Aircraft noise is something humans don't want. In this study, based on the Rotax 914 engine used in Korea, the propeller blade angle was changed by 1 degree and the engine RPM was changed to review the three-wing “G Company” propeller and the three-wing GSC wooden propeller. Select the best propeller pitch angle by measuring the change in propeller noise and thrust and the change in engine RPM due to the change in noise and thrust. We would like to present a propeller pitch angle suitable for the location of the airfield and the operation of the aircraft. Based on this, we would like to help resolve noise complaints around the airfiled.

In order to reduce environmental pollution, it is necessary to increase the recycling rate of waste. For this, the separation of recyclables is of utmost importance. The paper conducted a study to automatically discriminate containers by material for beverage containers among recyclables. We developed an algorithm that automatically recognizes containers by four materials: metal, glass, plastic, and paper by measuring the vibration signal generated when the beverage container collides with the bottom plate of the collection box. The amplitude distribution, time series information, and frequency information of the vibration signal were used to extract the characteristics indicating the characteristic difference of the vibration signal for each material, and a classifier was developed through machine learning using these characteristics.

This study is to investigate the effect of material for GPF on the PM reduction characteristics before the improvement of filter efficiency in GPF. The material of GPF was changed to ceramic and metal. The ceramic material was applied to SiC, and the metal materials were employed to STS 310s, STS 316s, and STS 410s. The number of honeycomb and wall thickness were set to 200CPSI, 0.3987mm, respectively. The inlet mass flow was fixed at 0.00695kg/s. The inlet air temperature was changed from 500K(0s∼350s) to 1000K(400s∼900s). It was found that the differences in loading amount according to the GPF materials were difficult to observe because the pore density and porosity were set to be the same to affect only the mechanical properties. STS 310s with the highest temperature value had the fastest regeneration time. However, as time goes on, SiC had the highest regeneration rate characteristics. The reason is that the high-temperature region in the GPF by the high-temperature exhaust gas was rapidly transferred toward the outlet due to the high thermal conductivity of SiC.

This study was to develop a piston rod made of SiC by applying a sintering treatment after press molding in order to replace the imported piston rod used in the past. As a result of evaluating the mechanical properties of the developed piston rod, the following conclusions were obtained. The surface roughness value of the piston rod made of silicon carbide was 0.950Ra, and the surface Vickers hardness value was 19.94GPa. As a result of XRD analysis of the surface of the prototype piston rod, the main crystalline phase was 6H-SiC, and the crystalline phases of 4H-SiC and α-SiC were existed. In addition, a trace amount of SiC was detected. As a result of SEM observation of the piston rod surface of the prototype, a number of large porosity were observed. As a result of measuring the surface hardness of the piston rod made of SiC, it showed 70% of the physical properties compared to imported products.

본 연구에서는 처리용기의 재질에 따른 광펄스의 살균 효과에 대해서 알아보았다. 처리용기의 재질에 따른 UV-C 의 광량은 대조구는 3.595W/m2이었으며, 두께 1 mm에서 석영은 3.358W/m2, 아크릴은 0.878W/m2, 그리고 유리는 0.060W/m2였으며, 빛의 투과율은 석영은 93.4%, 아크릴은 24.4%, 유리는 1.7%로 나타났다. 처리 용기 재질에 따른 살균 효과는 석영은 처리용기의 두께와 상관없이 대조구와 동일한 살균 효과를 보였으며, 아크릴은 1 mm 두께에서 60초 처리 후 1.1 log 사멸하였으며, 180초 처리 후에는 5.0 log의 사멸효과를 보였으며, 두께가 증가함에 따라 살균 효과가 현저히 감소하였다. 유리는 두께와 관계없이 살균 효과가 거의 없었다. 사멸패턴은 유리를 제외하고는 모두 bi-phasic의 형태를 보였으며, 사멸속도상수와 D 값은 대조 구는 k1값은 0.287 s−1이었으며, k2값은 0.072 s−1이었고, D1 은 8.02 s였으며, D2는 31.87 s였다. 1 mm의 두께에서 석영 은 k1은 0.284 s−1, k2는 0.069 s−1, 아크릴은 k1은 0.018 s−1, k2는 0.042 s−1이었고, 유리는 k는 0.004 s−1이었다. 두께 1 mm에서 D값은 석영은 D1=8.11 s, D2=33.87, 아크릴은 D1 =127.94 s, D2=54.83 s, 유리는 D=575.75 s로 나타났다.

When performing finite element analysis using materials with porosity the porosity shows different mechanical properties from the existing mechanical properties of the existing base materials. In this study the equivalent properties were calculated and verified by applying the representative volume element (RVE) method and assuming that the material with porosity is a 2D orthotropic material. In case of finite element analysis using porous material or composite material, it is inefficient to perform the analysis through material modeling. Based on the element volume and element stress values ​​derived using the finite element analysis program, the representative stress values ​​and elastic modulus matrix were calculated using Python. In addition, equivalent properties were derived using the calculated elastic modulus matrix. The pores were simulated by etching a thin plate specimen made of STS304 material in a certain pattern, and the elastic modulus and Poisson's ratio were measured through a UTM and compared with simulation results. It was confirmed that an error of 7.028% for elastic modulus and 10% for Poisson's ratio occurred, and through this, the validity of this simulation was verified.

Solar energy is being constantly studied since it can reduce green house gas by adapting cooling and heating system of domestic architecture as a clean energy source. This study confirmed the reliability of experimental apparatus with temperature measurement of each components by developing cooling and heating system which is combined with artificial solar thermal energy using halogen lamp and refrigerator, examined the heat transfer characteristics according to room internal temperature and lamp distance with the materials of emissive plate (acrylic, copper and stainless). As a result of it, We found that the room internal temperature 18℃ was finer than 21℃ and 24℃ in case of heat transfer rate according to each components. Also, copper in the material change of emissive plate was showed finer heat transfer effects than stainless because of high thermal absorptivity when lamp distance was short.

The demand for materials with porosity is steadily increasing and the need for porous materials is increasing in fields such as chemical engineering and energy storage. In order to minimize trial and error, verifying design validity through finite element method at the design stage has the advantage to verify design validity with low cost. However there are limitations in finite element analysis using porous materials. In this study calculating the equivalent mechanical properties reflecting the porosity was carried out, and the first step was the isotropic elasticity in plane stress condition. The equivalent elastic modulus and the equivalent Poisson's ratio were derived through simulation. Assuming that the voids exist in a two-dimensional symmetrical shape and a constant distribution, the unit cell was defined and the equivalent mechanical properties were calculated. The specimen with same condition were measured through a universal test machine (UTM), the elastic modulus and Poisson's ratio were measured. The similarity between the value obtained through the simulation and the value measured through the experiment was under 5%, so the validity of this simulation was verified. With this result, FEM with porous materials will be used for design.

본 연구는 2019년 경기도내 대형매장과 중소형매장 및 재리시장에서 유통 중인 스테인리스, 알루미늄, 철 등 금속제 주방기구 82건을 대상으로 중금속 등 11종(납, 카드뮴, 비소 등)의 오염도를 조사하여 금속제 주방기구의 위생관리를 위한 기초자료로 활용하고자 하였다. 금속제 주방기구의 용출시험결과, 금속의 용출빈도는 철>알루미늄>크롬, 니켈>아연>구리>납>비소>안티몬>주석> 카드뮴의 순으로 이었고 용출률은 7.3-93.9%이었다. 조사 대상 82건 중 알루미늄 주방기구 1건에서 니켈이 기준을 초과(결과 1.4 mg/L, 기준 0.1 mg/L 이하)한 것으로 나타났으며 그 밖에 기준이 설정되어 있지 않은 철에 코팅한 주방기구에서 니켈이 식품용 기구 및 용기·포장 공전 금속제 기준을 5배-193배 초과한 것으로 나타나 이에 대한 기준규격의 설정이 필요한 것으로 판단된다. 코팅하지 않은 금속제와 내부를 코팅한 주방기구 평균 용출량을 비교해보면, 알루미늄과 철은 코팅한 주방기구에서 낮게 나타났고 나머지 대부분의 중금속은 코팅한 주방기구에서 높은 수준으로 나타났다. 국산과 수입산으로 나누어 평균 용출량을 비교한 결과, 알루미늄과 철은 국산 및 수입산 모두 다른 중금속에 비해 높은 수준으로 나타났는데 알루미늄은 국산주방기구에서, 철은 수입산 주방기구에서 높게 나타났다. 주방기구의 코팅재질별로 평균 용출량을 비교한 결과, 불소수지 코팅에서는 알루미늄, 세라믹 코팅에서는 알루미늄, 철, 법랑코팅에서는 니켈, 알루미늄, 철, 구리, 기타(실리콘과 티타늄)코팅에서는 철의 용출량이 높게 나타났다.

Recently, the use of non-ferrous metals has been increasing to lighten the weight of automobiles and parts. In particular, demand for non-ferrous alloy materials such as aluminum alloys and magnesium alloys is increasing. The purpose of this study is to calculate the optimization process of friction stir welding by using different materials of AA5052 and AA6061. By analyzing the reaction value of tensile strength and elongation by full factorial design and Custom Design Methodology. In other words, we analyzed the optimization process according to rotation speed, feed rate, tool angle and tool shape. In conclusion, the optimal process for tensile strength was achieved by using a tool with a rotation speed of 900 RPM, feed rate of 270, tool angle of 2.5° and a triangle tool. and The rotation speed was 1003 RPM, the feed rate was 314.5, tool angle of 1° and a triangle tool, it was able to get the maximum value of elongation when using a tool of the form.

목적 : 안경 렌즈의 사용 기간에 따른 재질별 자외선과 가시광선의 투과율에 대해 알아보고자 하였다. 방법 : 5개사 총 118개의 사용자가 사용한 무색 단초점 안경 렌즈를 사용하였다. 사용 기간은 1년 미만, 1년 이상 2년 미만, 2년 이상 등 총 3개로 나누었다(1년 미만: 38개, 1년 이상 2년 미만: 46개, 2년 이상: 34개). 재질별 로는 중굴절(medium index, 1.55~1.56), 고굴절(high index, 1.60), 초고굴절(ultra high index, 1.67~1.74) 로 나누었다(중굴절: 32개, 고굴절: 66개, 초고굴절: 20개). 안경 렌즈의 광투과율은 Topcon사의 TM-1을 사용 하여 자외선(200~380 nm)과 가시광선(380~780 nm) 영역을 측정하였다. 결과 : UV, UVA, UVB 및 가시광선 투과율 측정값을 사용 기간별로 재질에 따라 비교한 결과 사용 기간이 1년 미만인 안경 렌즈의 재질에 따른 투과율 측정값은 유의한 차이가 없었다(p=0.189, p=0.197, p=0.081, p=0.073). 사용 기간이 1년 이상 2년 미만인 안경 렌즈의 재질에 따른 UV, UVA, 가시광선 투과율 측정값은 유의한 차이를 보이는 결과를 확인하였다(p=0.001, p=0.001, p=0.003). 사용 기간이 2년 이상인 안경 렌즈의 재질에 따른 투 과율 측정값은 유의한 차이가 없었다(p=0.673, p=0.674, p=0.982, p=0.138). 결론 : 본 연구 결과 사용한 안경 렌즈의 사용 기간에 따른 재질별 투과율에서 차이가 나타났다. 따라서 안경 렌즈의 재질과 사용 기간 선택에 도움이 될 것으로 사료된다.

국내에 유통되는 식품용 기구 및 용기·포장 중 4종류(유리제, 도자기제, 법랑 및 옹기류)의 재질, 총 198건을 수거하여 식품으로 이행 가능성이 있는 중금속(납, 카드뮴, 비소 및 안티몬)에 대하여 이행량을 ICP-MS 로 조사하였다. 식품유사용매는 4% 초산을 사용하여 25oC를 유지하면서 24시간 방치한 액을 시험용액으로 하였으며, 시험법 검증을 위하여 검량선, 검출한계, 정량한계, 회수율, 정밀성 및 측정불확도를 산출하였다. 이행량 조사 결과 유리제의 경우 납과 카드뮴은 각각 N.D.-752.21 μg/L, N.D.- 1.99 μg/L 이고, 도자기제는 납, 카드뮴 및 비소가 각각 N.D.-1,955.86 μg/L, N.D.-74.06 μg/L, N.D.-302.40 μg/L 이며, 법랑의 납, 카드뮴 및 안티몬은 각각 N.D.-4.48 μg/L, N.D.- 7.00 μg/L, N.D.-52.00 μg/L 이였다. 그리고 옹기류의 납, 카드뮴 및 비소는 각각 N.D.-13.68 μg/L, N.D.-0.04 μg/L, N.D.-6.71 μg/L 수준으로 확인 되었다. 이와 같은 결과를 근거로 유리제 등으로부터 식품으로 이행 가능한 중금속의 위해도는 총 섭취량대비 4.83% 이하로 비교적 안전한 것으로 판단된다. 또한, 본 연구결과는 국내에서 유통중인 유리제 등의 식품용 기구 및 용기·포장은 모두 국내의 기준·규격에 적합함을 확인하였다.

We study substrate support structures and materials to improve uptime and shorten preventive maintenance cycles for chemical vapor deposition equipment. In order to improve the rolling of the substrate support, the bushing device adopts a ball transfer method in which a large ball and a small ball are mixed. When the main transfer ball of the bushing part of the substrate support contacts the substrate support, the small ball also rotates simultaneously with the rotation of the main ball, minimizing the resistance that can be generated during the vertical movement of the substrate support. As a result of the improvement, the glass substrate breakage rate is reduced by more than 90 ~ 95 %, and the equipment preventive maintenance and board support replacement cycles are extended four times or more, from once a month to more than four months, and the equipment uptime is at least 15 % improved. This study proposes an optimization method for substrate support structure and material improvement of chemical vapor deposition equipment.

목적 : 본 연구는 렌즈의 재질과 축안정설계가 서로 다른 3종의 토릭소프트콘택트렌즈(이하 토릭SCL)에서 NIBUT (눈물막안정성 테스트)와 함께 축회전 정도 및 교정효과를 비교하고자 하였다. 방법 : 안과 질환이나 안과 수술이 없는 19(38 안)명의 대상자에게 서로 다른 3종의 Toric SCL를 착용하게 하였다. 3종의 렌즈로는 이중쐐기형 디자인렌즈(A렌즈), ASD 디자인렌즈(B렌즈), 프리즘밸러스트 디자인렌즈(C렌즈)를 사용하였다. 눈물막안정성을 확인하기 위해 대상자에게 3종의 렌즈를 착용시키고 Oculus Keratograph를 사용하여 NIBUT을 측정하였고, 교정효과는 안경교정 시력과 렌즈착용 시력을 비교 및 카메라가 장착된 슬릿램프를 이용하여 렌즈 착용상태의 회전축의 정도를 측정하였다. 모든 검사는 렌즈 착용 20분 후(단시간착용), 8시간 후(장시간)에 실시하였다. 결과 : 교정시력은 A렌즈가 착용초기에는 중간정도를 보였고, 장시간 착용 후에는 우수한 결과를 보였다. NIBUT의 결과 B렌즈는 착용초기 가장 우수하였으나(p<0.050), 장시간 착용 후에는 A렌즈와 비슷한 결과를 나타내었다 (p>0.050). 축안정성은 착용초기 A렌즈가 가장 우수하였다(p<0.050). 그러나, 장시간 후에는 B렌즈가 우수하였으나 통계적으로는 유의하지 않았다(p>0.050). 결론 : 하이드로로겔 소재인 A렌즈는 교정시력은 가장 우수하였으나, 눈물막안정성이 착용초기 보다 착용시간이 흐를수록 낮아지는 경향은 장시간 착용으로 인하여 렌즈의 함수율 유지가 어려워지는 것이 요인으로 사료되며, B렌즈가 렌즈착용 초기에 하이드로겔 및 실리콘하이드로겔 보다 눈물막안정성 및 축안정성이 양호한 것은 표면에 습윤 처리와 축안정화 디자인의 영향으로 생각된다. 또한, 실리콘하이드로겔 소재 프리즘밸러스트 디자인의 C렌즈의 경우 안정된 교정시력을 보여 주었으나 눈물막안정성 및 축안정성의 결과는 가장 불량하였다. 이는 실리콘하이드로 겔의 표면 처리 방법의 보완이 더욱 필요하다고 생각된다.

In this study, the experiments and analyses were carried out in order to investigate the fracture characteristics on the adhesive at the specimen bonded with aluminum and aluminum-foam. The same conditions were given for the experiments and analyses. The results are investigated by the graph of reaction force according to displacement. It was found that the experimental and the analytical data were very similar to each other. On the basis of the data, the reliability of the analysis data could be confirmed. The notches were produced at the distances of 40, 110, 150, and 190 mm from the front of the test specimen, and the maximum reaction force was compared accordingly. It was found that the highest reaction force was generated at the front end of the adhesive and the lowest reaction force was found at the middle of the adhesive interface. Finally, when the equivalent stress in the test specimen was examined, it was found that the highest stress was obtained at the distance of 110 mm. It can be deduced. As the notch formation point are similar to the point when stress is dispersed as the adhesive is peeled off, it is possible to infer the high stress compared to other test specimens.

In this study, we investigated the properties of adhesive materials with different lightweight materials such as CFRP and Al-foam. The specimens were tested and analyzed using DCB (Double Cantilever Beam) specimens. In order to secure the reliability of the finite element method, the test and analysis were carried out, and the reliability of the finite element method was secured by using the graph of reaction force to displacement based on the experiment and analysis. The study on the adhesive failure characteristics according to the position of notch hole proceeded. Notch holes were generated at the locations of 40, 110, 150 and 190 mm from the beginning of the specimen near the bonding interface, and the analysis conditions used were the same as those used for securing reliability. The obtained study results are compared with reaction force and equivalent stress. In the case of reaction force, the overall tendency is similar but the difference in maximum reaction force is found. It was found that higher reaction forces appeared at the beginning than at the end of the bonding interface. When the equivalent stresses in the specimens were examined, the value of CFRP was seen to be 30 times higher as much as that of Al-foam.