• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.718-723
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• 2016

The use of the scroll compressor in the air conditioning of medium-sized vehicles has increased because of its low torque fluctuation, high energy efficiency and low noise. In addition, the main components of the compressor have been changed from steel to aluminum to reduce its weight, following studies on the constituent materials. The processing precision of the fixed scroll and orbiting involute scroll wrap of the scroll compressor must be below $10{\mu}m$. To ensure this, the surface roughness and contour tolerance are measured. To improve the hardness of the orbiting scrolls using aluminum subjected to anodizing treatment and as the base material, we used a sealing treatment and measured the resulting characteristics. The aluminum materials were made of an Al-Mg-Cu based alloy including small amounts of Ni, Fe, and Zn. The surface roughness was less than $3{\mu}m$ and the processing accuracy was within $10{\mu}m$. Also, the hardness of the nanodiamonds with CNTs used in the sealing treatment was more than 450. This was found to improve the hardness of the material by 50% or more compared to the water sealing treatment and there was little difference between the use of carbon nanotubes and nanodiamonds as sealing materials.

• Conservation Science in Museum
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• v.26
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• pp.119-142
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• 2021

The gilt-bronze-and-silver shoes, excavated from the Tomb of King Muryeong, revealed many defective parts, which constantly raised in-depth re-investigation and reporting. In that point, scientific treatment and analysis were conducted to investigate the manufacturing techniques applied. The conservation treatment was carried out with an emphasis on the restoration of the original form and joining parts. As a result, the upper part of the right shoe and some part of the back heel were joined, confirming the joining method and the number of rivet used for instep bonding. From the component analysis, it is presumed that the outer plate was gilded with mercury amalgam on pure copper, and pure silver was used for the inner plate. The main pattern of the gilt-bronze-and-silver shoes includes designs of phoenix, lotus, and six-petal flower, while the lotus pattern is high in terms of ratio. Thus, youngnaksa(twisted gilt-bronze thread), geumdongsa(gilt-bronze thread), wondujeong (rivet), and samyeonjeong(quadrangular cleats) were used for bonding each plate. Twisted gilt-bronze thread was used to join the inner and outer plates, while the center and rear of the inner plate were combined with only gilt-bronze threads. From the fact, it is presumed that the joining method was different whether the function was decoration or just bonding. Regarding the manufacturing process, traces of burnishing were confirmed on the outer surface of the gilt-bronze and silver shoes, but no burnishing traces were identified on the inner surface of the silver plate, which is likely to prove more importance put on the finishing of the outer plates rather than that of the inner.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.11-16
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• 2022

Metal-organic frameworks (MOFs) are porous materials with nano-sized pores. The degree of gas adsorption and pore size can be controlled according to types of metal ions and organic ligands. Many studies have been conducted on MOFs in the fields of gas storage and separation, and gas sensors. For rapid and quantitative gas adsorption/desorption analyses, it is necessary to form various MOF structures in uniform films on a sensor surface. In this review, some of representative direct methods for uniformly synthesizing MOFs such as MIL-53 (Al), ZIF-8, and Cu-BDC from anodized aluminum oxide, zinc oxide nanorods, and copper thin films, respectively on the surface of a microresonator are highlighted. In addition, the operation principle of quartz crystal microbalance and microcantilever, which are representative microresonators, and the interpretation of signals that change when gas is adsorbed to MOFs are covered. This is intended to enhance the understanding of gas adsorption/desorption analysis of MOFs using microresonators.

• Korean Chemical Engineering Research
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• v.62 no.2
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• pp.147-152
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• 2024

Most medical sensors are disposable products. In order to reduce inspection and diagnosis costs, it is more important to develop the inexpensive electrode materials. We fabricated the CuO NPs/PANI/E-PGE as an electrode material for disposable electrochemical sensors and applied it to a non-enzymatic glucose sensor. For surface activation of PGE, pretreatment was performed using chemical and electrochemical methods, respectively. Electrochemical properties according to the pretreatment method were analyzed through chronoamperometry (CA), cyclic voltammetry (CV) and electrochemical impedance (EIS). From these analytical results, the electrochemically pretreated PGE (E-PGE) was finally adopted. The non-enzymatic glucose sensor based on CuO NPs/PANI/E-PGE shows sensitivity of 239.18 mA/mM×cm² (in a linear range of 0.282~2.112 mM) and 36.99 mA/mM×cm² (3.75423~50 mM), detection limit of 17.6 μM and good selectivity. Based on the results of this study, it was confirmed that the modified PGE is a high-performance electrode material. Therefore, these electrodes can be applied to a variety of disposable sensors.

• Conservation Science in Museum
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• v.30
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• pp.23-46
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• 2023

The Jija Chongtong Gun, owned by Seokdang Museum of Dong-A University, is a tubedstyle heavy weapon of the battlefield in the mid-Joseon Dynasty and is the second largest firearm after Cheonja Chongtong. The original surface color of the Jija Chongtong Gun was obscured by foreign substances and therefore it was judged that its condition requires the conservation treatment. For stable conservation treatment, gamma ray and X-ray non-destructive transmission surveys was conducted to determine the internal structure and conservation condition. And the component analysis on the material components and surface contaminants of Jija Chongtong Gun was conducted by utilizing the p-XRF component analysis, SEM-EDS component analysis, and XRD analysis. As a result of the gamma-ray and X-ray non-destructive transmission investigation, a large amount of air bubbles was observed inside Jija Chongtong Gun, and the part that appeared to be a chaplet by visual observation was not identified. As a result of gamma-ray and p-XRF component analysis, it was confirmed that Jija Chongtong Gun was bronze made of copper (Cu), tin (Sn), and lead (Pb) alloy. As a result of surface analysis of foreign substances using SEM-EDS, it was confirmed that the main components of white foreign substances were calcium (Ca), sulfur (S), and titanium (Ti). Titanium was presumed to be titanium dioxide (TiO₂), the main component of white correction fluid. The red foreign substance was confirmed to contain barium (Ba) as its main ingredient, and was presumed to be barium sulfate (BaSO₄), an extender pigment in paint. White and red contaminants, mainly composed of titanium and barium, are presumed to have been deposited on the surface in recent years. The yellow foreign substances were confirmed to be aluminum (Al) and silicon (Si), and were presumed to have originated from soil components. As a result of SEM-EDS and XRD component analysis, the white foreign substance was confirmed to be gypsum (CaS). Based on the results of component analysis, surface impurities were removed, stabilization treatment, and strengthening treatment were performed. During the conservation process, unknown inscriptions Woo (右), Byeong (兵), Sang (上), and Yi (二) were discovered through a portable microscope and precise 3D scanning. In addition, the carving method, depth, and width of the inscription were measured. Woo Byeong Sang is located above Happo Fortress in Changwon, and Yi can be identified as the second hill.

• Korean Journal of Environmental Agriculture
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• v.13 no.1
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• pp.1-9
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• 1994

To investigate differences in Cu contents in paddy soils and rices, being affected by air pollutants from the Janghang Smelter, soil samples at the different directions and surface (0-15cm) and subsurface (15-30cm) were collected in 1982 and 1990, and rice plants at the soil corresponding sampling sites in 1990 were also at separately collected from the Janghang Smelter area. Soil samples were extracted with $4M-HNO_3$ and plant samples were digested with a mixture of $HNO_3$ and $HClO_4$ for analyzing Cu, Zn, Cd and Pb by atomic absorption spectrophotometry. The Cu contents in soils ranged from 5.1 to 391.0 mg $kg^{-1}$. The average content of Cu in 1990 was higher than that in 1982. The Cu content in soils nearer to the center of the smelter was higher than that farther from the center. The Cu content was highest at the east direction, and was in order of east > north-north east = north east > north. The variation of Cu levels in soil at east sites was more considerable than other directions. The Cu level in surface soils was higher than that in subsurface soils. The Cu contaminated area was within 5 km at east, and 3 km at north-north east and north east. A significant correlation was found between Cu content in surface soils of 1982 and that in surface and subsurface soils of 1990, and between Cu content in soils and soil properties such as organic matter(OM), available phosphate, available silicate, exchangeable $Ca^{++}$ and $Na^+$ in 1982. The Cu content in brown rice ranged from 0.4 to 3.6 mg $kg^{-1}$, and was the lowest in parts of rice plant, and Cu content in a part of plant was 13.75 times higher than that in brown rice. The Cu content of leaf sheath, stem and brown rice was correlated with the levels of Cd, Zn, Cu and Pb in soils. The Cu content in soil regardless of years and soil depths was correlated with Zn and Pb in soil in the area affected by waste gas.

• Journal of the Korean Electrochemical Society
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• v.18 no.1
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• pp.7-16
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• 2015

Effects of chemical composition ($Cu^{2+}$, $K_4P_2O_7$ and additive concentrations) of baths on properties of Cu thin films electrodeposited from pyrophosphate copper bath were investigated. Current efficiency was increased to be near 100% with increasing $Cu^{2+}$ concentrations from 0.02 to 0.3M. Decrease of current efficiency was observed in the range of 1.5~1.8M $K_4P_2O_7$ concentration, but current efficiency of about 100% was measured in the ranges of both 0.9~1.3M and 2.1~2.4M. The change of additive concentration did not influenced current efficiency. Residual stress of electrodeposited Cu thin films was measured to be about 20 MPa below 0.15 M $Cu^{2+}$ concentration and increased with the increase of it to 0.25 M. Maximum residual stress of 120MPa was observed at 0.25M $Cu^{2+}$ concentration. On the other hand, residual stress decreased from 80 to near 0 MPa as $K_4P_2O_7$ concentration varied from 0.9 to 2.4M and but The change of additive concentration did not affected on residual stress. $Cu^{2+}$ and $K_4P_2O_7$ concentrations significantly affect on surface morphology of electrodeposited Cu thin films, but additive concentration slightly affected. From XRD analysis, the microstructures of electrodeposited Cu thin film was affected from the changes of $Cu^{2+}$ and $K_4P_2O_7$ concentrations, but not from that of additive concentration. Strong preferred orientation of (111) peak was observed with increasing $Cu^{2+}$ and $K_4P_2O_7$ concentrations.

• Journal of radiological science and technology
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• v.31 no.3
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• pp.223-228
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• 2008

The most critical point in the medical use of radiation is to minimize the patient's entrance dose while maintaining the diagnostic function. Low-energy photons (long wave X-ray) among diagnostic X-rays are unnecessary because they are mostly absorbed and contribute the increase of patient's entrance dose. The most effective method to eliminate the low-energy photons is to use the filtering plate. The experiments were performed by observing the image quality. The skin entrance dose was 0.3 mmCu (copper) filter. A total of 80 images were prepared as two sets of 40 cuts. In the first set (of 40 cuts), 20 cuts were prepared for the non-filter set and another 20 cuts for the Cu filter of signal + noise image set. In the second set of 40 cuts, 20 cuts were prepared for the non-filter set and another 20 cuts for the Cu filter of non-signal image (noisy image) with random location of diameter 4 mm and 3 mm thickness of acryl disc for ROC signal at the chest phantom. P(S/s) and P(S/n) were calculated and the ROC curve was described in terms of sensitivity and specificity. Accuracy were evaluated after reading by five radiologists. The number of optically observable lesions was counted through ANSI chest phantom and contrast-detail phantom by recommendation of AAPM when non-filter or Cu filter was used, and the skin entrance dose was also measured for both conditions. As the result of the study, when the Cu filter was applied, favorable outcomes were observed on, the ROC Curve was located on the upper left area, sensitivity, accuracy and the number of CD phantom lesions were reasonable. Furthermore, if skin entrance dose was reduced, the use of additional filtration may be required to be considered in many other cases.

• Conservation Science in Museum
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• v.24
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• pp.1-16
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• 2020

This paper presents the process of re-conservation and the results of research on the production method of the Iron Sword with Ring Pommel with Three-Pointed Leaf Decoration, one of the excavation findings from Tomb No. 55 in the Dalseong Ancient Tomb Complex in Daegu. This iron sword is a double weapon with two large swords housed within a single sheath. Four smaller swords are attached to the surface of the sheath, two on the upper portion and the other two below. It is the only such two-in-one weapon excavated intact thus far from an ancient Korean tomb. The records show that it underwent conservation treatment twice in the past. In this study, it was subjected to conservation treatment again to replace the stiffener in some cracking areas, and its material, composition, and production method were analyzed by CT, XRF analysis, and stereoscopic microscopy. The sword is mainly made of copper, but the golden component contains both gold and mercury, which suggests that the copper was plated in gold using mercury amalgamation. The examination of the production methods indicates that it was intended more to demonstrate the authority of its owner rather than to serve any practical use. The two upper small swords on the sheath were made in the same manner as the main swords, and the two small lower swords were cut from a single metal sheet. The sheath was made by cutting two metal sheets. Supports were used to attach the two small swords to the upper portion of the sheath, while the lower portion of the sheath was slit to allow the other two small swords to be inserted into it. The ring pommels of the main swords have a three-pointed leaf decoration. As for the other designs, the handle of the main sword features a series of semicircles, the decorative bands on the sheath have waves in dots, and the fish tail of the sheath shows diagonal lines of dots.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.150-157
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• 1996

This study was conducted to observe the heavy matal contents of paddy soil and brown rice under long term fertilization with different soil amelioration materials. The contents of 0.1N HCl extractable Cu and Zn of surface soil increased in the plots of long term application with urea, ammonium sulfate, compost, lime and silicate fertilizers. The Cu and Zn contents of brown rice showed decreasing trends in same treatments of fertilizers and soil amelioration materials. But the contents of Cd and Pb in soil and brown rice were not affected in long term fertilization with soil amelioration materials.