• Korean Journal of Heritage: History & Science
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• v.57 no.2
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• pp.6-25
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• 2024

This study concentrated on a report on the results of smelting experiments conducted eight times by the Jungwon National Research Institute of Cultural Heritage, put together the goals and results of the operation, and examined changes in the content of experiments and in the experimental results. First, changes related to operation, such as the ratio of raw materials to fuel and the presence or absence of additives, were reviewed depending on the operation goal. In addition, the results of metallurgical analysis of raw materials, formations, and byproducts were summarized and reviewed by comparing them with materials excavated from the ruins. The operation method varied up to the eighth smelting experiment in terms of iron ore roasting, additives, and raw material/fuel ratio. After reviewing the results again, pure iron with a low carbon content began to be confirmed through metallurgical analysis. As a result, it was confirmed that the charging ratio of raw materials and fuel plays an important role depending on the purpose of production. In addition, most of the products are gray cast iron, and it was deemed that this is due to changes in the internal structure of the pig iron while it was left in the furnace for a long time. The iron was an ingot that was in a molten state even though the carbon content did not reach 4.3%, where the process reaction takes place, and it was deemed to have been caused by excessive operating temperature. Based on the previously reviewed results and the structure and shape of the experimental furnace used in other ironmaking technology restoration experiments, this study finally attempted to restore the structure of an ancient iron smelting furnace, including the furnace's upper structure. By comprehensively referring to the remaining conditions of the excavated iron smelting furnace and the characteristics of the blow pipe, the form of the ancient iron smelting furnace was subdivided into six categories: furnace wall thickness, furnace height, blower height, blow pipe size, furnace inner wall shape, and top shape, and a restoration plan was proposed. To improve the problems of the restoration plan and the Jungwon National Research Institute of Cultural Heritage's experiments that have been conducted through continuous trial and error, an experiment that reflects changes in operating methods by lowering the furnace height and controlling the blowing volume is necessary.

• Journal of the Mineralogical Society of Korea
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• v.20 no.1 s.51
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• pp.47-60
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• 2007

While sedimentological researches on Western coastal tidal flats of Korea have been much pelformed previously, mineralogical and biogeochemical studies are beginning to be studied. The objectives of this study were to investigate mineralogical characteritics of the inter-tidal flat sediments and to explore phase transformation of iron(oxyhydr)oxides and biomineralization by metal-reducing bacteria enriched from the inter-tidal flat sediments from Muan, Jeollanam-do, Korea. Inter-tidal flat sediment samples were collected in Chungkye-myun and Haeje-myun, Muan-gun, Jeollanam-do. Particle size analyses were performed using the pipette method and sedimentation method. The separates including sand, silt and clay fractions were examined by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and X-ray diffiaction (XRD). After enriching the metal-.educing bacteria from the into,-tidal flat sediments, the bacteria were used to study phase transformation of the synthesized iron (oxyhydr)oxides and iron biomineralization using lactate or glucose as the electron donors and Fe(III)-containing iron oxides as the electron accepters. Mineralogical studies showed that the sediments of tidal flats in Chung]rye-myun and Haeje-myun consist of quartz, plagioclase, microcline, biotite, kaolinite and illite. Biogeochemical researches showed that the metal-reducing bacteria enriched from the inter-tidal flat sediments reduced reddish brown akaganeite and mineralized nanometer-sized black magnetite. The bacteria also reduced the reddish brown ferrihydrite into black amorphous phases and reduced the yellowish goethite into greenish with formation of nm-sized phases. These results indicate that microbial Fe(III) reduction may play one of important roles in iron and carbon biogeochemistry as well as iron biomineralization in subsurface environments.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.94-98
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• 2017

In the past few years, Sn-3.0Ag-0.5Cu (weight%) solder composition has been a representative material to electronic industries as a replacement of Pb-base solder alloy. Therefore, extensive studies on process and/or reliability related with the composition have been reported. However, recent rapid rise in Ag price has demanded solder compositions of low Ag content. In this study, Sn-3.0Ag-0.5Cu solder bar sample was fabricated by melting of Sn, Ag and Cu metal powders. Crystal structure and element concentration were analyzed by XRD, optical microscope, FE-SEM and EDS. The Sn-3.0Ag-0.5Cu solder sample was composed of ${\beta}$-Sn, ${\varepsilon}-Ag_3Sn$ and ${\eta}-Cu_6Sn_5$ phases.

• Analytical Science and Technology
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• v.23 no.1
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• pp.45-53
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• 2010

For the determination of chlorine in uranium compound, analytical methods by using a steam distillation and a pyrohydrolysis have been developed. The steam distillation apparatus was composed of steam generator, distilling flask and condenser etc. The samples were prepared with an aliquot of LiCl standard solution and a simulated spent nuclear fuel. A sample aliquot was mixed with a solution containing 0.2 M ferrous ammonium sulfate-0.5 M sulfamic acid 3 mL, phosphoric acid 6 mL and sulfuric acid 15 mL. The chloride was then distilled by steam at the temperature of $140^{\circ}C$ until a volume of $90{\pm}5\;mL$ is collected. The pyrohydrolysis equipment was composed of air introduction system, water supply, quartz reaction tube, combustion tube furnace, combustion boat and absorption vessel. The chloride was separated from powdered sample which is added with $U_3O_8$ accelerator, by pyrohydrolysis at the temperature of $950^{\circ}C$ for 1 hour in a quartz tube with a stream of air of 1 mL/min supplied from the water reservoir at $80^{\circ}C$. The chlorides collected in each absorption solution by two methods was diluted to 100 mL and measured with ion chromatography to determine the recovery yield. For the ion chromatographic determination of chlorine in molten salt retained in a metal ingot, the chlorine was separated by means of pyrohydrolysis after air and dry oxidation, and grinding for the sample.

• Journal of Animal Environmental Science
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• v.14 no.1
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• pp.61-68
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• 2008

The roof structural model of liquid manure storage tank was designed to improve a structural safety and an ability of resistance to corrosion by the bad environmental condition with high humidity and high gas concentration. Due to corrosion of a general steel, the 5 years used materials were reduced to one-third of a new material in the result of a bending strength test. Some structural materials were tested to evaluate a strength and an anti-corrosion, and stainless steel pipe (STS439), steel angle with zinc hot dipping, rectangular steel pipe covered with FRP (Fiberglass Reinforced Plastics) resin were selected finally. A stainless steel is more expansive about $3{\sim}5$ times than general structural steel. But its durability under heavy corrosive environment is expected twice as long as general steel. The roof models were designed as closed cone type for each of the three structural materials. In the result of a FEM (Finite Element Method) structural analysis for the developed models, the safe snow depth was higher 2.3 times than a general roof structure, when elements of equal section modulus were used.

• The Journal of the Petrological Society of Korea
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• v.5 no.1
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• pp.66-83
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• 1996

We report petrography, mineral chemistry, and major and trace element chemistry for rare tholeiites in Cheju island where alkalic rocks predominate. Available age data indicate that the tholeiitic magmatism was younger than 0.49Ma, possibly younger than 0.17 Ma. The tholeiites are generally fine-grained, porphyritic rock and show intergranular texture with lath-shaped plagioclase ($An_{61-46}$), orthopyroxene (bronzite) and olivine ($Fo_{78-67}$). Characteristically, two kinds of clinopyroxene (pigeonite and augite) occur only in groundmass. The tholeiites have normative quartz and show limited compositional variations ($SiO_2$=51.0-52.5 wt%; Mg＃=54-60). Major and transitional metal element variations of tholeiites are distinct from those of alkaline rocks in MgO diagram, suggestingthat the two rock types cannot be simply related to differentiation process from the same magma. The ratios among $K_2O$, Rb, Ba, Nb and La are similar for both tholeiites and alkali basalts, however the ratios between the elements (P, Y and Yb) having an affinity with garnet and the above elements are higher for tholeiites than for alkali basalts. These trace element ratios suggest that the tholeiites and alkali basalts were produced by different degrees of partial melting from a similar sources material (garnet lherzolite mantle).

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.40-40
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• 2010

산업현장에서는 파이프 또는 탱크류의 1GR용접에서 안정적인 이면비드를 가지는 루트패스 용접을 위해 2~3mm의 루트갭을 띄우고 용접봉 또는 필러와이어를 사용하는 TIG용접을 주로 한다. TIG용접은 고품질의 이면비드가 얻어지며, 용접인자의 제어가 쉽다는 장점이 있어 루트패스 용접에 많이 사용되고 있지만, 루트갭을 띄우면 이면비드는 잘 얻어지지만 용착금속량이 많아지게 되어 제작원가가 상승되고, 또한 소모성 와이어를 사용하는 GMAW에 비해 생산성이 낮다. 따라서, 안정적인 이면비드를 가지면서 생산성이 높은 1GR GMAW 루트패스 용접공정의 개발이 요구되지만, 이 경우도 루트갭이 2~3mm로 정해져 있으면 Fit-up공정에서 공수가 많이 필요하므로 근본적으로 루트갭이 없는 그루브에 대한 루트패스 용접이 더 바람직하다. 본 연구에서는 루트면 2.7mm를 가지는 U-그루브의 갭 없는 루트패스 용접에서 안정적인 이면비드가 형성되는 조건을 검토하기 위해 2.7t의 평판에 대하여 경사상진 각을 주고 기초 실험 후, U-그루브 맞대기 용접 실험을 진행하였다. 이 때, 경사상진 각은 용융금속이 중력으로 인해 아크 후방으로 밀리게 되고, 그로 인해 아크가 모재에 직접 닿게 되어 용입이 더 깊게되므로, 이면비드의 형성에 더 유리하다. 두께 2.7t의 연강 시편 2개를 갭 없는 I-그루브 맞대기 이음에서 Ǿ1.2 연강 솔리드 와이어를 사용하여 GMAW용접을 실시하였고, 용접전류, 용접속도, 경사상진 각, 위빙 폭, 위빙 주파수를 변경하여 각 조건에 대한 이면비드를 관찰하였다. 그 결과 경사상진 각 $25^{\circ}$, 전류 200A, 위빙폭 3mm, 위빙주파수 3Hz의 조건에서 안정적인 이면비드를 얻을 수 있었다. 또한, 현장에서 Fit-up중 발생할 수 있는 루트갭의 문제에 대하여 루트갭 1.2mm의 I-그루브 맞대기 용접에서 경사상진 각, 위빙 폭, 위빙 주파수는 갭 없이 실시한 실험에서 얻어진 가장 안정적인 결과를 사용하였고, 용접 전류, 용접 속도를 변경하여 이면비드를 관찰하였다, 그 결과 갭이 없을 때보다 약 80A 낮은 전류 조건인 120A에서 안정적인 이면비드를 얻을 수 있었다. 앞선 실험들을 기초로 하여 U-그루브 맞대기 용접을 실시 하였고, I-그루브 맞대기 용접에서 사용한 조건들과 유사한 용접 전류, 용접 속도에서 안정적인 이면비드를 얻을 수 있었다.

• Journal of Korea Foundry Society
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• v.32 no.1
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• pp.50-56
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• 2012

Fusion bonding of cast iron and Al alloy is an effective way to improve the properties such as low inertia, high efficiency and corrosion resistance in machinery parts. In case of fusion bonding, intermetallic compound layers are formed at the interface between cast iron and Al alloy interface. It is important to control the intermetallic compound layers for improving bonding strength. The formation behavior of intermetallic compound layer by heat treatment has been investigated. Heat treatment was performed at temperature from $600^{\circ}C$ to $800^{\circ}C$ with $100^{\circ}C$ interval for an hour to investigate the phase transformation during heat treatment. Heat treated specimens were analyzed by using FE-SEM, EPMA and EDS. The EPMA/WDS results revealed that various phases were formed at the interface, which exhibited 4 distinct intermetallic compound layers such as ${\tau}_6-Al_{4.5}FeSi$, ${\tau}_2-Al_3FeSi$, ${\tau}_{11}-Al_5Fe_2Si $and ${\eta}-Al_5Fe_2$. Also, fine precipitation of ${\tau}_1-Al_2Fe_3Si_3$ phase was formed between ${\tau}_{11}$ and ${\eta}$ layer. The phase fraction in intermetallic compound layer was changed by heat treatment temperature. At $600^{\circ}C$, intermetallic compound layer of ${\tau}_6$ phase was mainly formed with increasing heat treatment time. With increasing heat treatment temperature to $800^{\circ}C$, however, ${\tau}_2$ phase was mainly distributed in intermetallic compound layer. ${\tau}_1$ phase was remarkably decreased with increasing heat treatment time and temperature.

• Journal of Conservation Science
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• v.27 no.3
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• pp.301-312
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• 2011

Epoxy resin has superior durability and adhesive strength and proper physical strength so that it is used to diversity materials for multi-purposes. However epoxy resin is hardly removed after hardening specially once it is applied to artefacts, it is difficult to remove them under re-conservation. This paper is an experimental study on removing epoxy resin applied to iron objects using Nd:YAG laser cleaning system. Tests conducted in this study investigated how increasing laser energy and pulses would give effect on samples. The samples were prepared in a way that epoxy resin, itself pure and one which was mixed with pigment and they were applied to iron coupons and corroded iron coupons respectively. As a result of experiment, pure epoxy resin applied to corroded iron coupons was ablated at high laser energy but epoxy resin applied to iron coupons and mixing with pigment were not ablated but discolored and bubbled due to laser-induced heat generation. Results of FT-IR showed no component alteration of shifted resins and no residues on the surfaces ablated by laser irradiation. From SEM-EDS for removed surfaces, the debris from epoxy resin and melting iron was observed. Therefore, this study demonstrated the possibilities and limitations for laser cleaning to remove epoxy resin from iron objects.

• Fire Science and Engineering
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• v.31 no.2
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• pp.1-8
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• 2017

A sandwich panel is a composite material composed of a double-sided noncombustible material and insulation core which is used in the inner, outer walls, and roof structure of a building. Despite its excellent insulation performance, light weight and excellent constructability, a flame is brought into the inside of the panel through the joint between the panels, melting the core easily and causing casualties and property damage due to the rapid spread of flame. The current Building Law provides that the combustion performance of finishing materials for buildings should be determined using a fire test on a small amount of specimen and only a product that passes the stipulated performance standard should be used. This law also provides that in the case of finishing materials used for the outer walls of buildings, only materials that secured noncombustible or quasi-noncombustible performance should be used or flame spread prevention (FSP) should be installed. The purpose of this study was to confirm the difference between the dangers of horizontal and vertical fire spread by applying FSP, which is applied to finishing materials used for the outer walls of buildings limitedly to a sandwich panel building. Therefore, the combustion behavior and effects on the sandwich panel according to the application of FSP were measured through the construction to block the spread of flame between the panels using a full scale fire according to the test method specified in ISO 13784-1 and a metallic structure. The construction of FSP on the joint between the panels delayed the spread of flame inside the panels and the flash over time was also delayed, indicating that it could become an important factor for securing the fire safety of a building constructed using complex materials.