• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.263-273
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• 1994

Titanium powder prepared by dehydrogenating the titanium hydride which is synthesized by reacting Ti-sponge (99.67%) with hydrogen using the self-propagating high-temperature synthesis method. In the synthesis of titanium hydride, the particle size of the product was found dependent on the amount of hydrogen incorporated into the titanium such that the particle size of titanium hydride decreased with increasing hydrogen pressure and after-burn time. In the dehydrogenation process, as the dehydrogenation time increase, the particle size of titanium powder increased due to partial melting and sintering of titanium particles.

• Congress of the korean instutite of fire investigation
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• 2011.04a
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• pp.137-160
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• 2011

본 사고분석을 통해 154 kV 절연부싱에서의 폭발사고에 대한 원인을 규명하였다. 결과적으로, 절연부싱의 사양은 국제표준에 적합하였다. 사고당일 기록된 자료에 의하면 R상과 S상에서 거의 동시에 지락사고가 발생하였으며, 지락지속시간은 약 75 ms로써 사고의 영향을 준 시간은 약 67 ms인 것으로 나타났다. R상은 아크에 의한 탄화 흔적, S상은 아크에 의한 탄화흔적과 외부열에 의한 탄화흔적, T상은 외부열에 의한 탄화흔적, 용융흔적은 R상과 S상의 케이블접속부와 플랜지에서 각각 발생하였다. S상의 절연부싱을 이용하여 탄화패턴 중 아크에 의한 것과 일반 열에 의한 것을 분류하여 연면방전이 발생한 것을 입증하였다. 사고추정 시나리오는 현장조사과정에서 나타난 현상과 목격자 진술, 사고원인 분석자료 등을 토대로 하여 작성되었다. 따라서 사고추정을 통해 분석된 자료는 아크생성단계, 열폭주 단계, 폭발단계, 화재단계로 구성하였다. 사고원인 가능성은 사고의 원인, 형태, 영향을 통해 나타난 연결고리를 검토하여 가능성이 낮은 부분을 배제하는 방식으로 진행되었다. 절연부싱의 사고원인은 표면의 오염물질 부착 가능성이 가장 높았다. 이를 근거로 하여 제조, 시공, 관리적 측면에서의 방지대책을 고려하는 것이 바람직할 것으로 판단된다.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.1
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• pp.39-47
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• 2021

Compared to conventional method, if metal framework of removable partial denture is fabricated by selective laser melting, various laboratory works are omitted, saving time and simplifying the process. In addition, metal framework with homogeneous density can be obtained, expecting excellent mechanical properties, especially resistance to fatigue fracture. In these cases, impression were taken using conventional methods in partial edentulous patients, master casts were fabricated and scanned to obtain digital data. After designing the metal frameworks on the scanned data, removable partial dentures were fabricated using selective laser melting methods. Through these procedure, satisfactory outcomes were achieved both in functional and esthetic aspects.

• Economic and Environmental Geology
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• v.32 no.4
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• pp.323-337
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• 1999

Late Cretaceous to early Tertiary volcanic rocks in the Kyongsang basin exhibit high-K calc-alkaline characteristics, and originated from the magmatism related genetically to subduction of Kula-Pacific plate. They represent HFSE depletion and LlLE enrichment characteristics as shown by magmas related to subduction. Early studies on the depth of magma generation has been estimated as 180-230 km based on K-h relation should be reevaluated, because the depth of peridotite partial melting with 0.4 wt. % water is 80-120 km at subduction zone, and subducting slab in premature arc can melted even lower than 70 km. Moreover the increase of potassium contents depends on either contamination of crustal material and fluids of subducting slab or low degree of partial melting. If the inclination of subduction zone is 30 degrees and the depth to the Benioff zone is 180-230 km, the calculated distance between the volcanic zone and trench axis would be 310-400 km. It is unlikely because the distance between the Kyongsang basin and trench during late Cretaceous to early Tertiary is closer than this value and not comparable with generally-accepted models in subduction zone magmatism. $K_{55}$ of the volcanics in the Kyongsang basin is 0.3-2.3 wt.% and the average indicate that the depth ranges between 80-170 km on the diagram of Marsh, Carmichael (1974). Fractionation from garnet lherzolite, assumed the depth of 180-230km, is not consistent with the REE patterns of the volcanoes in the Kyongsang basin. Futhermore, the range of depth suggested by many workers, who studied magmatism related to subduction, imply shallower than this depth. Crustal thickness calculated by the content of CaO and $Na_2O$ is about 30 km and about 35 km, respectively. Paleo-crustal thickness during late Cretaceous to early Tertiary times in the Kyongsang basin inferred about 30 km calculated by La/Sm versus LaJYb data, which is also supported by many previous studies.

• The Journal of the Petrological Society of Korea
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• v.13 no.4
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• pp.179-190
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• 2004

Precambrian metamorphic rocks of Yeongyang-Uljin area, which is located in the eastern part of Sobaegsan Massif, Korea, are composed of Pyeonghae, Giseong, Wonnam Formations and Hada leuco granite gneisses. These show a zonal distribution of WNW-ESE trend, and are intruded by Mesozoic igneous rocks and are unconformably overlain by Mesozoic sedimentary rocks. This study clarifies the deformation history of Precambrian metamorphic rocks after the formation of gneissosity or schistosity on the basis of the geometric and kinematic features and the forming sequence of multi-deformed rock structures, and suggests that the geological structures of this area experienced at least four phases of deformation i.e. ductile shear deformation, one deformation before that, at least two deformations after that. (1) The first phase of deformation formed regional foliations and WNW-trending isoclinal folds with subhorizontal axes and steep axial planes dipping to the north. (2) The second phase of deformation occurred by dextral ductile shear deformation of top-to-the east movement, forming stretching lineations of E-W trend, S-C mylonitic structure foliations, and Z-shaped asymmetric folds. (3) The third phase deformation formed I-W trending open- or kink-type recumbent folds with subhorizontal axes and gently dipping axial planes. (4) The fourth phase deformation took place under compression of NNW-SSE direction, forming ENE-WSW trending symmetric open upright folds and asymmetric conjugate kink folds with subhorizontal axes, and conjugate faults thrusting to the both NNW and SSE with drag folds related to it. These four phases of deformation are closely connected with the orientation of regional foliation in the Yeongyang-Uljin area. 1st deformation produced regional foliation striking WNW and steeply dipping to the north, 2nd deformation locally change the strike of regional foliation into N-S direction, and 3rd and 4th deformations locally change dip-angle and dip-direction of regional foliation.

• Economic and Environmental Geology
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• v.47 no.6
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• pp.571-588
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• 2014

It consists of the Precambrian Jirisan metamorphic complex and Sancheong anorthosite complex and the Mesozoic granitoids which intrude them in the Sancheong area, the Jirisan province of Yeongnam massif, Korea. The study area is located in the western part of the stock-type Sancheong anorthosite complex. We performed a detailed fieldwork on the Sancheong anorthosite (SA) and Fe-Ti ore body (FTO) which constitute the Sancheong anorthosite complex, and reinterpreted the origin of FTO foliation and the genetic relationship between them from the foliations, shear zones, occurrences of the SA and FTO. The new structural characteristics between them are as follows: the multilayer structures of FTO, the derived veins of straight, anastomosing uneven types and block structures related to the size reduction of SA, the gradual or irregular boundaries of SA blocks and FTO showing bulbous lobate margins and comb structures, the FTO foliation and linear arrangements of flow occurrence which is not ductile shear deformation, the discontinuous shear zone of SA, the orientation of FTO foliations parallel to the boundaries of SA blocks, the predominance of FTO foliations toward the boundaries of SA blocks and being proportional to the aspect ratio of plagioclase xenocrysts and SA xenoblocks, and the flow folding structures of FTO foliation. Such field evidences indicate that the SA is not fully congealed when the FTO is melt and the fracturing of partly congealed SA causes the derived veins of FTO and the size reduction of SA. Also the gradual or irregular boundaries of SA blocks and FTO result from the mutual reaction between the not fully congealed SA blocks and the FTO melt, and the FTO foliation is a magmatic foliation which was formed by the interaction between the FTO melt and the partly congealed SA blocks. Therefore, these suggest that the SA and FTO are not formed from the intrusion of different magmas in genesis and age but from a coeval and cogenetic magma through multiple fractionation. We predict that the FTO will show an very irregular occurrence injected along irregular fractures, not the regular occurrence like as the intrusive vein and dike. It can be applied to the designing of Fe-Ti mineral resource exploration in this area.

• Economic and Environmental Geology
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• v.57 no.1
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• pp.1-15
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• 2024

The Melanesian region in the western Pacific is dominated by complex plate tectonics, with the largest oceanic plateau, the OntongJava plateau, and a hotspot, the Caroline Islands. To better understand the complex geodynamics of the region, we estimate P- and S-velocity models and 𝛿 (V_P/V_S) model by using relative teleseismic travel times measured at seismometers on land and the seafloor. Our results show high-velocity anomalies in the subduction zones of the Melanesian region to a depth of about 400 km, which is thought to be subducting Solomon Sea, Bismarck, and Australian plates along plate boundaries. Along subduction zones, positive 𝛿 (V_P/V_S) anomalies are found, which may be caused by partial melting due to dehydration. A broad high-velocity anomaly is observed at 600 km depth below the Ontong-Java plateau, with a negative 𝛿 (V_P/V_S) anomaly. This is thought to be a viscous and dry remnant of the Pacific plate that subducted at 45-25 Ma, with a low volume of fluids due to dehydration for a long period in the mantle transition zone. Beneath the Caroline Islands, a strong low-velocity anomaly is obseved to a depth of 800 km and appears to be connected to the underside of the remnant Pacific plate in the mantle transition zone. This suggests that the mantle plume originating in the lower mantle has been redirected due to the interaction with the remnant Pacific plate and has reached its current location. The mantle plume also has a positive 𝛿 (V_P/V_S) anomaly, which is thought to be due to the influence of embedded fluids or partial melting. A high-velocity anomaly, interpreted as an effect of the thick lithosphere beneath the Ontong-Java plateau, is observed down to 300 km depth with a negative 𝛿 (V_P/V_S) anomaly, which likely indicate that little fluid remains in the melt residue accumulated in the lithosphere.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.199-205
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• 1998

Cullet Quality Control in auto glass bottle factory is the most important in recent days because of the increasing cost of materials in glass bottle. Since the composition of plate glass cullet is similar, the cullet quality using plate cullet in glass bottle factory is easily controlled. In addition to this, the price of plate glass cullet is so low that the cost reduction can be achieved. If the ratio of plate glass cullet and gush is over 25%, the liquidity of glass water become worse, which is caused by different compositions and viscosity of the components. As a results, Furnace bottom temperature becomes low and glass water becomes inhomogeneous. Thus production efficiency of glass bottle becomes low because of increasing devitrification in Dead Corner part in glass melting furnace. Three experimental methods – (1) increasing melting temperature, (2) using Booster, (3) using bubbler – were performed to increase the furnace bottom temperature and glass water homogeneity. The amounts of plate glass cullet was able to increase up to 90%, 70% and 60% without any devitrification using booster, bubbler and the method of glass melting temperature increase from $1480^{\circ}C$ to $1560^{\circ}C$ respectively. It is not possible to increase the glass melting temperature without the reduction of furnace operation time and the increase of fuel cost. The booster process has disadvantage of much electric energy consumption. Since the bubbler process uses physical convection of melting glass based on compression air, the homogeneity of molten glass is not so good as that of booster process but it can reduce the cost of glass bottle.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.283-298
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• 2022

In this study, we investigated the mineral geochemistry of the albite-spodumene pegmatite, associated exogreisen, and wall rock from the Boam Li deposit, Wangpiri, Uljin, Gyeongsangbuk-do, South Korea. The paragenesis of the Boam Li deposit consists of two stages; the magmatic and endogreisen stages. In the magmatic stage, pegmatite dikes mainly composed of spodumene, albite, quartz, and K-feldspar intruded into the Janggun limestone formation. In the following endogreisen stage, the secondary fine-grained albite along with muscovite, apatite, beryl, CGM(columbite group mineral), microlite, and cassiterite were precipitated and partly replaced the magmatic stage minerals. Exogreisen composed of tourmaline, quartz, and muscovite develops along the contact between the pegmatite dike and wall rock. The Cs contents of beryl and muscovite and Ta/(Nb+Ta) ratio of CGM are higher in the endogreisen stage than the magmatic stage, suggesting the involvement of the more evolved melts in the greisenization than in the magmatic stage. Florine-rich and Cl-poor apatite infer that the parental magma is likely derived from metasedimentary rock (S-type granite). P₂O₅ contents of albite in the endogreisen stage are below the detection limit of EDS while those of albite in the magmatic stage are 0.28 wt.% on average. The lower P₂O₅ contents of the former albite can be attributed to apatite and microlite precipitation during the endogreisen stage. Calcium introduced from the adjacent Janggun formation may have induced apatite crystallization. The interaction between the pegmatite and Janggun limestone is consistent with the gradual increase in Ca and other divalent cations and decrease in Al from the core to the rim of tourmaline in the exogreisen.

• Journal of Conservation Science
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• v.31 no.3
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• pp.309-318
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• 2015

The staff given with chair to Yi Gyeong-seok, senior official over 70 years old by King Hyeonjong of Joseon Dynasty is representative handcraft of Joseon Dynasty. Results of analysis on the metallic decoration show that the metallic ornament of the end part which is connected to the spade was made by rolling of iron plate and brass plating. The plated part is limited to the ornament of the end part connected to the spade and the plating was not applied to the spade. Brass including 20% zinc was used for the connecting part of guard while brass gilded iron was used for the spade. This suggests that the tone of the connecting part of the guard and the spade was not different for reason of visual harmonization. Potential applied plating method can be amalgam, dippping in molten brass, and brushing but the analysis result suggests that dipping in molten brass method is the most likely accepted method. The brass guard of knife was joined by tin-lead solder. Rivet used to fix the blade was made by pure iron as an optimum material which satisfies flexibility and strength.