• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.2
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• pp.89-95
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• 2000

Test fishing was carried out to examine the selectivity of the mesh size in trammel net for tonguefish (Cynoglossidae spp.) from May to August, 1999 and a total of 30 times of test fishing have been done in the coastal waters around Dolsando, Yosu, South Chunra province, Korea. A gill net and a trammel net which were composed of three different mesh sizes (70.5mm, 86.6mm and 101mm) were used for the experiment. The selectivity curve of mesh size was estimated by Kitahara's method for Robust tonguefish (Cynoglossus robustus). The results obtained are summarized as follows ; 1. Catching efficiency of the trammel net (70.5mm-sized-lint main net) was 39.0% and it was 2.5 times higher than 15.8% for the gill net. 2. The optimum l/m value of the trammel net was 3.51 and it was 0.13 higher than 3.38 for the gill net. 3. The selectivity of trammel net was similar to that of the gill net for low length-class. However, the selectivity of trammel net was not good compared with that of the gill net for high length-class. The 50% selectivity was 1.33 for the trammel net and 0.83 for the gill net. According to the experimental results, fishing efficiency of the trammel net was better than that of the gill net for tonguefish (Cynoglossidae spp.) and it was known that catch length for targeted species could be selected by controlling the mesh size.

• Journal of Biosystems Engineering
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• v.13 no.3
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• pp.1-10
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• 1988

Fraser, Dombrowski, Tanasawa 그리고 Momono 등(等)이 분구(噴口)에 대(對)한 중자도구(中子導溝) 단면적(斷面積)의 비(比)에 기초을 두고 있는 Nozzle Parameter가 클수록 유량계수(流量係數)는 증가(增加)한다고 보고(報告)하였다. 그러나 노즐의 구조(構造)는 중자도구(中子導溝) 및 와실(渦室)의 형상(形狀)에 따라서 특성(特性)을 가지고 있고 구조(構造)의 특성(特性)은 유량계수(流量係數), 분무각(噴霧角) 및 살포도(撒布度)에 지대한 영향을 미친다. 노즐구조(構造)에 관(關)한 이론분석(理論分析)의 결과(結果)는 다음과 같다. 중자도구변(中子導溝邊)(d), 중자(中子)두께(t) 및 중자도구각(中子導溝角)(${\theta}$) 등(等)의 관계(關係)가 와실유선각(渦室流線角)(${\theta}_c$)에 미치는 영향은 $$tan({\theta}_c)=\frac{t{\cdot}sin^2{\theta}}{d-t{\cdot}sin{\theta}{\cdot}(1-cos{\theta})}$$ 또한 와실유선각(渦室流線角)(${\theta}_c$)이 중자도구각(中子導溝角)(${\theta}$)과 일치(一致)하는 관계(關係)는 $\frac{d}{t}=sin{\theta}$이다. 와실유선각(渦室流線角)과 와실형상(渦室形狀)과의 관계(關係)는 $$tan({\theta}_c){\qeq_-}\frac{r_c-r_g}{L_c}$$ 이며 와실유선각(渦室流線角)은 와실유선회전반경(渦室流線回轉半徑)과 와실(渦室)길이의 비(比)에 의(依)하여 변화(變化)함을 시사(示唆)한다. Swirl core가 Swirl plate보다는 생산비(生産費)의 고려없이 압력손실(壓力損失) 및 마찰손실 면(面)에서 더욱 합리적(合理的)으로 고려(考慮)된다.

• Journal of Oriental Neuropsychiatry
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• v.3 no.1
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• pp.62-65
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• 1992

120 health korean and 43 korean with cancer (gastric, rectal, breast, aged 20 to C9 years in Yanbian district) were measured by atomic absorbtion spectrometer(Type WFX-II). The results obtained are as follows; in heath1 person hair, Zn $103.87{\pm}13.9$ppm, Cu $10.77{\pm}2.62$, Cr$0.288{\pm}0.121$ppm, Zn/Cu $10.77{\pm}3.24$. There is no significant difference betwen male and female, and korean and Han. Zn contents in hairs of patients with cancer significantly lower than that of health persons ; Cu and Cr contents are nearly same in both groups.

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

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.239-244
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• 2019

Traditional casting methods require long production lead time and high cost while not accommodating design changes easily. One of the technological alternatives to improve casting method to meet diversifying needs is Additive Manufacturing (AM). Among the 7 AM techniques, Powder Bed Fusion (PBF) is deemed most appropriate for casting applications. Currently, most AM machines are imported; therefore limiting the scope of available services and applications. This paper explores the domestic development of AM machines as well as the applications in casting. Each chapter describes development phases of PBF machines, applicable materials and parameter settings, while the last chapter illustrates a successful case of additive manufacturing industrial casting cores.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.245-250
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• 2019

In recent years, new technologies such as additive manufacturing have been applied to casting industry, paving new ways to achieve what have traditionally been impossible. In the global market, numerous successful cases of producing cores using additive manufacturing technology have been reported, and new techniques and markets are being developed under governments' support. In Korea, however; cases of applying additive manufacturing to casting are hard to come by, not to mention domestic AM machines and related technologies. Under these circumstances, introduction of additive manufacturing technologies and customized application to domestic casting industry are required. Each chapter of this paper explores topics ranging from the development of AM machine using binder jetting technology among various AM techniques through producing industrial cores to the on-site applications in the foundries.

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

• Journal of Korea Foundry Society
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• v.44 no.1
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• pp.19-23
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• 2024

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

• Journal of Korea Foundry Society
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• v.42 no.2
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• pp.136-144
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• 2022