• Journal of Welding and Joining
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• 제28권3호
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• pp.79-85
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• 2010

Hardfacing is one of the frequently applying method to increase surface hardness in hot forging die. Recently, hardfacing receives great attention due to it's repair availability and low cost. In hot forging die, crack resistance and thermal shock resistance have been considered as major properties, However there are few studies for the assessment of these properties. So, it is necessary to establish the assessment method for crack resistance and thermal shock resistance in hardfacing for hot forging die. In this study, flux cored arc welding was applied to make hardfacing welds. Three point bending test was carried out to assess hardfacing weld's crack resistance, and high temperature bending test using salt bath was developed for thermal shock resistance. Consequently, it was possible to assess crack resistance and thermal shock resistance of hardfacing welds for hot forging die quantitatively.

• 한국표면공학회지
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• 제43권2호
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• pp.51-56
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• 2010

The zinc electroplating with respect to the chloride concentration was investigated by X-ray diffraction(XRD), scanning electron microscope (SEM), and cathodic polarization measurement. The cathodic overpotential during electroplating was first decreased and then increased with increase of chloride concentration in electrolyte. The decreased cathodic overpotential leads to preferred orientation of (002) plane, high current efficiency and satisfactory zinc deposits. The increased cathodic overpotential causes random orientation, low current efficiency and edge burning. The cathodic overpotential was affected by chloride concentration in electrolyte, not by the kind of chloride, such as NaCl and KCl. An optimized chloride concentration was 3 M for zinc electroplating. Also, it is considered that NaCl can be a alternation for KCl as a main salt of zinc electroplating bath.

• 한국응용과학기술학회지
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• 제19권2호
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• pp.117-122
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• 2002

A silicone softner (SS-5), a permanent press (PP) finish, was prepared by blending silicone oil KF-96 (as a lubricating component) and beef tallow hardened oil (as a softening component) which was synthesized from fatty polyamide salts. The prepared SS-5 and the PP finishing resin were applied to PP finishing cotton cloth and P/C gingham sample by one-bath method. The properties such as crease recovery, tear strength, and bending resistance were tested. The samples treated with SS-5 and PP finishing resin showed improved properties when comparing with the untreated ones, with the ones treated only with PP finishing resin, with ones treated with commercial PP finishing softners and PP finishing resin. The grades of fabric samples treated with 3% SS-5 were fifth grade in the bending resistance test.

• 한국염색가공학회지
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• 제8권1호
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• pp.15-25
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• 1996

Wool fabric and merino wool top were dyed with two dyes, C.I. Acid Red 13 and C.I. Direct Blue 1 in presence of hydrogen peroxide/glyoxal redox system at various conditions such as dyeing time, temperature and redox concentration. The pH of dye bath was 4.5 in buffer solution of $KH_{2}PO_{4}$ (0.1mol/1)/$Na_{2}HPO_{4}$ (0.1mol/1). Also dyeing of cotton fabric was carried out with C.I. Direct Blue 1 in absence or presence of redox system. The color depth(K/S) increased with redox concentration and dyeing temperature. The increases in dyeing rate and equilibrium dye exhaustion of Acid Acid 13 and Direct Blue 1 on wool fiber and fabric in the present of hydrogen peroxide/glyoxal have been caused by decreasing in pH value during dyeing process which due to the decomposition of hydrogen ion in glyoxal with the assistance of hydrogen peroxide. But the decreases in exhaustion of Direct Blue 1 on cotton may be attributed to repulsive interac ion between salt and salt.

• 한국환경생물학회:학술대회논문집
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• 한국환경생물학회 2003년도 학술대회
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• pp.86-91
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• 2003

In this study, in order to examine whether salt and heat shock stress would alter or not contraction and relaxation of isolated rat aorta. Under anesthesia with sodium pentobarbital(50 mg Kg$^{-1}$ i.p.), male Sprague Dawley rats weighing 300-330 g were subjected to 0, heat shock combined salt stress, where as the sham group was left at modified Krebs-bicarbonate solution. To measure contractile response of vascular ring preparation isolated from rat was determined in organ bath and was recorded on physiograph connected to isometric transducer. And the strip was checked for expression of heat shock protein(Hsps) by means of western blotting. The combination group of heat and 50 mM NaCl group increased vascular contractility, and the heat and 150 mM NaCl group decreased vascular contractility for 5 hours, and then recovered for 8 hours compared to that of control. Expressin of Hsp 70 of vascular muscle of rat aorta more increased by combination of heat and NaCl treatment than those of single treatment of heat or NaCl treatment, and vascular Hsp 70 showed a little decrease at 8 hours compared at 5 hours. These result indicate that mixed environmental stress either increased or decreased in vascular contractility by combination of heat and NaCl concentration.

• 한국의류학회지
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• 제26권2호
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• pp.349-354
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• 2002

In order to decolorize the reactive dye wastewater, we investigated the dye-adsorption ability of chitin, which was natural polymer obtained from shrimp shell. Chitin particle(less than 250 ${\mu}{\textrm}{m}$n) was prepared from shrimp shells in the processes of decalcification in aqueous hydrochloric acid solution and deproteination in aqueous sodium hydroxide solution. The particle size of chitin was controlled to less than 250 ${\mu}{\textrm}{m}$. Three tripes of the reactive dyes-C.I. Reactive Red 120, C.I. Reactive red 241 and C.I. Reactive Black 5-were used. Dye adsorption ability of chitin was investigated by dipping the particle in the dyebaths of concentration of 0.0l%, 0.03% and 0.05% for various periods of time(1,3,5, 10,20,40,80,160minutes). The influence of addition of salt(Na$_2$SO$_4$) and alkali to the dyebaths on dye-absorption was also investigated. We obtained the following results fur the dye-absolution ability of chitin in the dyebaths of three types of reactive dyes. 1) The amount of dye uptake by chitin was increased by addition of salt to the dyebaths. 2) As the concentration of alkali became higher than 3g/I, the amount of dye uptake by chitin was increased. Chitin showed good dye-adsorption ability, when the alkali concentration was high. 3) Chitin showed equal dye uptake in the three types of dyebaths when the dye concentration was 0.0l%. Over 90% of dyestuffs was adsorbed from the dyebaths in ten minutes. When the dye concentration was higher, better adsorption ability was showed in a dye bath of Reactive black 5 than in the others. When the dye concentration was 0.03%, 90% of Reactive red 120 and Reactive red 241 was adsorbed in 40 minutes and the same of Reactive black 5 in 10 minutes. When the dye concentration was 0.05%, 9()% of Reactive red 120 was adsorbed in 80 minutes, and Reactive black 5 in to minutes.

• 대한치과보철학회지
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• 제33권4호
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• pp.662-684
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• 1995

The purpose of this study was to evaluate the shear bond strength between various resin-bonded retainers and enamel according to the adhesive resins and retention types and observe the bond filure modes with scanning electron microscope(SEM). For this purpose, the followin eight sub-groups were tested in shear bond strength : 1) electrochemically etched group(Verabond) using Panavia EX and Superbond C&B 2) tin-plated group(PG-S) using Panavia EX and Superbond C&B 3) salt-treated group(Verabond) using Panavia EX and Superbond C&B 4) meshtreated group(Verabond) using Panavia EX and Superbond C&B. Thermocycling test was conducted on the condition of 15 second dwell time each in $5^{\circ}C$ and $55^{\circ}C$bath. Shear bond strength was measured by Instron Universal Testing Machine(medel 1125). The obtained results were as follows : 1. After thermocycling, the shear bond strengths of tin-plated group and electrochemically etched group were significantly greater than those of salt-treated group and mesh-treated group. And the shear bond strength of Panavia EX was greater than that of Superbond C&B with salt-treated group and tin-plated group(p<0.05). 2. Before thermocycling, electrochemically etched group using Superbond C&B produced the greatest shear bond strength(p<0.01). 3. The shear bond strength of electrochemically etched group using Superbond C&B was significantly decreased after thermocycling(p<0.01). 4. In observation of bond failure modes before thermocycling, Panavia EX highly exhibited enamel fracture. Tin-plated group using Superbond C&B adhesive failure between metal and resin and electrochemically etched group using Superbond C&B exhibited adhesive failure between enamel and rdsin. 5. In observation of failure modes after thermocycling, Panavia EX exhibited cohesive failure and Superbond C&B exhibited adhesive failure between resin and metal.

• 대한화학회지
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• 제10권1호
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• pp.32-42
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• 1966

$CaCl_2$, CaO 및 $WO_3$로 構成되는 熔融鹽을 黑鉛 陽極과 鐵 陰極으로 電解하여 순수한 金屬텅스텐을 얻는 方法에 관하여 실험하였다. 電氣分解에 적합한 熔融浴을 選定하기 위하여 $CaCl_2$-CaO系와 $CaCl_2-CaWO_4$系에 관한 二相 狀態圖를 작성하였으며 同時에 $CaCl_2$와 $WO_3$와의 高溫下에서의 化學反應을 검토하여 安定한 電解浴을 얻기 위해서는 一定量의 CaO가 添加되어야 할 것임을 알 수 있었다. 炭素陽極을 사용하여 $WO_3$를 W와 CO로 분해시킬 때의 分解電壓은 -0.1 volt이었으며 熱力學的 計算에 의한 것은 -0.3 volt이었다. 熔融鹽을 電氣分解한 結果 金屬텅스텐이 100%에 가까운 電流效率로 電極에 析出되나 이는 陽極에서 二次的으로 발생하는 CO가스에 의하여 쉽게 WC등으로 변화하므로 순수한 텅스텐을 얻기 위해서는 電解浴의 溫度를 $1100^{\circ}C$이상으로 유지하여야 된다는 것을 알게 되었다. 電解浴의 組成은 可及的 低融點과 $WO_3$의 分解, $CaCl_2$의 蒸發 등을 억제하기 위해서는 $CaCl_2$ 100分에 대하여 CaO와 $WO_3$가 각 10 乃至 20分이 適切하였으며 CaO와 $WO_3$의 몰比率은 1이상이 요구되었다. 陰極 電流密度를 1~5 $amp/cm^2$의 範圍에서 變化시켜도 電流效率에 큰 影響이 없었다.

• 한국염색가공학회지
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• 제16권4호
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• pp.19-25
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• 2004

Both poly(vinyl alcohol)$(PVA)-I_2$ and PVA-dye polarizing film were prepared using PVA with number-average degree of polymerization of 1,700, 2,300, 2,600. The optical property of used dye in this study closed to the that of iodine. The PVA-dye polarizing film was prepared through the dyeing process. In comparison of the result of the measurement of the heat and humidity resistance of two types polarizing films, it of PVA-dye polarizing film was higher than that of a conventional $PVA-I_2$polarizing film. The transmittance and the polarization efficiency of PVA-dye polarizing film was significantly influenced by dye concentration, dipping time, salt concentration, and temperature of dye bath. The PVA-dye polarizing film exhibited a high polarization efficiency of 99.3% and a good transmittance of 42.4%.

• 열처리공학회지
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• 제6권2호
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• pp.49-58
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• 1993

Isothermal transformation behavior during patenting and variations of microstructure and tensile strength of patented wires were investigated in Si-added high carbon steel. The TTT curves of the steels were made for two different austenitizing temperature. As the salt bath temperature was increased, the observed microstructures were bainite at $450^{\circ}C$, the mixture of bainite and pearlite at $500^{\circ}C$, and to pearlite at $600^{\circ}C$, The tensile strength of patented wire exhibited the highest value when the structure was pearlite. while the bainitic structure showed the lowest.