소형부품의 사각 컵 드로잉 성형 해석에 관한 실험적 연구

구태완,강범수 한국소성가공학회 2001 소성가공 : 한국소성가공학회지 Vol.10 No.6

Milli-structure components are classified as a component group whose size is between macro and micro scales, that is, about smaller than 20mm and larger than 1mm. The forming of these components has a typical phenomenon of bulk deformation with thin sheets because of the forming size. In this study, milli-structure rectangular cup drawing is analyzed and measured using the finite element method and experiments. Special containers or cases of cellular phone vibrator to save installation space are produced by rectangular-shaped drawing. A systematic approach is established for the design and the experiment of the forming processes for rectangular milli-structure cases. To verify the simulation results, the experimental investigations were also carried out on a real industrial product. The numerical analysis by FEM shows good agreement with the experimental results in view of the deformation shape of the product.

다양한 실규모 혐기소화조에서 유래된 프로피온산 분해 미생물 군집 구조 해석 및 생장역학 연구

구태완,이장우,Abu jannat⋅,황석환 한국폐기물자원순환학회 2016 한국폐기물자원순환학회 학술대회 Vol.2016 No.11

Anaerobic digestion is one of the most economical ways to treat organic wastes; the production of excessive sludge is limited; aeration is not required; operation cost is low; valuable energy resource (methane) is produced. However, propionate, an intermediate substance during the process, is known to inhibit biochemical process at high concentration; but it is difficult to be degraded biologically as its oxidation is thermodynamically unfavorable (△G>0). However, there are several microorganisms which could oxidize propionate fully by their syntrophic association. Therefore, in this research, the propionate enrichment culture was produced in large amount (~1L), and the main players which are responsible for utilizing propionate are identified. Furthermore, the kinetic parameter was obtained from this research. Seed came from two different full-scale anaerobic digesters which is located in Joongrang (JR) and Sincheon (SC). 16s rRNA gnee based metagenomics results indicated that Smithella propionica and Methanobacterium beijingense were the most dominant species in all seeds. The fact that bacterial family Syntrophomonadaceae and archaeal genus Methanosaeta were also found significantly in all seeds means that there might be symbiotic relationship among propionate oxidizing bacteria, butyrate oxidizing bacteria, hydrogenotrophic methanogens and acetotrophic methanogens in complete oxidation of propionate. Based on the first order kinetic which indicated propionate degrading rate, k (1/day) on JR and SC was represented 0.0243 and 0.0223, respectively. Also, based on Modified-Gompertz model, umax on JR and SC was represented as 0.024 and 0.016, respectively.

돈분뇨를 기질로 활용한 고부가 가치 상황버섯 균사체 배양조건 최적화 연구

구태완,이준엽,조경진,이장우,신승구,황석환 유기성자원학회 2015 유기물자원화 Vol.23 No.2

Newly, nutrients recovery by bioconversion in the swine waste which caused serious problems due to its high organic fraction and content of nutrients such as phosphorus and nitrogen is viewed as a considerable approach since it produces valuable product as well as recycling of resources. Consequently, it is necessary to find new methods to treat swine waste. One possible solution to this problem is to use this potential pollutant as a growth substrate for economically valuable products. The study for the fundamental improvement of bioconversion efficiency by finding optimum growth conditions using statistical models and biotechnology was performed. A novel approach to utilize swine waste by cultivating mycelia of the mushroom Phellinus linteus are described. A central composite face-centered design (CCF) for the experiments was used to develop empirical model providing a quantitative interpretation of the relationships among the three variables, which were substrate concentration, pH, and temperature. The maximal radial extension rate (2.78mm/d) of P.linteus was determined under the condition of 5.0 g COD/L, pH 5.0, and temperature 29.7℃. The results of this study suggest that swine waste could be utilized as a growth substrate for the cultivation of mushroom mycelia enhancing an efficiency of utilizing this by-product of the livestock industry.

농축산분야 미세먼지 활동도 자료 개선 연구

구태완,문수호,최두선 한국대기환경학회 2021 한국대기환경학회 학술대회논문집 Vol.2021 No.10

농업활동을 통해 1차적으로 발생할 수 있는 미세먼지로는 비산먼지가 있으며 주로 봄철 경운시기와 가을철 수확시기 및 농촌에서 농업잔재물을 소각하는 행위로 인한 미세먼지가 발생하고 있다. 더불어, 축산활동은 축사에서 발생하는 가축 사육두수에 의해 기인한다. 국내 2017년 기준 농업과 축산과 관련된 배출원(비산먼지) 중 미세먼지 배출량은 PM-10 20,533톤/년, PM-2.5 3,932톤/년이며 농업활동과 축산활동의 배출비율은 거의 50:50으로 나타났다. 현재 농업활동에 의한 미세먼지 배출계수와 활동도 자료는 미국 CARB (2007)를, 축산활동은 유럽 EEA(2006)를 그대로 적용하고 있듯이 아직까지 인벤토리와 활동도 자료가 개선되지 않았다. 따라서 본 연구는 국내 농업 및 축산활동 변화가 따라 기존 농업 및 축산활동 분야 활동자료인 시간적, 공간적 해상도의 개선안을 제시하고자 한다.

CMB 수용모델을 이용한 PM_2.5의 오염원 기여도 분석

구태완,홍민선,문수호,김호정,Koo, Tai-Wan,Hong, Min-Sun,Moon, Su-Ho,Kim, Ho-Jung 한국응용과학기술학회 2019 한국응용과학기술학회지 Vol.36 No.3

In this study, The Chemical Mass Balance (CMB) model was used to identify pollutant sources and their contributions to $PM_{2.5}$. The contribution rankings by emission source in A city were ash dust (30.1%) > biomass burning (21.9%) > secondary pollutants (21.1%) > mobile source (19.3%) > area sources (7.6%), and The emission sources increased from the contribution of the CMB model and the Clean Air Policy Support System (CAPSS) emissions were biomass burning and secondary pollutants, and The emission sources reduced were mobile source, ash dust, and area sources. 본 연구에서는 CMB(Chemical Mass Balance) 모델을 이용하여 $PM_{2.5}$에 대한 오염원 확인 및 오염원별 기여도를 분석하였다. A시의 배출원별 기여도 순위는 비산먼지(30.1%) > 생물성 연소(21.9%) > 2차 오염물질(21.1%) > 도로이동오염원(19.3%) > 면오염원(7.6%) 순이고, CMB 모델 기여도와 CAPSS(Clean Air Policy Support System) 배출자료 기여도 비교에서 증가한 배출원은 생물성 연소와 2차 오염물질이고, 감소한 배출원은 도로이동오염원, 비산먼지, 면오염원으로 분석되었다.

펜톤산화 공정에서 발생하는 슬러지의 재활용 방안 연구

구태완,조순행,최영수 대한환경공학회 1998 대한환경공학회 학술발표논문집 Vol.1998 No.12

입자요소를 이용한 미세 성형 부품의 유한요소 해석 및 실험

구태완,강범수,Ku, Tae-Wan,Kang, Beom-Soo 대한기계학회 2003 大韓機械學會論文集A Vol.27 No.1

The recent trend towards miniaturization causes an increased demand for parts with very small dimensions. Milli-structure components are classified as a component group whose size is between macro- and micro-scale. The manufacturing process of these components of thin sheet metal forming has a microscopic properties in addition to a typical phenomenon of bulk deformation because of the forming size. Also, the material properties and the deformation behavior change with miniaturization, which means that, a coarse grained materials show a higher resistance against deformation, when the grain size is in the range of the sheet thickness. In this study, a new numerical approach is proposed to simulate intergranular milli-structure in forming by the finite element method. The grain element and grain boundary element are introduced to simulate the milli-structure in the bending. The grain element is used to analyze the deformation of individual grain while the grain boundary element is for the investigation on the movement of the grain boundary. Also, the result of the finite element analysis is confirmed by a series of milli-sized forming experiments.

Numerical and experimental approach on energy dissipation in nano colloidal damper

구태완,S. B. Jeon,V. H. Bui,송우진,M. S. Park,강범수 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.10

Mechanical damping systems have been widely used to various mechanical structures and systems, and are mainly hydraulic and pneumatic devices nowadays. New damping system such as nano colloidal damper (NCD) is complementary to the hydraulic one, having a cylinder-piston-orifice structure. This study includes numerical and experimental investigation about energy dissipation of NCD by using porous silica particles. In numerical approach, the dissipated energy was obtained between compression and relaxation processes for porous silica particle in NCD according to the capillary tube theory. Furthermore, for colloidal damper, the hydraulic oil was replaced by a colloidal suspension that was consisted of a nano-porous matrix with controlled architecture and a lyophobic fluid. NCD test rig and the measuring technique of the hysteresis were described in this study. Performance of the energy dissipation between numerical and experimental results was investigated and compared. As a result, the proposed NCD was proved to efficiently dissipate the mechanical energy.

농업분야 비산먼지 활동도 자료의 시공간 해상도 개선 연구

구태완,신호용,우지윤,문수호,최두선,김윤관,전의찬 한국응용과학기술학회 2022 한국응용과학기술학회지 Vol.39 No.1

The emission factor and activity data of fugitive dust in the domestic agricultural field have been applied to the US inventory system without reflecting the domestic environmental conditions (wind speed, humidity, etc.) and agricultural characteristics. In this study, the temporal resolution was improved for each region by deriving a monthly distribution factor through the application of wind speed and dry season and the spatial resolution was improved for each region by subdivided into dong and ri from ci·gun·gu. Through this study, it is judged that it can be used as an important data for improving the emission and activity data of fugitive dust in the agricultural field that currently exist. 국내 농업 분야 비산먼지의 배출계수와 활동도 자료는 국내의 환경조건(풍속, 습도 등)과 농업의 특성을 반영하지 않고 미국의 인벤토리 체계를 그대로 적용해 왔다. 이 연구에서는, 활동 자료 중 하나인 시간 해상도는 풍속 및 건기일수 적용을 통해 월별 배분계수를 도출하여 지역별로 시간 해상도를 향상 시켰고, 공간 해상도는 시·군·구에서 동과 리로 세분화하여 지역별로 공간 해상도를 향상시켰다. 이 연구를 통해, 지금 존재하는 농업분야의 비산먼지의 배출량, 활동도 자료의 개선에 중요한 자료로 활용될 수 있을 것으로 판단된다.

A combined cold extrusion for a drive shaft: experimental assessment on dimensional compatibility

구태완 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.12

A combined cold extrusion process is experimentally visualized to manufacture a drive shaft. Due to the requirements of a face width of about 92.00 mm for the spur gear section and a groove depth of roughly 22.70 mm for the internal spline region, a preform is adopted to prevent excessive accumulation of plastic deformation. AISI 1035 medium carbon steel material is spheroidized and annealed to use as the initial billet workpiece. In order to verify the deformed configuration and the dimensional accuracy, both shoulder angles of (θ 1 , θ 2 ) are selected to be (30°, 30°) and (45°, 45°) on each extrusion die for the preform forging and the combined extrusion. Using the prepared tool components, experimental investigations on the dimensional relevancy of the cold forged drive shaft are performed. When the shoulder angle set of (30°, 30°) is applied, the required dimensions with respect to the face width and the groove depth are sufficiently satisfied, but unpredictable forging defects are observed. With the shoulder angles of (45°, 45°), the drive shaft is well deformed and fabricated without any cold forging defects. As a result, it is confirmed that the drive shaft can successfully be actualized with the dimensional precision satisfied by the combined cold extrusion.