• Laser Solutions
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• v.4 no.3
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• pp.22-29
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• 2001

A development of new surface clwaning technol ogies such as laser and aerosol in paeallel with the improvement of conventional wet mwthods becomes more essential in semiconductor industry due the confrontation of new challenges such as significant device shrink, environmental foralum inum do not work for copper as a new interconnection material, and more effective cleaning tools are required with decreasing the feature size less than 0.13 ㎛ as well as increasing the wafer size from 200 ㎜ to 300 ㎜. In this article, various cleaning techniques increasing laser cleaning are compared methodolgically hi order to understand their unique characteristics such as advantages and disadvantages according to the current clean ing issues. In particular, the current state of art of laser technique for semiconductors md prospects as a try cleaning method are described.

• The Korean Journal of Ceramics
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• v.4 no.4
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• pp.292-296
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• 1998

In wet powder processing of alumina, a number of organic molecules such as dispersant and binder are used to produce the flow behavior and properties requisite for shape forming. In this study, interparticle forces of alumina particles suspended in aqueous media were controlled by suspension pH, poly (methacrylic acid) (PMAA, used as dispersant) and poly (vinyl alcohol) (PVA, used as binder). The combined adsorption isotherms of the dispersant and binder additives on alumina were determined by total organic carbon analyzer, while the adsorption of dispersant was differentiated from binder in the mixed additive system by ultraviolet spectroscopy. The electrokinetic behavior of alumina suspensions were then correlated with the adsorption characteristics of dispersant and binder onto alumina particles. It was found that the isoelectric ($pH_{iep}$) of alumina shifted from pH 8.9${\pm}$0.1 to acidic pH as PMAA concentration increased, while PVA adsorption did not affect the $pH_{iep}$ but caused a decrease in the near surface potential.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1237-1241
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• 2003

In this paper, we report a novel RF-MEMS packaging technology with lightweight, small size, and short electric path length. To achieve this goal, we used the ultra thin silicon substrate as a packaging substrate. The via holes lot vortical feed-through were fabricated on the thin silicon wafer by wet chemical processing. Then, via holes were filled and micro-bumps were fabricated by electroplating. The packaged RF device has a reflection loss under 22 〔㏈〕 and a insertion loss of -0.04∼-0.08 〔㏈〕. These measurements show that we could package the RF device without loss and interference by using the vertical feed-through. Specially, with the ultra thin silicon wafer we can realize of a device package that has low-cost, lightweight and small size. Also, we can extend a 3-D packaging structure by stacking assembled thin packages.

• Carbon letters
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• v.7 no.1
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• pp.27-33
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• 2006

Carbon-ceramic composites were fabricated by using fly ash and PANOX fibers as reinforcement. Fly ash, because of its small size particles e.g. submicron to micron level can be effectively dispersed along with fibrous reinforcements. Phenolic resin was used as carbon precursor. Both dry as well as wet methods were used for forming composites. The resulting composites were characterized for their microstructure, thermal and mechanical properties. The microstructure and mechanical properties of composites are found to be dependent on type of the fly ash, fibrous reinforcements as well as processing parameters. The addition of fly ash improves hardness and the fibers, which get co-carbonized on heat treatment, increase the flexural strength of the carbon-ceramic composites. Composites with dual reinforcement exhibit about 30-40% higher strength as compared to the composites made with single reinforcement, either with fly ash as filler or with chopped fibers.

• Journal of the Korean Ceramic Society
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• v.26 no.2
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• pp.228-234
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• 1989

Pressureless-sintering of SiC with additions of yttria and alumina was studied. SiC could be densified to about 97% of its theoretical density at 185$0^{\circ}C$ which is about 20$0^{\circ}C$ below the normal sintering temperature of SiC with boron and carbon. Yttria and alumina formed intergranular liquid phases at the sintering temperature and promoted densification by the liquid phase sintering mechanism. The microstructure of sintered specimens was equiaxed and the liquid phase appeared to wet and dissolve SiC grains. The fracture toughness was measured by indentation method and found to be 5.3MPa.m1/2. Processing flaws near the surface of specimens appeared to be the major fracture origin during 3-point bending tests.

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.737-740
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• 1997

The influence of cyclic treatments with H2O2/DIW (1 : 10) and HF/DIW (1 : 100) on the roughness of silicon surface in the wet chemical processing was investigated by atomic force microscopy (AFM). During the step of the SC-1 cleaning, there is a large increase in roughness on the silicon surface which will result in the poor gate oxide breakdown properties. The roughness of the silicon wafer after the SC-1 cleaning step was reduced by cyclic treatments of hydrogen peroxide solution and hydrofluoric acid solution instead of HF-only cleaning. AFM images after each step clearly illustrated that the average roughness of silicon surface after three times treatments with H2O2 and HF solutions was reduced by 10 times compared with that after the SC-1 cleaning step.

• Transactions of Materials Processing
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• v.28 no.2
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• pp.77-82
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• 2019

Corrosion occurs well on surface of roll formed and Zn alloy subsequently electro-deposited on steel bolt under wet condition. In this study, variations in corrosion resistance were investigated through the measurement of polarization curves on steel bolts which were roll formed and subsequently coated with various types of coating methods. According to the measured polarization curve, Ni-P electroless deposits on roll formed steel increased the resistance to corrosion. The corrosion resistance of Zn alloy powder coated steel bolt was found to be better than that of Zn-Ni electro-deposited sample.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.5
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• pp.452-460
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• 2019

Exposure to heavy metals through the consumption of contaminated seafood poses a health risk to humans. In Korea, seafood imports are increasing with consumption, with the largest increase in imported seafood coming from Russia. Peter the Great Bay and the Razdolnaya River are both major fisheries and protected areas under the Northwest Pacific Action Plan located near Vladivostok, Russia. This study analyzed heavy metal [cadmium (Cd), lead (Pb), total mercury (tHg), and total (tAs), and inorganic (iAs) arsenic] concentrations in shellfish and crustaceans collected from these areas. Except for iAs, the major toxic heavy metal concentrations of the samples met the national standards (Cd, 0.024-0.982 and 0.003-0.379 mg/kg; Pb, 0.021-1.533 and 0.002 mg/kg; tHg, 0.006-0.015 and 0.036-0.097 mg/kg). The tAs concentrations of three samples exceeded the Russian standard (5 mg/kg, wet weight), whereas the iAs concentrations were extremely low (ND-0.033 mg/kg). Compared with the provisional tolerable weekly intake (PTWI) of the Ministry of Food and Drug Safety and Joint FAO/WHO Expert Committee on Food Additives, the percentages of PTWI of Cd, Pb, and tHg were 0.239%, 0.001-0.049%, and 0.013-0.302%, respectively. These findings reveal that there is no potential health risk by heavy metals through the consumption of Russian seafood obtained in the surveyed areas.

• Korean Journal of Food Science and Technology
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• v.37 no.4
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• pp.579-583
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• 2005

Effects of sangwhang mushroom (Phellinus linteus) powder and extract on quality of wet noodle were investigated by adding sangwhang mushroom powder at 2% (w/w: II) of wheat flour and extract at 17 (v/w: III) and 34% (v/w: IV) based on flour source, respectively. Significant decreases were found in L values of dough and noodle, while a and b values increased in proportion to addition of sangwhang mushroom. Addition of sangwhang mushroom decreased volume of cooked noodles, but increased turbidity of soup. Tensions of cooked noodle samples of II, III, IV, and control were 12.17, 17.61, 17.57, and 14.90g, respectively. Sensory properties, including color, flavor, taste, and texture, of noodles added with sangwhang mushroom extracts (III, IV) were significantly superior to control (I) and noodle added with powder (II). These results suggest addition of sangwhang mushroom extract is more suitable than powder for noodle processing.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.343-351
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• 2017

Sanitary evaluation of seawater and Pyropia sp. laver collected from the five major laver growing areas in Korea was performed four times over the course of a year. The seawater quality in four of these five areas was regarded as the clean area according to Korean criteria, but the seawater at one investigation site in Seoheon area was found to exceed the standard for fecal coliform. In the bacteriological safety analysis of laver (raw source), the percentages of samples not conforming to Chinese criteria at the five sites were 55.6% (Seocheon), 70.0% (Shinan), 81.8% [Jindo (Haenam)], 63.6% (Wando), and 28.6% [Goheung (Jangheung)]. Pathogenic bacteria were not detected in all laver samples. The food safety of laver (raw source) based on heavy metal concentration was confirmed using Korean criteria; the concentrations of heavy metals in laver samples collected from the major laver growing areas were 0.008-0.632 mg/kg wet weight (ww) lead, 0.024-0.137 mg/kg ww cadmium, 0.908-2.892 mg/kg ww total arsenic, and 0.003-0.013 mg/kg ww total mercury. Therefore, pollution source management and periodic monitoring of heavy metals may be required to improve the food safety of laver produced in these laver growing areas.