A basic metal deposition experiment for manufacturing aluminum parts was performed using WAAM (Wire arc additive manufacturing), and the cross-sectional shape of the laminate according to nine deposition conditions. The effect of heat input was analyzed for the bead shape according to the deposition conditions, and the deposition efficiency was calculated by analyzing the cross-sectional shape of thin-wall parts made of aluminum. The amount of heat input was used in the experiment from about 2.7 kJ/cm to 4.5 kJ/cm, and the closer the heat input was to 4.5kJ/cm, the higher the deposition efficiency was. The maximum lamination efficiency obtained through this study reached 76%.

Natural gas is the most realistic fuel among eco-friendly fuels. Natural gas production is limited, and in Korea, it is supplied and utilized in the form of liquefied natural gas (LNG). In the case of LNG, the vaporization point is 163 degrees below zero, so ordinary metal cannot be used due to its brittleness. The International Maritime Organization (IMO) defines metals that can be used in the IGC Code, and is used for storage containers, transportation containers, etc. based on the metals. Welding is essential in the manufacture of large structures such as LNG storage tanks. In this study, weldability studies related to cryogenic materials were conducted. In Part I of this study, high-manganese steel and part II were studied for two types of stainless steel (STS304L, STS316L), and in Part III, aluminum (AL5083). During laser welding, the shape of the Bead on Plate (BOP) was analyzed, and a total of nine cases were analyzed using laser power and welding speed as variables. It was confirmed that the penetration and the width of the welding width were linearly proportional to the amount of heat input. Based on this study, it is possible to conduct a follow-up study to find the optimal welding conditions for butt welding and fillet welding.

As the part of efforts to respond to the environmental pollution, the demand for clean energy is increasing. Natural gas is one of the most realistic alternatives, and interest in the storage and transportation containers to utilize the natural gas is growing. The production area of ​​natural gas is limited, and in Korea, it is imported in the form of liquefied natural gas. LNG is a cryogenic state with a vaporization point of -163°C, so the ordinary metal cannot be used due to its brittleness. The international maritime organization (IMO) defines the metals that can handle LNG in the IGC Code, and the research is ongoing. This study was a preliminary study to check the weldability of related metals and confirmed the shape of bead on plate (BOP) during the laser welding for each material. In part I, a study was conducted on the high manganese steel, and in part II, a study was conducted on the materials of STS304L and STS316L among the stainless steel. Based on this study, it can be used as an optimal welding condition for the butt and fillet welding.

As demand for eco-friendly energy increases, demand for natural gas and Liquefied natural gas (LNG) storage technologies continues to increase. LNG is a cryogenic environment with a temperature of -163°C, so ordinary metals cannot be used due to brittleness. Accordingly, IGC Code designates the cryogenic materials such as Invar, STS304L, Al5083-0, and High Manganese Steel. For fabricating those materials, research on welding possibility is the most important. Thus this study focused on the possibility of laser welding of the cryogenic materials. The weldability of High Manganese Steel was researched in this paper, the shape and the dimensions of the beads after bead on plate (BOP) welding were observed. The experiment was conducted on a total of 25 cases with laser power and welding speed of 5 cases each, and the width, height, and penetration of the beads were confirmed. It was confirmed that the paramenter of bead increased linearly with the laser power, and the paramenters of bead increased linearly with decreasing welding speed. Based on this study, high manganese steel can be applied in various industries by applying it to butt welding.

2 (Langmuir, Freundlich, Elovich, Temkin, and Dubinin-Radushkevich) and 3 (Sips and Redlich-Peterson)-parameter isotherm models were applied to evaluated for the applicability of adsorption of Cu(II) and/or phosphate isotherm using chitosan bead. Non-linear and linear isotherm adsorption were also compared on each parameter with coefficient of determination (R2). Among 2-parameter isotherms, non-linear Langmuir and Freundlich isotherm showed relatively higher R2 and appropriate maximum uptake (qm) than other isotherm equation although linear Dubinin-Radushkevich obtained highest R2. 3-parameter isotherm model demonstrated more reasonable and accuracy results than 2-parmeter isotherm in both non-linear and linear due to the addition of one parameter. The linearization for all of isotherm equation did not increase the applicability of adsorption models when error experiment data was included.

Batch adsorption tests were performed to evaluate the applicability of adsorption kinetic model by using hydrogel chitosan bead crosslinked with glutaraldehyde (HCB-G) for Cu(II) as cation and/or phosphate as anion. Pseudo first and second order model were applied to determine the sorption kinetic property and intraparticle and Boyd equation were used to predict the diffusion of Cu(II) and phosphate at pore and boundary-layer, respectively. According to the value of theoretical and experimental uptake of Cu(II) and phosphate, pseudo second order is more suitable. On comparison with the value of adsorption rate constant (k), phosphate kinetic was 2-4 times faster than that of Cu(II) at any experimental condition indicating the electrostatic interaction between NH3 + and phosphate is dominated at the presence of single component. However, when Cu(II) and phosphate simultaneously exist, the value of k for phosphate was sharply decreased and then the difference was not significant. Both diffusion models confirmed that the sorption rate was controlled by film mass transfer at the beginning time (t < 3 hr) and pore diffusion at next time section (t > 6 hr).

Cu(II) can cause health problem for human being and phosphate is a key pollutant induces eutrophication in rivers and ponds. To remove of Cu(II) and phosphate from solution, chitosan as adsorbent was chosen and used as a form of hydrogel bead. Due to the chemical instability of hydrogel chitosan bead (HCB), the crosslinked HCB by glutaraldehyde (GA) was prepared (HCB-G). HCB-G maintained the spherical bead type at 1% HCl without a loss of chitosan. A variety of batch experiment tests were carried out to determine the removal efficiency (%), maximum uptake (Q, mg/g), and reaction rate. In the single presence of Cu(II) or phosphate, the removal efficiency was obtained to 17 and 16%, respectively. However, the removal efficiency of Cu(II) and phosphate was increased to 50~55% at a mixed solution. The maximum uptake (Q) for Cu(II) and phosphate was enhanced from 11.3 to74.4 mg/g and from 3.34 to 36.6 mg/g, respectively. While the reaction rate of Cu(II) and phosphate was almost finished within 24 and 6 h at single solution, it was not changed for Cu(II) but was retarded for phosphate at mixed solution.

Aluminum nitride (AlN) powder specimens are treated by high-energy bead milling and then sintered at various temperatures. Depending on the solvent and milling time, the oxygen content in the AlN powder varies significantly. When isopropyl alcohol is used, the oxygen content increases with the milling time. In contrast, hexane is very effective at suppressing the oxygen content increase in the AlN powder, although severe particle sedimentation after the milling process is observed in the AlN slurry. With an increase in the milling time, the primary particle size remains nearly constant, but the particle agglomeration is reduced. After spark plasma sintering at 1400℃, the second crystalline phase changes to compounds containing more Al2O3 when the AlN raw material with an increased milling time is used. When the sintering temperature is decreased from 1750℃ to 1400℃, the DC resistivity increases by approximately two orders of magnitude, which implies that controlling the sintering temperature is a very effective way to improve the DC resistivity of AlN ceramics.

A Nanosized WO3 and CuO powder mixture is prepared using novel high-energy ball milling in a bead mill to obtain a W-Cu nanocomposite powder, and the effect of milling time on the structural characteristics of WO3-CuO powder mixtures is investigated. The results show that the ball-milled WO3-CuO powder mixture reaches at steady state after 10 h milling, characterized by the uniform and narrow particle size distribution with primary crystalline sizes below 50 nm, a specific surface area of 37 m2/g, and powder mean particle size (D50) of 0.57 μm. The WO3-CuO powder mixtures milled for 10 h are heat-treated at different temperatures in H2 atmosphere to produce W-Cu powder. The XRD results shows that both the WO3 and CuO phases can be reduced to W and Cu phases at temperatures over 700oC. The reduced W-Cu nanocomposite powder exhibits excellent sinterability, and the ultrafine W-Cu composite can be obtained by the Cu liquid phase sintering process.

MBR(membrane bioreactor)공정에서 막 오염이 진행되면 막간차압압력(TMP, transmembrane pressure)가 증가한다. 일반적으로는 막분리 공정에서 운전/휴지(F/R, Filtration/Relaxation) 방식을 적용하여 TMP의 증가를 억제하고 있다. 본 연구에서는 활성 슬러지 용액과 밀도가 유사한 구형 비드를 제작하여 MBR 하부에서 산기되는 공기와 함께 자연적으로 순환되도록 하였다. 그리고 이러한 장치의 운전에 따른 막간차압압력의 변화를 운전/휴지 방식 및 사인파형 연속 투과운전(SFCO, Sinusoidal Filtration Continuous Operation)방식을 이용하여 확인하고자 하였다.

We developed a Amylose magnetic beads (AMBs) based detection system for high efficient separation, concentration and detection of E. coli O157:H7 in real sample. AMBs were synthesized by amylosucrase from Deinococcus geothermalis (DgAS) with iron-oxide nanoparticle (NP). The design of amylose magnetic beads (AMBs) have studied by an enzymatic synthesis with optimized reaction condition such as substrate, sucrose, and iron-oxide NP. AMBs have specific feature. AMBs decorated with functional fusion protein, which consists in a maltose binding protein (MBP) and a streptococcal protein G (SPG). Amylose chains has maltose, thus MBP-SPG binds to the AMB. In addition, SPG specifically binds to the Fc part of antibody. That was used as a linker to immobilize antibody to the surface of AMBs. The resulting AMBs were efficiently separated and concentrated target bacteria, E. coli O157:H7. Concentrated sample is qualitatively analyzed by PCR. Our studies demonstrated that AMB-based PCR significantly reduced the limitation of detection as low as 10 1 CFU/mL, compared to that of conventional PCR. The principle of this system can be served as a high efficiency for detection method of any pathogenic bacteria. In addition, AMBs and MBP-SPG cross-linker protein developed in this study is expected to be applicable to the portable food based biological processing monitoring system.

유산균을 고농도로 배양하기 위하여 CaCO3를 각각 15%와 20%씩 첨가하여 직경이 서로 다른 CaCO3-alginate beads를 제조한 후, lactic acid에 대한 CaCO3-alginate beads의 반응 특성과 완충효과를 관찰하였으며, lactic acid에 대하여 완충작용이 있는 CaCO3-alginate beads를 이용하여 S. thermophilus ST-Body 1과 L. amylovorus DU-21을 고농도 배양하여 직접투입식 starter를 제조하였다. 본 연구에서 제조된 CaCO3-alginate beads는 CaCO3, alginate 함량 및 수분 함유율이 beads에 일정하게 고루 분포되어 있으며, 일정한 밀도를 갖는 입자임을 알 수 있었다. 또한 lactic acid에 대한 beads의 반응은 표면으로부터 일어나기 시작하여 내부로 진행됨을 확인하였으며, CaCO3-alginate beads 양의 증가는 결국 lactic acid와 반응할 수 있는 CaCO3 표면적의 증가를 가져오게 되며, 단위시간당 lactic acid와 반응하는 CaCO3의 상대적 증가를 가져오기 때문에 CaCO3-alginate beads 양의 증가는 lactic acid 용액 내부의 중화작용의 증가를 가져온다는 것을 확인하였다. 즉, CaCO3-alginate beads의 직경이 작을수록, 내부의 CaCO3 함량이 높을수록, 단위 부피당 넓은 표면적과 높은 중화작용을 가지므로 CaCO3-alginate beads를 pH neutralizer로 이용하여 유산균을 배양할 경우에는 CaCO3 함량이 높고 직경이 작은 CaCO3-alginate beads의 이용이 유산균 배양에 효과적임을 알 수 있었다. CaCO3-alginate beads를 이용한 유산균의 고농도 배양 시, pH와 생균수와의 상관성과 선형관계를 단순회귀분석법(simple regression)을 이용하여 최소자승추정량(least square estimator; LSE)을 구하여 검증한 결과, 각 X의 회귀계수의 값은 통계적으로 유의한 결과(p<0.05, p<0.01)를 보였다. 또한 R2 값은 S. thermophilus ST-Body 1와 L. amylovorus DU-21의 경우, CaCO3-alginate beads 무첨가구와 첨가구에서 각각 0.6310, 0.7505, 0.7452, 0.7609이였다. 이는 pH가 균 증식에 다소나마 영향을 주는 것을 나타낸다. 고농도로 배양된 S. thermophilus ST-Body 1과 L. amylovorus DU-21 균주를 이용하여 직접투입식 starter를 제조한 결과, 동결건조 보호제로 15% glycerol을 이용하였을 때 각각 91.96±1.35%와 89.09±4.49%의 생존율을 보였다. 본 연구에서 확립된 기법은 probiotics 조제나 정장제 조제방법에 있어서도 공히 적용 가능하므로 미생물 세포의 이용기법으로 그 생존율과 발효에 연관되는 기능보존과 수반되는 여러 분야에 적용한다는 면에서 산업적으로 중요하다고 사료된다.

There have been continuous efforts on automating welding processes. This automation process could he said to fall into two categories, weld seam tracking and weld quality evaluation. Recently, the attempts to achieve these two functions simultaneously arc on the increase. For the study presented in this paper, a vision sensor is made, a vision system is constructed and using this, the 3 dimensional geometry of the head is measured on-line. For the application as in welding, which is the characteristic of nonlinear process, a fuzzy controller is designed. And with this, an adaptive control system is proposed which acquires the bead height and the coordinates of the point on the bead along the horizontal fillet joint, performs seam tracking with those data, and also at the same time, controls the bead geometry to a uniform shape. A communication system, which enables the communication with the industrial robot, is designed to control the bead geometry and to track the weld seam. Experiments are made with varied offset angles from the pre-taught weld path, and they showed the adaptive system works favorable results.