• International Journal of Precision Engineering and Manufacturing
• /
• 제8권3호
• /
• pp.14-19
• /
• 2007

Rapid prototyping (RP) technology can fabricate any 3D physical model regardless of geometric complexity using the layered manufacturing (LM) process. Stereolithography (SL) is the best-known example of RP technology. In general, the surface quality of a raw SL-generated part is unsatisfactory for industrial purposes due to the step artefact created by the LM process. Despite of the increased number of applications for SL parts, this side effect limits their uses. In order to improve their surface quality, additional post-machining finishing, such as traditional grinding, is required, but post-machining is time consuming and can reduce the geometric accuracy of a part. Therefore, this study proposes a post-machining technology combining coating and grinding processes to improve the surface quality of SL parts. Paraffin wax and pulp are used as the coating and grinding materials. By grinding the coating wax only up to the boundary of the part, the surface smoothness can be improved without damaging the surface. Finally, moulding and casting experiments were performed to confirm the suitability of the SL parts finished using the proposed process with rapid tooling (RT) techniques.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.659-662
• /
• 2002

SL(Stereolithography) part is made by piling up thin layers which causes the stair stepping effect at the surface of SL parts. This effect brings about excessive surface roughness and requires additional post-process finishing such as abrasive techniques that are detrimental to part geometry and time consuming. Hence a wax coating and grinding post-process is proposed to improve the surface quality of SL part. The wax that has suitable properties for the proposed post-process is coated all over the part surface. By grinding the thin layer of coated on the SL part only, the surface roughness can be improved without any damage on the part. From the experimental results, This approach is considered to be very practical fur die casting with RT(Rapid Tooling) techniques.

• Preventive Nutrition and Food Science
• /
• 제17권4호
• /
• pp.269-273
• /
• 2012

Shinseoncho and kale were divided into stem [shinseoncho stems (SS) and kale stems (KS)] and leaf parts [shinseoncho leaves (SL) and kale leaves (KL)] and made into green vegetable juices for analyses of nutritional compositions and antioxidant activities. Higher values of total acidity were observed in SL (0.736%) and KL (0.841%) than in SS (0.417%) and KS (0.335%) (p<0.05). Neutral sugar content showed higher values in SS (21.740 mg/mL) and SL (18.657 mg/mL) when compared with KS (1.497 mg/mL) and KL (1.452 mg/mL) (p<0.05). Protein content showed the highest value in SL (7.610 mg/mL) (p<0.05), while SS (0.403 mg/mL) and KS (0.403 mg/mL) showed similar lower values. Total polyphenol contents of SL (423.139 ${\mu}g/mL$) was significantly higher value (p<0.05) than those of other samples, which occurred in the following order: SL>KL (218.494 ${\mu}g/mL$) KS (107.269 ${\mu}g/mL$)>SS (75.894 ${\mu}g/mL$). KL exerted the highest DPPH radical scavenging activity (84.834%) (p<0.05), which occurred in the following order: KL>SL (63.473%)>KS (52.894%)>SS (35.443%). ABTS radical scavenging activity showed that SL (66.088%) and KL (38.511%) had higher scavenging activities, whereas SS (7.695%) and KS (9.609%) demonstrated to be lower activities (p<0.05). In general, leaf parts had much higher antioxidant activities as well as total polyphenol contents than those of the stem parts. In conclusion, shinseoncho and kale, particularly their leaf parts, offer antioxidant properties in green vegetable juices and the consumption of them may be beneficial as a nutrition source and in health protection.

• 한국정밀공학회지
• /
• 제21권9호
• /
• pp.196-203
• /
• 2004

SL(Stereolithography) part is made by piling up thin layers which causes the stair stepping effect at the surface of SL parts. The effect brings about excessive surface roughness and cuts down the merits of using SL part. Hence, additional post-machining finishing such as traditional grinding is required. But the traditional post-machining is detrimental to part geometry and time consuming. In this study, therefore, a paraffin coating and grinding post-machining is newly proposed to improve the surface quality of SL fart. The paraffin which has suitable properties for the proposed post-machining is coated all over the part surface. By grinding the only over-coated paraffin based on boundary of the SL part surface, the surface roughness can be improved without any damage on the part. Also, it is verified that SL part finished by the proposed post-machining process can be applied for rapid tooling as pattern through manufacturing silicon rubber molding and casting test.

• 한국기계가공학회지
• /
• 제16권3호
• /
• pp.131-137
• /
• 2017

In this study, we evaluated the surface roughness of mold and injected parts manufactured by polycarbonate (PC) injection molding. The mold surface was polished to produce six differentiated roughnesses with 12 areas using stones (#800, #1200), sandpapers (#800, #1200), and diamond compounds (#8000, #14000). Injected parts were created using 20mm/s injection speed, 80 bar holding pressure for 5 seconds, and $70^{\circ}C$ cooling water. Injected parts surface roughness (Sa) was measured randomly in 10 of 30 using an interferometer (NewView8000, zygo, USA). In the same way, mold surface was measured randomly 10 times on 12 polished areas. Surface roughness of molds and injected parts were compared, and a regression equation to predict mold surface roughness was proposed for specific injection molding parameters.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.45-48
• /
• 2001

SL(Stereolithogrphy) part is made by piling up thin layers which causes the stair stepping effect at the surface of SL parts. This effect causes excessive surface roughness and requires additional postprocess finishing such as abrasive basting which is detrimental to part geometry and time consuming. Hence paraffin coating and grinding postprocess is proposed to raise the surface quality of SL part. The paraffin which has suitable properties for the proposed postprocess is coated all over the part surface. By grinding the thin layer of coated on the SL part only, the surface roughness can be improved without any damage on the part. From the experimental result, It is verified as very practical for die casting with silicon rubber mold.

• Journal of Ginseng Research
• /
• 제30권1호
• /
• pp.31-40
• /
• 2006

풍화 토양에서 셰일 지역이 높고 화강암 지역이 낮았으며, 셰일 지역이 화강암 및 천매암 지역에 비해 더욱 많은 원소에서 유의성이 높은 상관관계를 보였다. 인삼의 평균값에서 셰일 지역이 높고, 천매암 지역이 낮았다. 지역적 비교에서 셰일 지역이 높았고, 3년생이 많은 원소에서 유의성이 높은 상관관계를 보였는데, 이는 인삼이 연생이 증가함에 따라 토양으로 부터 필요한 만큼의 원소를 흡수하고 있음을 암시한다 인삼의 연생 차이별 비의 비교에처 화강암과 천매암 지역은 2년생이, 셰일은 3년생이 높았다. 지상부에 대한 연생 차이별 비교 시 화강암 지역은 2년생이, 천매암 지역은 1년생이 높았다. 동일 연생 비교 시 셰일지역이 높고 천매암 지역이 낮았다. 대부분 원소 쌍에서 정의 상관관계를 보였고, 3년생이 높은 유의성의 상관관계를 보였다. 뿌리에 대한 연생 차이별 비교 시 화강암 지역은 2년생이, 천매암 및 셰일 지역은 3년생이 높았다. 동일 연생 비교에서 셰일 지역이 높고 천매암 지역이 낮았다. 지상부에 비해 높은 유의성의 상관관계를 보였는데 이는 뿌리 부분에거 흡수되는 원소들 사이에서 좋은 상관성이 있음을 암시한다. 지상부와 뿌리 부분의 비교에서 지상부가 높은 원소 함량을 보이고,이 경향은 천매암 지역의 2년생에서 가장 높았다. 지상, 지하부의 비에서 LREE가 HREE 보다 커서 지상, 지하부의 차이가 LREE에서 컸음을 암시하고, 2년생이 대체로 높아 2년생의 지상부가 뿌리에 비해 높음을 암시한다. 토양과 인삼 함량과의 비교에서 거의 대부분 원소가 인삼에 비해 토양에서 높았고, 토양/지상부 비보다 토양/지하부비가 컸다. HREE의 비율 차이가 커서 HREE가 더욱 토양의 조성과 차이를 보임을 암시한다. 2년에서 3년생으로 갈수록 비율 차이가 커져 토양과 인삼의 조성차이가 나이가 들어감에 따라 커짐을 암시한다. 전체적인 결과들은 셰일 지역의 인삼이 제일 토양의 조성에 가까웠고 천매암 지역에서 가장 차이가 컸음을 암시한다.

• 한국정밀공학회지
• /
• 제27권3호
• /
• pp.135-141
• /
• 2010

Researchers continue to explore possibilities for expanding additive manufacturing (AM) technologies into direct product manufacturing. One limitation is in the materials available for use in AM that can meet the needs of end-use applications. Stereolithography (SL) is an AM technology well known for its precision and high quality surface finish capabilities. SL builds parts by selectively crosslinking or solidifying photo-curable liquid resins, and the resin industry has been continuously developing new resins with improved performance characteristics. This paper introduces a unique SL machine that can fabricate parts out of multiple SL materials. The technology is based on using multiple vats positioned on a rotating vat carousel that contain different photo-curable materials. To change the material during the process, the build platform is raised out of the current vat, a new vat with a different material is rotated under the platform, and the platform is submerged into the new vat so that the new material can be used. This paper introduces a new vat exchange mechanism, cleaning process, recoating process, resin leveling mechanism and process planning technologies for the implementation of multiple material SL. An overview of the system framework is provided and the system integration and control software is described. In addition, several multiple material test parts are designed, fabricated, and described.

• 한국기계가공학회지
• /
• 제13권2호
• /
• pp.15-20
• /
• 2014

The stereolithography(SL) process is a type of fabrication technology which relies on photopolymerization. It has a relatively simple fabrication process and a resolution of several tens of ${\mu}m$. Recently, SL technology has been applied to various areas, such as bioengineering and MEMS devices, due to the development of advanced materials. This technologycan be divided intothe scanning(SSL) and projection (PSL) types. In this paper, in stereolithography, parts are fabricated by curing photopolymeric resins with light. The application of stereolithography can now include fabricated parts. This process, called stereolithography, can fabricate parts by taking into account theirdegrees of geometry complexity. In particular, UV-LED stereolithography can perform quite rapid fabrication in which specific cross-sections are cured upon exposure to light.

• 한국정밀공학회지
• /
• 제27권6호
• /
• pp.98-104
• /
• 2010

Rapid Prototypes with internally colored objects are convenient by visualizing. A rapid prototyping method has been developed to fabricate mono-colored or multi-colored objects. In this work, a new process was proposed that can fabricate internally visible colored 3D objects in stereolithography parts. The process consists of projection stereolithography process using transparent photocurable resin for outer shapes and molten ink deposition process using molten solid ink for internal shapes. In molten ink deposition process, molten solid ink could be deposited uniformly in a designed pattern. To make molten solid ink uniform over a designed region, parametric study through a patterning solid ink was performed. By laminating resin and solid ink in sequence, the process can make colored 3D objects in StereoLithography(SL) parts. The practicality and effectiveness of the proposed process were verified through fabrication of colored basic 3D objects in SL parts.