• 한국주조공학회지
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• 제26권1호
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• pp.17-26
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• 2006

The substitution of cooling method from water quenching to air cooling after solution heat treatment was aimed for the development of a convenient and economical heat treatment process of duplex stainless steels without deterioration of mechanical and corrosion resistant properties for the industry. In order to achieve this goal, the mechanical properties and corrosion properties of a ASTM A890-4A duplex stainless steel were systematically investigated as functions of casting condition and cooling method after solution heat treatment. A 3-stepped sand mold and a permanent Y-block mold were used to check the effects of solidification structure and cooling rate after solution heat treatment. The microstructural characteristics such as the ferrite/austenite phase ratio and the precipitation behavior of ${\sigma}$ phase and carbides were investigated by combined analysis of OM and SEM-EDX with an aid of TTT diagram. Hardness and tension test were performed to evaluate the mechanical properties. Impact property at $-40^{\circ}C$ and corrosion resistance were also examined to check the possibility of the industrial application of this basic study. Throughout this investigation, air-cooling method was proved to effectively substitute for water-quenching process after the solution heat treatment, when the duplex stainless steel was sand mold cast with a thickness below 15 mm or permanent mold cast with a thickness below 20 mm.

• 한국표면공학회지
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• 제44권1호
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• pp.7-12
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• 2011

The effect of organic additives, polyethylene glycol (PEG), on the trivalent chromium electroplating was analysed in the view point of current efficiency, solution stability and metallurgical structure. It was measured that PEG-containing trivalent chromium solution had about 10% higher current efficiency than pure solution and controlled the micro-crack density of electrodeposits. PEG exhibited profound effect on the solution stability by reducing the consumption rate of formic acid which acts as a complexant to lower the activation energy required for electrochemical reduction of trivalent chromium ions. It was also revealed that the formation of chromium carbide layer was facilitated in the presence of polyethylene glycol, which meant easier electrochemical codeposition of chromium and carbon, not single chromium deposition. Trivalent chromium layer formed from PEG-containing solution was amorphous with local nano-crystalline particles, which were prominently developed on the entire surface after non-oxidative heat treatment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.386-387
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• 2006

This study is about the recycling technology of scrap a PCB(printed circuit board) produced in home appliances or automobile industry. And we develop the recycling technology of cooper (Cu)which is contained to leaching solution. In stead of electrolytic collecting in existing sulphuric atmosphere, we apply process using the ammonia solution which is used in economizing energy. So m the process of electrolyzing scrap a PCB through the leaching and separation, we examine the effect of the nickel contained to the solution and the cooper degree of purity which is changed according to current density.

• Journal of Positioning, Navigation, and Timing
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• 제10권2호
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• pp.103-111
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• 2021

A series of experiments have been carried out by using National Geographic Information Institute(NGII)'s Continuously Operating Reference Station (CORS) data with various strategies to analyze the impact of multi-GNSS measurements on baseline processing. The results of baseline processing were compared in terms of ambiguity fixing rate, precision, and hypothesis tests were conducted to confirm the statistical difference. The combination of multi-GNSS measurements has helped to improve ambiguity fixing rate, especially under harsh positioning environments. Combination of GPS, Galileo, BeiDou could get better precision than that of GPS, GLONASS, Galileo, and adding QZSS made the baseline solution's vertical component more precisely. The hypothesis tests have statistically confirmed that the inclusion of the multi-GNSS in the baseline processing enables not only to reduce field observation time length but also to enhance the solution's precision. However, it is of interest to notice that results of the baseline solution are dependent upon the software used. Hence, comprehensive studies should be performed shortly to derive the best practice to select the appropriate software.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2002년도 추계학술발표대회 논문개요집
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• pp.51-54
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• 2002

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.67-68
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• 2002

The properties and mechanism of silicon protuberance and groove processing by diamond tip sliding using atomic force microscope (AFM) in atmosphere were studied. To control the height of protuberance and the depth of groove, the processed height and depth depended on load and diamond tip radius were evaluated. Nanoprotuberances and grooves were fabricated on a silicon surface by approximately 100-nm-radius diamond tip sliding using an atomic force microscope in atmosphere. To clarify the mechanical and chemical properties of these parts processed, changes in the protuberance and groove profiles due to additional diamond tip sliding and potassium hydroxide (KOH) solution etching were evaluated. Processed protuberances were negligibly removed, and processed grooves were easily removed by additional diamond tip sliding. The KOH solution selectively etched the unprocessed silicon area. while the protuberances, grooves and flat surfaces processed by diamond tip sliding were negligibly etched. Three-dimensional nanofabrication is performed in this study by utilizing these mechanic-chemically processed parts as protective etching mask for KOH solution etching.

• 한국의류산업학회지
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• 제7권6호
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• pp.641-649
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• 2005

This study is to make pH 9 reduction by adding NaOH to 1, 3, 5, 7, 9, 11% solution of thioglycollic acid, cysteine, cysteamin, to add it on helically winded natural hair and colored hair and leave them for 20, 40, 60 minutes, to add $NaBrO_3$ oxidant for 15 minutes and to compare and analyze the wave form. This study showed the results of permanent using thioglycollic acid, cysteine, cysteamin. In the permanent wave form according to the kind of reductant, concentration, and processing time, there were a little difference between thioglycollic acid and cysteine. But cysteamine not only showed apparent difference but also formed strong and elastic wave. The permanent wave is affected by the diagonosis of hair, the choice of permanent solution and the processing time. Therefore the scientific diagonosis of hair is to be considered first of all. By choosing the kind of solution, the concentration and the processing time according to the results of hair diagonosis and wave form, we can prevent the lengthening and damage of hair.

• 정보처리학회지
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• 제9권1호
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• pp.82-86
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• 2002

• 한국식품저장유통학회지
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• 제15권6호
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• pp.816-823
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• 2008

숙성액 조성을 달리하여 양파장아찌를 제조하고 이화학적 품질 특성 변화를 조사하였다. 숙성액과 양파장아찌육의 당도(가용성 고형분), 염도, pH는 숙성기간이 경과함에 따라 간장배합비율이 높을수록 당도도 높게 나타났다. 양파장아찌육의 표면색도는 백색도의 경우 숙성기간 최종일까지 완만히 증가하였다. 적색도 및 황색도의 경우 모든 실험군과 대조군에서 감소하는 경향을 보였다. 양파장아찌의 견고성은 숙성기간 16일째에는 모든 실험군에서 급격히 감소하는 현상을 보였다. 씹힘성은 숙성기간 최종일에 모든 실험군에서 급격히 감소하였다. 관능검사의 경우 외관적인 색의 경우 간장 100%군이, 향은 간장 50%＋식초 50%인 실험군이, 맛은 간장 100%인 대조군이, 아삭거리는 정도는 간장 75%＋식초 25%인 실험군이, 전체적인 기호도는 간장 100%인 대조군이 높은 관능적 점수를 얻었다. 위의 결과를 종합해볼 때 양파장아찌숙성액 제조시 간장의 배합 비율을 높게하여 제조하는 것이 품질적으로 우수한 장아찌를 제조할 수 있을 것으로 판단된다.

• 자원리싸이클링
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• 제17권1호
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• pp.38-42
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• 2008

암모니아 용액중에서 바나듐(V)의 침출 시 바나듐의 용해와 후공정에서 $NH_4VO_3$로 침전 회수를 위한 조건에 관한 기초연구를 수행하였다. 침출공점에서 바나듐의 용해도를 높이기 위해서는 높은 온도가 필요하며 $(NH_4)_2CO_3$ 20g/L와 $NH_4OH$ 2.5M의 혼합 용액에서 반응온도가 $90^{\circ}C$일 때 용액 중 바나듐 농도가 16.8g/L이다. 한편 용해된 바나듐을 침전물 형태로 회수하기 위해서는 $25^{\circ}C$에서 $NH_4Cl$을 20g/L를 첨가하고 72시간 정치했을 때 용액에 잔류 바나듐의 농도를 0.0268g/L까지 낮출 수 있었으며 이 경우 바나듐의 회수율은 99.8%이었다.