=300-500 and MW=100-300 kDa the DR increased exponentially until $H_{Temp}$ reached $80^{\circ}C$, and then decreased exponentially at above $80^{\circ}C$. AS $H_{Temp}$ increased, the MW cutoff size and AMW Of the alginates fraction With the highest DR both decreased. For $H_{Temp}<60^{\circ}C$, the MW cutoff size with the highest DR was MW>500 kDa; the DR was 39-67% and the AMW 1,000-1,300 kDa. For $H_{Temp}$ $80^{\circ}C$, the MW cutoff size with the highest DR was MW=300-500 kDa and the DR was about 33% and the AMW about 400 kDa. For $H_{Temp}\;100-121^{\circ}C$, the MW cutoff size with the highest DRs was MW=50-100 kDa, with a DR of 39-44% and an AMW of 70-80 kDa.

• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.113-117
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• 2005

To prepare oligouronic acids from high-molecular-weight alginates, sea tangle Laminaria japonicus alginates were hydrolyzed at $80^{\circ}C$ for various hydrolysis times (HT). The effects of hydrolysis time on the distribution ratios (DR) of the molecular weights (MW) of the hydrolyzed alginates were in-vestigated. As HT increased, the DR of the alginates with MW>500 kDa decreased ex-ponentially, while those with MW=50-100 kDa or MW<50 kDa increased exponentially. For MW=300-500 kDa, DR increased exponentially until HT reached 60 min, and then decreased exponentially. Similarly, for MW=100-300 kDa, DR increased exponentially until HT reached 90 min, and then decreased.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.33.3-34
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• 2020

The Milky Way (MW) and other systems including M31 and Cen A have flattened structures of their satellites (Disk of Satellites, DoS). Such structures are rare in simulations under the ΛCDM paradigm. DoS is known to depend mainly on 1) the alignment of satellite orbits and 2) the degree of central concentration of satellites. In this work, we examine quantitatively how these two parameters affect the flatness of a system. We find that the MW-like DoS is rare in IllustrisTNG100 simulation because its two parameters are out of the 1-s range and furthermore the MW has a structure more flattened than the other systems having similar parameters. Besides, we propose a new criterion for the MW-like systems superseding the conventional ones such as major-minor axis ratio of the MW's DoS with a value of 0.183. Each satellite system has a specific orbital combination and thus has a particular distribution of its parameters (and thus flatness). The median of the distribution is set as the representative value of each system. And the representative value of the MW can be used as a new criterion for classifying the MW-like DoS. We reconstruct the orbital combination of the observed MW satellites using GAIA DR2 data and find the systems in the simulation that have representative values similar to the new criterion from the reconstructed MW system. This allows us a new interpretation on the rarity of MW-like DoS in cosmological simulations.

• Journal of the Korean Wood Science and Technology
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• v.45 no.4
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• pp.471-481
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• 2017

As the molecular weight (MW) of urea-formaldehyde (UF) resins had a great impact on their properties, this work was conducted to study effect of analytical parameters of gel permeation chromatography (GPC) on the MW measurement of UF resins. GPC parameters such as flow rate, column, detector temperature, and sample injection temperature were selected to compare number-average molecular weight (Mn), weight-average molecular weight (Mw), molecular weight distribution (MWD) and polydispersity index (PDI) of two UF resins with different viscosities. As expected, UF resin with higher viscosity resulted in greater Mn and Mw than those of low viscosity UF resin. When the flow rate increased, both Mn and Mw of UF resins decreased and MWD became narrower. By contrast, both Mn and Mw increased and MWD became wide when the column, detector, and sample injection temperature increased. The column, detector, and sample injection temperature of $50^{\circ}C$ at a flow rate of $0.5m{\ell}/min$ resulted in the highest MW and broadest MWD for the GPC analysis. These results suggest that the apparent molecular size or a hydrodynamic radius of UF resin molecules dissolved in the mobile phase affect to Mn, Mw and MWD.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.72.3-73
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• 2017

The spatial distribution of sub-halos in a large host halo is usually described as isotropic in the ${\Lambda}CDM$ cosmology. Recent observations, however, show that satellite galaxies around massive galaxies are often located within a preferred plane. In order to understand the origin of such planar alignment, we investigate the spatial distribution of sub-halos around their hosts by using the hydrodynamic cosmological simulation, Illustris. In particular, we analyze the systems resembling the Milky Way (MW) and its satellites, i.e. consisting of MW-sized central galaxy and its at least 11 satellites. The result shows that ~10 % of MW-like systems have the anisotropic satellite galaxy distribution at z = 0. The satellites that are accreted more recently tend to form a flattened structure more frequently, indicating a link of satellite distribution to the surrounding environment. We discuss the physical origin of the anisotropic satellite distribution from the viewpoint of the ${\Lambda}CDM$ paradigm.

• Journal of Chest Surgery
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• v.19 no.4
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• pp.750-759
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• 1986

Spontaneous pneumothorax is usually seen in young adult male. And typically, the patient is a tall, thin, 20- to 30-year-old male. Usually the pneumothorax results from rupture of a pulmonary bleb. Author reviewed 66 cases of spontaneous pneumothorax experienced in the Dept. of Thoracic & Cardiovascular Surgery, Pusan National University Hospital, since Jan., 1980 to Aug., 1986. The clinical data were summarized as follows: 1. The age distribution of spontaneous pneumothorax: 17 to 34 years old and mean age was 25.3 years. 2. The sex distribution of spontaneous pneumothorax: 52 in men, 14 in women and the ratio was 3.7:1. 3. Chest dimension in male patients: Maximum posteroanterior distance [MPA], MPA/Maximum width [MW]: Significantly smaller than control group. Distance from second to tenth rib on left [L2-10], Distance from second rib on right to diaphragm [R2-D], R2-D/MW: Significantly larger than control group. 4. Chest dimension in female patients: MPA, MW: Significantly smaller than control group. Distance from second rib on left to diaphragm [L2-D], Distance from second to tenth rib on right [R2-10], R2-D, L2-10/MW, L2-D/MW, R2-10/MW, R2-D/MW: Significantly larger than control group.