• Journal of Korea Foundry Society
• /
• v.43 no.4
• /
• pp.187-193
• /
• 2023

Shell core making is an excellent process in terms of formability and desanding, but when the molten aluminum comes into con- tact with the shell core, gas generation by pyrolysis of the resin is inevitable. In addition, when the ventilation is inadequate, pores will remain inside the casting, which can directly lead to defects of the casting. While studies on the gas generation behavior of shell core making have been reported, the modeling of gas generation has not been extensively investigated. We will develop a gas evolution analysis method that considers the relationship between temperature and gas quantity for the core to be developed. We then use the developed method to analyze the flow and solidification behavior of metal molten metal during core mold design and low-pressure casting of cylinder head products, and predict the occurrence of casting defects to derive a casting method that min- imizes the occurrence of defects.

• Journal of Korea Foundry Society
• /
• v.32 no.4
• /
• pp.190-195
• /
• 2012

• Korean Journal of Food Science and Technology
• /
• v.32 no.3
• /
• pp.507-512
• /
• 2000

The headspace flavors of roasted tea, prepared with steamed and nonsteamed polygonatum roots, were absorbed in solid-phase microextraction(SPME) fiber coated with $65\;{\mu}m$ of carbowax/divinylbenzene(CW/DVB) and analysed by GC-MS. The absorption conditions of SPME fiber for equilibrated headspace were selected as $60^{\circ}C$ and 30 min. In a comparison for both samples roasted at $130^{\circ}C$ for 15 min, gas chromatograms showed a similar pattern in overall profiles between steamed and nonsteamed samples before roasting, but some differences were observed in peak characteristics. From 40 separated peaks, 25 compounds were identified with both GC-MS and retention time comparison. The pyrazines including 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, 2-acetyl-1-pyrroline, etc. were higher in their contents in nonsteamed-roasted sample than steamed-roasted one. In particular, steamed-roasted polygonatum showed higher contents of acetic acid(8.17%) and hexanoic acid(5.43%) than the corresponding compounds of nonsteamed-roasted one, 2.40% and 2.00%.

• Korean Journal of Food Science and Technology
• /
• v.34 no.4
• /
• pp.673-677
• /
• 2002

To develop a new traditional liquors using purple-fleshed sweet potato, the condition of alcohol fermentation was investigated by adding different concentrations $(5{\sim}75%)$ of cooked purple-fleshed sweet potato into mash and 10% nuruk, and fermenting for $5{\sim}15$ days. The maximum amount of ethanol (15.4%) was produced when 20% cooked purple-fleshed sweet potato and 10% nuruk were added into mash and fermented by S. cerevisiae at $25^{\circ}C$ for 15 days. The acceptability and physiological functionalities of the purple-fleshed sweet potato liquors were also investigated and compared. PSP-10 purple-fleshed sweet potato liquor prepared by adding 10% cooked purple-fleshed sweet potato into mash showed the best acceptability in the sensory evaluation test and color test $(pink{\sim}red)$; its fibrinolytic, electron-donating, and tyrosinase inhibitory activities were better than those of other purple-fleshed sweet potato liquors and wine.

• Journal of Biosystems Engineering
• /
• v.13 no.3
• /
• pp.11-19
• /
• 1988

분무량(噴霧量) 및 유량계수(流量係數)에 관(關)한 많은 연구(硏究)가 실험결과자료(實驗結果資料)에 기초하여 수행(遂行)되어졌다. 그러나 공시체(供試體)의 노즐의 특성(特性)에 따라서 유선(流線)의 특성(特性)이 다르므로 많은 실험결과(實驗結果) 및 해석(解析)이 서로 상치되는 점이 많다. 본(本) 연구(硏究)에서는 이론분석결과(理論分析結果)가 실험결과(實驗結果)와 다소 다르더라도 노즐 설계(設計)의 실제응용면(實際應用面)에서 필요(必要)한 노즐구조(構造)의 기본기능(基本機能)을 이론적(理論的)으로 분석(分析), 이해(理解)시키고저 한다. 이론분석(理論分析)의 결과(結果)는 다음과 같다. 공동면적(空洞面積)은 분구경(噴口徑), 와실경(渦室徑), 중자도구경(中子導溝徑) 및 중자도구각(中子導溝角)에 관계되고 있으며, 특히 중자도구각(中子導溝角)이 공동현상(空洞現象)에 큰 영향을 미친다. $$r_r{^6}-3r_o{^2}r_r{^4}+[3r_o{^4}+\frac{r_c{^4}r_o{^2}}{(r_c-r_g)^2\;tan^2{\theta}}]r_r{^2}-r_o{^6}=0$$ 반경방향(半徑方向) 힘의 요소(要素)로 인(因)한 유량계수(流量係數)($C_t$)는 산출식(算出式)은 아래와 같다. $$C_t=[1-(\frac{r_r}{r_o})^2]^{3/2}$$ 분무각(噴霧角)(${\alpha}$)은 공동반경(空洞半徑) 및 분구반경(噴口半徑)에 의(依)하여 변화(變化)된다. $${\alpha}=2\;tan^{-1}\(\frac{r^r}{\sqrt{r_o{^2}-r_r{^2}}}\)$$분무각(噴霧角)은 특히 와실유선각(渦室流線角)의 영향을 많이 받음을 시사하고 있다.

• Speech Sciences
• /
• v.10 no.4
• /
• pp.229-239
• /
• 2003

The purposes of this study are; to investigate the swallowing mechanism of stroke patients with different consistencies through the modified barium swallowing(MBS); and to establish preliminary data on the differences in swallowing durations. 4 different kinds of consistency-water, nectar, pudding, and crackers-were given to 6 stroke patients and their swallowing durations recorded through the fluoroscopy were measured in 1/100 second units. The results show that first swallowing time(FST), the oral preparatory duration(OPD), and the pharyngeal response duration(PRD) were delayed in swallowing thicker consistencies. However, water exhibited delayed oral and pharyngeal phase relative to its consistency and 50% of subjects showed oral loss of water. The relationship between consistencies and swallowing durations and the clinical issues on the stroke population were discussed.

• Journal of the Korean Society of Safety
• /
• v.11 no.3
• /
• pp.25-32
• /
• 1996

This study is a survey on the effect of working security and worksite environment connected to the worst case of noise and dust which was generated in the manufacturing workshop of machinery and easting. The noise intensity of the manufacturing process tends to increase up to the limited strength of 90db (A) or the higher during the last 4~5 years in 1990~1994. This result requires a significant improvement of worksite environment of unit workshop. The concentration of dust in the gouging process tends to increase to a significantly high level compared with other worksite, which also requires a local ventilation method to reduce the dust diffusion. Organic solvents used most frequently in the manufacturing process machinery were the aromatic hydrocarbons, but were gradually diversed in recent years.