• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.774-780
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• 1998

For the stabilization of the spinel structured $LiMn_2O_4$, a fraction of manganese was substituted with various metals such as Mg, Fe, V, W, Cr, Mo with Mn that had a similar ionic radii ($LiM_xMn_{2-x}O_4(0.05{\leq}x{\leq}0.02)$). The $LiM_xMn_{2-x}O_4$ showed a substantial improvement as lower capacity loss than that of the spinel structured $LiMn_2O_4$ when it was used as a cathode material. And with the partial substitution, the chemical diffusion coefficient for $LiMg_{0.05}Mn_{1.9}O_4$ and $LiCr_{0.1}Mn_{1.9}O_4$ was increased by and order of magnitude compared to that of the $LiMn_2O_4$ with spinel structure. The results showed that significant improvement can be made on the electrochemical characteristics as the structure of the $LiMn_2O_4$ electrode material was stabilized by the partial substitution.

• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.565-577
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• 2019

The purpose of this study was to understand the factors influencing the decline and the patterns of changes in Abies nephrolepis populations on Mt. Seorak. We installed permanent quadrats in the areas of the Gwittagicheongbong (peak), Gwanmoneungseon (ridge), and the Seorak Falls and have monitored the community structure, population dynamics, radial growth, and vitality in the quadrats since 2009. Excluding the Seorak Falls, the three research sites showed a three-layer structure in which the low-tree layer forms the canopy. Major tree species were Khingan fir, Korean arborvitae, Mongolian oak, Erman's birch, and Korean maple. The significance of Khingan fir in Seorak Falls decreased from 45.3% in 2009 to 36.8% in 2018. The number of shoots ($DBH{\geq}5cm$) was highest at 1,800 individuals/ha and 1,700 individuals/ha at the Gwittagicheongbong 2 and the Gwanmoneungseon, respectively. The mortality rates over the past 10 years were very high, at 38.3% and 35.3%, respectively, in the Gwittagicheongbong 1 and Seorak Falls. The most stable inverse J-shaped distribution in the Gwittagicheongbong 1 area was shown in the size-frequency distribution of the Khingan fir populations. The average annual ring growth of the Khingan fir was 0.96 ~ 1.73 mm/year, and the ring growth tended to decrease in the areas of Gwittagicheongbong 1, Gwanmoneungseon, and Seorak Falls, where the vitality was low. If the monitoring process continues, it will be possible to obtain basic data for the conservation and management of subalpine vegetation.

• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.45-56
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• 2021

As the utilization of the underground space is activated, deep excavation of ground has been conducted for the installation of underground structures, the earth retaining wall has widely used to minimize deformation of the excavated ground. In particular, as deep excavation is actively progressing in an urban area where structures are concentrated, methods to minimize the deformation of wall have been devised to prevent damage to the structure adjacent to the wall, and one of these methods is the pre-loading method. This method is a method of suppressing the deformation of wall by actively applying a load on the strut to be installed in wall, and research on this method has been conducted recently. However, although related studies have been actively conducted, the management standard for the pre-loading of bracing has not been clearly presented until now. In addition, since the working force in the strut may increase depending on the depth of excavation or the soil condition of the backfill, the magnitude of the pre-loading that can be applied to the brace may decrease. Nevertheless, the magnitude of the pre-loading (more than 50% of the working load) proposed by the previous research results has been uniformly applied to the strut. In this study, 3D finite element analysis was performed to evaluate the application range of the pre-loading of H-beam strut according to the soil conditions of backfill. As a result of the analysis, it was found that there is a very high possibility that a problem may occur in the stability of the structure of strut due to the earth pressure and the pre-loading when the soil condition is weak and deep excavation proceeds. And it was found that the application range of the pre-loading was 5%~70% of the working load in strut.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.623-626
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• 2011

Various poly(amic acid)s were synthesized from PMDA/BPDA/p-PDA/ODA with different mole ratios and effectively converted into 4-component polyimide films by thermal imidization. The chemical structures and thermo-mechanical properties of polyimide films were examined using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analyzer (TGA), thermo-mechanical analyzer (TMA), dynamic mechanical analyzer (DMA) and universal tensile machine (UTM). The tensile strength, modulus, and thermal properties of polyimides films increased with the amount of rigid PMDA and p-PDA, while the elongation and moisture absorption of polyimide films increased with the amount of flexible BPDA and ODA. One of 4-component polyimide films exhibited a similar coefficient of thermal expansion (CTE) value to that of copper when it was composed of PMDA : BPDA : p-PDA : ODA with the ratio of 5 : 5 : 4 : 6. Thus, this polyimide film could be useful for a base film for flexible copper clad laminates (FCCL) of flexible printed circuit boards.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.574-581
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• 2022

Nanofibers comprising reduced graphene oxide (rGO) and Mo₂C/Mo₂N nanoparticles (Mo₂C/Mo₂N rGO NFs) were prepared for a functional interlayer of Li-S batteries (LSBs). The well-dispersed Mo₂C and Mo₂N nanoparticles in the nanofiber structure served as active polar sites for efficient immobilization of dissolved lithium polysulfide. The rGO nanosheets in the structure also provide conductive channels for fast ion/electron transport during charging-discharging and ensured reuse of lithium polysulfide during redox reactions through a fast charge transfer process. As a result, the cell assembled with Mo₂C/Mo₂N rGO NFs-coated separator and pure sulfur electrode (70 wt% of sulfur content and 2.1 mg cm^-2 of sulfur loading) showed a stable discharge capacity of 476 mA h g^-1 after 400 charge-discharge cycles at 0.1 C. Furthermore, it exhibited a discharge capacity of 574 mA h g^-1 even at a high current density of 1.0 C. Therefore, we believe that the proposed unique nanostructure synthesis strategy could provide new insights into the development of sustainable and highly conductive polar materials as functional interlayers for high performance LSBs.

• Korean Journal of Heritage: History & Science
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• v.54 no.1
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• pp.52-69
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• 2021

The transcriptions of Buddhist sutra in the Goryeo Dynasty are more elaborate and splendid than those of any other period and occupy a very important position in Korean bibliography. Among them, the transcriptions made on indigo paper show decorative features that represent the dignity and quality that nobles would have preferred. Particularly, during the Goryeo Dynasty, a large number of transcriptions were made on indigo paper, often in hand-scrolled and folded forms. If flexibility was not guaranteed, the hand-scrolled form caused inconvenience and damage when handling the transcription because of the structural limitations of the material that is rolled up and opened. It was possible to overcome these shortcomings by changing from the hand-scrolled to the folded form to obtain convenience and structural stability. The folded form of the transcription utilizes the same principle as the folding screen, so it is a structure that can be folded and unfolded, and it is made by connecting parts at regularly spaced intervals. No matter how small the transcription is, if it is made of thin paper, it is difficult to handle it and to maintain its shape and structure. For this reason, the folded transcription was usually made of thick paper to support the structure, and the cover was made thicker than the inner part to protect the contents. In other words, the forded form was generally manufactured to suit the characteristics of maintaining strength by making the paper thick. Because a large amount of indigo paper was needed to make this type of transcription, it is assumed that there were craftsmen who were in charge only of dark dyeing the papers. Usually, paper dyeing requires much more dye than silk dyeing, and dyeing dozens of times would be required to obtain the deep indigo color of the base of the transcription of Buddhist sutra in the Goryeo Dynasty. Unfortunately, there is no record of the Goryeo Dynasty's indigo blue paper manufacturing technique, and the craftsmen who made indigo paper no longer remain, so no one knows the exact method of making indigo paper. Recently, Hanji artisans, natural dyers, and conservators attempted to restore the Goryeo Dynasty's indigo paper, but the texture and deep colors found in the relics could not be reproduced. This study introduces the process of restoring indigo paper in the Goryeo Dynasty through collaboration between dyeing artisans, Hanji artisans, and conservators for conservation of the transcription of Buddhist sutra in the late Goryeo dynasty, yielding a suggested method of making indigo paper.

• The Korean Journal of Air & Space Law and Policy
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• v.27 no.2
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• pp.29-65
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• 2012

Der neue strukturelle Ansatz der Kommbination eines Rahmen$\ddot{u}$bereinkommens und eines ausr$\ddot{u}$stungsspezifischen Sonderprotokolls bedingt einen neuen organisatorischen Anstz f$\ddot{u}$r die Zusammenarbeit zwischen internationalen Organisationen bei der Schaffung von internationalem Einheitsprivatrecht. So haben hier zwei internationale Organisationen gemeinsam die Verantwortung f$\ddot{u}$r einmultilaterales $\ddot{U}$bereinkommen $\ddot{u}$bernommen: auf der einen Seite UNIDROIT als die internationale Organisation, die generell f$\ddot{u}$r die Vereinheitlichung des Privatrechts kompetent ist; auf der anderen Seite ICAO als die f$\ddot{u}$r die private Luftfahrt zust$\ddot{a}$ndige internationale Organisation. Dieses neue, f$\ddot{u}$r die Luftfahrzeugausr$\ddot{u}$stung praktizierte organisatorische Modell eines joint venture zweier internationaler Organisation bei der Einheitsrechtsetzung, namlich die Betreuung eines allgemeinen privatrechtsvereinheitlichenden Rahmens$\ddot{u}$bereinkommens durch UNIDROIT und die Wahrnehmung der sektorspezifischen Belange in einem ausr$\ddot{u}$stungsspesifischen Sonderprotokoll durch die jeweils zust$\ddot{a}$ndige internationale Spezialorganisation, hat bereits f$\ddot{u}$r die Sektoren der Eisenbahn- und Weltraumausrustung Schule gemacht. Das in Kapstadt beschlossene v$\ddot{o}$lkervertragliche Regelungswerk hat erstmals ein einheitsrechtliches - grunds$\ddot{a}$atzlich weltweite Geltung anstrebendes - Sicherungsrecht geschafen. Dies kann f$\ddot{u}$r die Sachenrechtsintergration einen $\ddot{a}$hnlichen Durchbruch bedeuten, wis das Wiener UN-kaufrechts$\ddot{u}$bereinkommen von 1980 f$\ddot{u}$r das Schuldvertragsrecht. Voraussetzung daf$\ddot{u}$r ist allerdings die juristische Qualit$\ddot{a}$t und Praxisgerechtigkeit des Regelungswerkes und - insbesondere - das Funktionieren des Registersystems. Von wesentlicher Bedeutung f$\ddot{u}$r den Erfolg des $\ddot{U}$bereinkkommens wird auchsein, ob es Rechtssicherheit zu gew$\ddot{a}$hrleisten vermag.

• Journal of the Korean Geosynthetics Society
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• v.7 no.2
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• pp.1-5
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• 2008

The differential settlement on ordinary concrete buildings and paved roads are often occurred and which caused the failure of structure. The grouting method can be used for correcting the settlement of the structure. However, the grouting method has a disadvantage like that it takes a long time period to get a desired strength, and it is not a continuous in the phase of reinforced effect. In this paper, as an injecting material called GPCON to complement disadvantage, it is estimated about the characteristic that has a high-density expansion. With the changing of ground conditions and amount of injection, the change of physical strength on compression, the stability against chemical material are studied through the filming of SEM. The physical strength with compression is developed to high strength due to mixing with other material. It is not react with most of the material on chemical conditions except the component of alcohol. Through the SEM test. it is confirmed that the strength of material was increased as formation is being densified.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.35-45
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• 2008

Realtime visibility measurement using camera is a new method which can collect some realtime visibility data similar to those of the human eyes, and can replace the existing methods using the expensive optical equipment. There have been a few attempts to measure visibility by extracting depth and three-dimensional structure under bad weather conditions. However, if there are many movements of objects in the image, these approaches seem to be inappropriate. In addition, the realtime visibility measurement will require a relatively simple and fast processing. Typically the contrast degrades exponentially in the bad weather. Therefore, in this paper we propose an easy and quick method that extract contrast from images using a moving area filter and measure visibility by mathematically modelling of the relationship between image contrast and visibility. The moving area filter is used for removing the area of the sky and moving objects that affect visibility measurement on images. The method proposed here can make possible not only realtime visibility measurement from images taken by CCD cameras, but also steady visibility measurement by using the moving area filter in case of much traffic on the road.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.137-147
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• 2013

It is essential to understand the hydraulic characteristics of rivers for increasing flood-control capacity and operating hydraulic structures efficiently. Multi-dimensional models can be the proper measures to obtain the detailed information on the hydraulic characteristics of rivers. But huge amount of data and time-consuming work have been the obstacle for applying multi-dimensional models. In this study, simulation technique with multi-dimensional model(EFDC), coupled with COSFIM and FLDWAV, has been developed and applied to the real river system for verification. Developed technique can offers spatial and grid unit information as well as line and section unit information from 1-D modeling. It is considered that the coupling simulation technique can provide useful hydraulic information for river management and treatment.