• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1275-1284
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• 2022

This study provides an investigating the electrolyte reaction characteristics during thermal runaway of a lithium-ion battery(LIB). Dimethyl carbonate(DMC) is known as the main substance that makes up the electrolyte. The mono-molecular decomposition characteristics of DMC were derived through numerical analysis. Cobalt oxide can release oxygen under high temperature conditions. Also, DMC is converted to CH₄, H₂, CO, and CO₂. Especially, it was found that the decomposition of the DMC begins at a temperature range of 340-350℃, which dramatically increases the internal pressure of the LIB. In the by-products gases, the molar ratio of CO and CO₂ changed according to the molecular structure of DMC and temperature conditions. The correlation of the [CO]/[CO₂] ratio according to the temperature during thermal runaway was derived, and the characteristics of the reaction temperature could be estimated using the molar ratio as an indicator. In addition, the oxidation and decomposition characteristics of DMC according to the residence time for each temperature were estimated. When DMC is exposed to low temperature for a long time, both oxidation and decomposition may occur. There is possibility of not only increasing the internal pressure of the LIB, but also promoting thermal runaway. In this study, internal environment of LIB was identified and the reaction characteristics between the active materials of the cathode and electrolyte were investigated.

• Korean Journal of Ichthyology
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• v.18 no.1
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• pp.27-35
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• 2006

During spawning season of female in a Korean oily bitterling, Acheilognathus koreensis, the ventral region near the base of the pectoral fin becomes to be protruded outward of body and enlarged. This ventral process consists of both organs as rectum (vent) and inner ovipositor. The rectum consists of mucosa, lamina propria-submucosa, muscularis, and squamous epithelial layer (peritoneum=serosa) surrounding them. The mucosa contains numerous mucous cells meaning acid mucopolysaccharides in nature. The inner ovipositor is similar to that of the rectum, but the mucosa have no mucous cell, unlike that of the rectum. Whereas, the outer ovipositor has a straight and long tube which are not connected with the ventral process any more. The outer ovipositor was similar to the structure of the inner ovipositor in the ventral process. However, the outer ovipositor has no muscularis, and consists of three layers: mucosa, lamina propria-submucoa, and squamous epithelia. The outer ovipositor without the muscularis seems serves as a tube that eggs discharged from the outer ovipositor allow to send inside mussel, unlike that of the inner ovipositor performing rhythmic contractions of the layers of the muscularies for propelling to the matured oocytes to the outer ovipositor.

• Geophysics and Geophysical Exploration
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• v.17 no.1
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• pp.28-33
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• 2014

We investigate the spatial distribution of highly conductive layer using the one-dimensional inversions of the new magnetotelluric (MT) measurements obtained at the mid-mountain (400 ~ 900 m in elevation) western area of Jeju Island and the previous MT data over Jeju Island, Korea. The conductive layer indicates the sedimentary layer comprised of Seoguipo Fomation and U Formation. There is a definite positive correlation between the top of conductive layer and the earth surface in elevation. On the contrary, the bottom of conductive layer has a negative correlation with the surface elevation. In other words, the conductive layer has a shape of convex lens, which is thickest in the central part. The basement beneath the conductive layer could be concave in the central part of Jeju Island. A kriging considering the correlation between the layer boundary and the surface elevation provides a reliable geoelectric structure model of Jeju Island. However, further studies, i.e. three-dimensional modeling and interpretation integrated with other geophysical or logging data, are required to reveal the possible presence of three-dimensional conductive body near the subsurface vent of Mt. Halla and the causes of the bias in the depths of layer estimated from MT and core log data.

• The Journal of the Petrological Society of Korea
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• v.6 no.2
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• pp.96-110
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• 1997

The Wondong Caldera, formed by the voluminous eruption of the rhyolitic ashflows of the Wondong Tuff which is about 1,550 m thick at the intracaldera and 550 m at the outflow, is a resurgent caldera which shows a dome structure on the central exposure of the caldera. The Wondong caldera volcanism eviscerated the magma chamber by a series of explosive eruptions during which rhyolitic magma was ejected, as small fallouts and voluminous ash-flows, to form the Wondong Tuff. The explosive eruptions began with ash-falls, progressed through pumice-falls and transmitted ash-flows. During the ash-flow phase the initial central vent eruption transmitted into late ring-fissure eruption which accompanied with caldera collapse. Contemporaneous collapse of the roop of the chamber resulted in the formation of the Wondong Caldera, a subcircular depression subsiding about 1,930 deep. Following the collapse, quartz porphyry was intruded as ring dykes along the ring fracture near the southwestern caldera rim. Subsequently the central part of the caldera floor began to be uplifted into a circular resurgent dome by the rising of residual magma. Concurrent with the resurgent doming, the volcaniclastic sediments of Hwajeri Formation were accumulated in the caldera moat and then rhyodacite lava erupted from the initial central resurgent dome and another ash-flow tuff from the northern ring fracture. After the sedimentation, the find-grained granodiorite was intruded as an arc along the eastern ring fracture of the caldera. Finally in the central part, the resurgent magma was emplaced as a hornblende biotite granite stock that formed the central dome.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.428-436
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• 2012

This study aimed to develop the multi-span plastic greenhouse which is suitable for tomato cultivation and is safe against climatic disasters such as typhoon or heavy snow. The width and heights of eaves and ridge of newly developed tomato greenhouse are 7, 4.5 and 6.5 m, respectively. The width is the same but the eaves and ridge heights are 1.8 and 2 m higher than conventional 1-2 W greenhouses, respectively. Cross beam has been designed as a truss structure so it can sustain loads of tomato and equipment. Tomato greenhouse has been designed according to climatic disaster preventing design standard maintaining the high height. In other words, the material dimensions and interval of materials including column and rafter have been set to stand against $40m{\cdot}s^{-1}$ of wind and 40 cm of snow. Tomato greenhouse has been equipped with rack-pinion type roof vents which have been used in glass greenhouse in order to prevent excessive rise in air temperature. This vent type is different from that of 1-2 W type greenhouse which is made by rolling up and down the vinyl at upper part of column. Roof vents are installed at ridge, and thus external air inflow and natural ventilation are maximized. As the height increases, heating cost increase as well and, therefore, tomato greenhouse has been equipped with multi-layered thermal curtain, of which thermo-keeping is excellent, to prevent heat from escaping.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.80-88
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• 2016

A fire station and scuba have operated filling facilities for respiratory high-pressure cylinder without getting authority or reporting according to High-Pressure Gas Safety Control Act. They need facility improvement and special management to make provision for the time of accident during filling process. The Government have strived to correct illegal operations and suggested an alternative, establishing and operating the safety cabinet. It insures a safety being distance from danger caused by overpressure and a safety provoked by the protective wall equals or superiors. The safety cabinet is required to have an internal structure that smoothly distribute overpressure at the time of rupture. Plus, it needs to minimize fragments. It is also equipped with the performance of protective wall that makes overpressure to outside vent on the place where there is no person (top or bottom). This study calculated the consequence of physical explosion damage and built a prototype of safety cabinet. In addition, through the gas burst test, it derives for the ways to mitigate the physical explosion damage.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.468-475
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• 2019

An end-line flame arrester allows free venting in combination with flame protection for vertical vent applications. End-line flame arresters are employed in various fields, especially in shipping. In flame arresters, springs are essential parts because the spring load and the spring's elasticity determine the hood opening moment. In addition, the spring has to work under a high-temperature condition because of the burning gas flame. Therefore, it is necessary to analyze the mechanical load and elasticity of the spring when the flame starts to appear. Based on simulations of the working process of a specific end-line flame arrester, a thermal and structural analysis of the spring is performed. A three-dimensional model of a burned spring is built using computational fluid dynamics (CFD) simulation. Results of the CFD analysis are input into a finite element method simulation to analyze the spring structure. The research team focused on three cases of spring loads: 43, 93, and 56 kg, correspondingly, at 150 mm of spring deflection. Consequently, the spring load was reduced by 10 kg after 5 min under a $1,000^{\circ}C$ heat condition. The simulation results can be used to predict and estimate the spring's load and elasticity at the burning time variation. Moreover, the obtained outcome can provide the industry with references to optimize the design of the spring as well as that of the flame arrester.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.619-630
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• 2018

The purpose of this study is to investigate the existence of faults and intrusive rocks in the volcanic rock mass of Ulleung-do using magnetic anomalies. The magnetic survey data show that basaltic (mafic) rocks have high magnetic anomalies and that trachytic (felsic) rocks have low magnetic anomalies, implying that the anomaly distributions can be used to distinguish between different volcanic rock types that may be covered by regolith (such as alluvial and colluvial deposits) and other sedimentary layers. Our results show that basaltic rocks are not present within the Nari caldera. However, outside the caldera, the occurrence of high magnetic anomaly values of >$1,000{\gamma}$ is presumed to reflect the existence of basaltic craters or volcanic vents that formed prior to the eruption of the trachytic rocks. In particular, the area with anomaly values of >$1,000{\gamma}$ in the vicinity of Namyang-ri, southwest of Ulleung-do, is interpreted as having a high probability of hosting a crater and vent originating from mafic volcanism.

• Korean Journal of Ichthyology
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• v.6 no.2
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• pp.132-159
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• 1994

The taxonomic revision of the family Congridae was made based on the specimens collected from the south-western coasts of the Korea from June 1988 to Oct. 1993. The family Congridae was classified into 8 species belonging to 6 genera. based on the external and internal morphological characters : Anago anago, Ariosoma anagodies, Ariosoma shiroanago shiroanago, Conger myriaster, Conger japonicus, Gnathophis nystromi nystromi, Rhechias retrotincta and Uroconger lepturus. Among the species reported as the congrid eels from Korea until now, four species were transferred into different generic or specific name Conger flavirostris into Ariosoma anagoides ; Astroconger myriaster into Conger myriaster ; Congrina retrotincta into Rhechias retrotincta and Rhynchocymba nystromi into Gnathophis nystromi nystromi. A Korean congrid eel, Ariosoma shiroanago shiroanago, was reported for first time in Korea. Intergeneric characters of the family Congridae were the form of the lateralline scales, the state of the tip of tail, the segmented state of the dorsal and anal fin rays, the existance of the supraoccipital bone and of lateral ethmoid process of the skull, the origin of dorsal fin and the forms of upper labial flange. The interspecific classification was made according to the characters such as the numbers of sensory pores of head part and in front of vent, teeth rows and numbers of upper and lower jaw, the numbers of vertebrae, the body color, the shapes of the head part, the color of intestine, the size of eye, the structure of air bladder and the number of branchiostegal rays. A new key on the taxonomical characteristics to the genera and species of the family Congridae has been estabilished and their distribution in Korea is described.