• 제목/요약/키워드: SHELL

검색결과 5,868건 처리시간 0.032초

알킬 아크릴레이트계의 다중 Core-shell 복합입자의 제조 (Manufacture of Alkyl Acrylate Multi Core-shell Composite Particle)

  • 조대훈;최성일;고현미;설수덕
    • 접착 및 계면
    • /
    • 제12권1호
    • /
    • pp.16-25
    • /
    • 2011
  • Core 입자로 methyl methacrylate (MMA), n-butyl methacrylate (BMA)를 하고 shell 입자로 MMA, BMA, stylene (St), 2-hydroxylethylmethacrylate (2-HEMA), acrylic acid (AA)를 각각 사용하여 개시제 aommonium persulfate (APS), 유화제로 sodium dodecyl benzene sulfonate (SDBS)의 농도(0.01~0.03 wt%), 단량체의 종류와 조성을 변화시켜 수용성 유화중합으로 다중 core-shell 복합입자를 제조하여 전화율, 입자경 및 입도 분포, 평균 분자량, 분자구조, 유리전이온도, 입자의 형태 및 인장강도와 신율을 각각 측정하여 다음과 같은 결론을 얻었다. SDBS 농도 0.02 wt%에서 MMA core-(BMA/St/AA) shell 복합인자가 전화율이 98%로 우수하였고, 입자 직경은 SDBS 농도 0.03 wt%에서 BMA core-(MMA/St/AA) shell의 복합입자가 $0.47{\mu}m$로 높게 나왔다. 유리전이온도 측정은 단일 core-shell 복합입자의 2군데에 비하여 다중 core-shell 복합입자는 3군데가 존재하여 shell단량체 내의 단량체의 종류와 조성에 따라 유리전이온도 조절도 가능하고 동시에 접착력이 향상된 접착소재로서 부직포 섬유 결속제로 사용될 수 있었다.

경제성 분석에 의한 싱글쉘 터널의 국내 적용성 검토 연구 (Applicability of the single shell tunnel in Korea from the economic evaluation)

  • 김학준;신휴성
    • 한국터널지하공간학회 논문집
    • /
    • 제10권2호
    • /
    • pp.167-175
    • /
    • 2008
  • 터널공사비에 대한 국내외의 사례 조사 결과 싱글쉘 터널은 기존의 콘크리트 라이닝을 설치하는 이중쉘 터널에 비하여 공사비가 저렴하였다. 그러나 암반 상태가 불량해 질수록 싱글쉘 터널의 경제성은 급격히 저하되었다. 따라서 싱글쉘 공법은 암반상태가 양호한 지반에 적용해야 한다. 국내의 경우 일반적으로 여러 암반 등급이 다양하게 나타나므로 양호한 암반과 불량한 암반의 비율을 고려하여 싱글쉘 공법의 적용 여부를 판단해야 한다. 싱글쉘에 이용되는 숏크리트 및 록볼트는 영구지보재로서 고품질이어야 하므로 지보재료의 저렴한 공급여부에 따라서 싱글쉘 공법의 적용 대상 암반이 확대될 수 있을 것으로 기대된다.

  • PDF

Axisymmetric large deflection analysis of fully and partially loaded shallow spherical shells

  • Altekin, Murat;Yukseler, Receb F.
    • Structural Engineering and Mechanics
    • /
    • 제47권4호
    • /
    • pp.559-573
    • /
    • 2013
  • Geometrically non-linear axisymmetric bending of a shallow spherical shell with a clamped or a simply supported edge under axisymmetric load was investigated numerically. The partial load was introduced by the Heaviside step function, and the solution was obtained by the finite difference and the Newton-Raphson methods. The thickness of the shell was considered to be uniform and the material was assumed to be homogeneous and isotropic. Sensitivity analysis was made for three geometrical parameters. The accuracy of the algorithm was checked by comparing the central deflection, the radial membrane stress at the edge, or the transverse shear force with the solutions of plates and shells in the literature and good agreement was obtained. The main findings of the study can be outlined as follows: (i) If the shell is fully loaded the central deflection of a clamped shell is larger than that of a simply supported shell provided that the shell is not very shallow, (ii) if the shell is partially loaded the central deflection of the shell is sensitive to the parameters of thickness, depth, and partial loading but the influence of the boundary conditions is negligible.

유냉각기의 열전달 촉진에 관한 연구 (A Study on Heat Transfer Enhancement of Oil Cooler)

  • 조동현;임태우
    • 동력기계공학회지
    • /
    • 제15권3호
    • /
    • pp.25-30
    • /
    • 2011
  • A shell-and-tube oil cooler with plate fins was suggested to improve the defect of the conventional shell-and-tube oil cooler. Experiments were conducted to evaluate the heat transfer performance on the shell side of shell-and-plate finned tube oil cooler with three different tube numbers(9, 13 and 19). Oil flowing on the shell side was cooled by cold water flowing inside the tubes. A shell-and-tube heat exchanger of an oil cooler consisted of one shell pass and two tube passes with the inner tube diameter of 8.82 mm and the tube length of 575 mm. From the experiment of shell-and-tube oil cooler, it was found that the heat transfer coefficient of oil cooler with 9 tubes, as oil flow rate was increased, was approximately 140% and 250% higher than that of 13 and 19 tubes, respectively. The heat transfer coefficient at the water flow rate of $3m^3/h$, also was 120% and 140% higher than that of 2.4 and $1.8m^3/h$, respectively.

게 껍질을 이용한 수중의 중금속 제거 (The removal of heavy metals by crab shell in aqueous solution)

  • 안희경;박병윤;김동석
    • 한국환경과학회지
    • /
    • 제9권5호
    • /
    • pp.409-414
    • /
    • 2000
  • In order to examine the availability and effectiveness of crab shell for the removal of heavy metals in aqueous solution the crab shell was compared with cation exchange resin(CER), zeolite granular activated carbon (GAC) and powdered activated carbon(PAC) on aspects of heavy metal removal capacity rate and efficiency. In the removal of Pb, Cd and Cr, the heavy metal removal capacity of crab shell was higher than those of any other sorbents (CER, zeolite, GAC, PAC) and the order of heavy metal removal capacity was crab shell>CER>zeolite>PAC GAC. However in the removal of Cu, the result of crab shell was slightly lower than that of CER. The initial heavy metal removal rate was affected by the sorts of sorbents and metals. In all heavy metals the heavy metal removal rate of crab shell was higher than those of any other sorbents. Under the heavy metal concentration of 1.0 mmole/$\ell$ the heavy metal removal efficiency of crab shell was maintained as 93~100% which was much higher than those of any other sorbents.

  • PDF

곡률 원판이 결합된 외팔 원통 쉘의 고유진동 해석 (Free Vibration Analysis of a Curvatured Plate Welded to a Clamped-Free Circular Cylindrical Shell)

  • 임정식;손동성
    • 한국소음진동공학회:학술대회논문집
    • /
    • 한국소음진동공학회 2002년도 추계학술대회논문집
    • /
    • pp.529-534
    • /
    • 2002
  • The receptance method was applied for the analysis of a cylindrical shell with a curvaturated plate attached at the top of the shell. The boundary conditions of the shell considered here were clamped at the bottom and free at the top of the shell. Before the analysis of the shell/plate combined structure, the natural frequencies of the plate and the shell were calculated separately and then they were used in the calculation of the frequencies of the combined structure by the receptance method. The frequency equation of the combined structure was derived from the continuity condition at the junction of the shell and the plate. The frequencies for various curvature factors of the plate were presented and compared with those from ANSYS to show its validity of the present method.

  • PDF

Core-shell 구조를 지니는 하모닉 분말의 성형거동 분석 (Effect of Core-Shell Structure on Compaction Behavior of Harmonic Powder)

  • 주수현;박효욱;강수영;이언식;강희수;김형섭
    • 한국분말재료학회지
    • /
    • 제22권2호
    • /
    • pp.105-110
    • /
    • 2015
  • In this study, effect of core-shell structure on compaction behavior of harmonic powder is investigated. Harmonic powders are made by electroless plating method on Fe powders. Softer Cu shell encloses harder Fe core, and the average size of Fe core and thickness of Cu shell are $34.3{\mu}m$ and $3.2{\mu}m$, respectively. The powder compaction procedure is processed with pressure of 600 MPa in a cylindrical die. Due to the low strength of Cu shell regions, the harmonic powders show better densification behavior compared with pure Fe powders. Finite element method (FEM) is performed to understand the roll of core-shell structure. Based on stress and strain distributions of FEM results, it is concluded that the early stage of powder compaction of harmonic powders mainly occurs at the shell region. FEM results also well predict porosity of compacted materials.

자유파수를 이용한 새로운 실린더 운동방정식과 Junger and Feit의 실린더 운동방정식의 비교연구 (A Study of Comparison with Free Wave Number Between a New Cylinderical Wave Equation and the Wave Equation by Junger and Feit)

  • 조형국
    • 한국음향학회지
    • /
    • 제15권6호
    • /
    • pp.47-51
    • /
    • 1996
  • 실린더 운동방정식은 실린더 내에서 발생되는 소음 해석에 매우 중요하다. 그러므로, 지금까지 많은 학자들에 의해 실린더 운동방정식을 유도되었다[1]. 참고문헌[6]에서는, 새로 제안돈 실린더 운동방정식, Junger and Feit의 실린더 운동방정식 그리고 가정해에 의한 선형방정식으로, 실린더가 자유 운동을 할 때, 자유파수를 구하였다. 본 논문에서는 자유파수들의 분산곡선들을 이용하여, 두 실린더운동방정식을 비교하였고, 링주파수와 링확장주파수의 계산으로, 자유파수들의 분산곡선의 물리적인 의미를 부가하였다. 이 결과, 새로 유도된 실린더 운동방정식의 타당함을 보였다. 새로 제안된 실린더 운동 방정식을 이용하면, 산업현장에서, 실린더 내의 고체파에 대한 보다 정확한 분석을 할 수 있을 것으로 사료된다.

  • PDF

Thermal and Mechanical Properties of Waste Ground Nut-shell Reinforced Polyester Composites

  • Prabhakar, M.N.;Shah, Atta ur rehman;Song, Jung-Il
    • Composites Research
    • /
    • 제28권3호
    • /
    • pp.118-123
    • /
    • 2015
  • In the current study explain about the bio-based composites made by groundnut shell as reinforcement with polyester resin matrix. Groundnut shell is an abundantly available natural waste byproduct and poly ester resin is widely used to fabricate of composites for good balance of mechanical properties because it is relatively low price and ease of handling. Evaluate the mechanical properties of manufactured groundnut shell/polyester composites by varying the amounts (wt %) of groundnut shell. Particulate shell reinforced polyester composites incorporating varying amounts of groundnut shell (5, 10, 15 and 20%) were characterized for their tensile strength, flexural strength, and impact strength. The mechanical properties improved with increasing particle loading up to 15% and decreased thereafter. Increasing in strength with increased particle shell loading was attributed to increase in surface area which enhanced load transfer between the polyester matrix and ground shall particulates. Scanning electron microscopic studies have been carried out to study the morphology of the composite. Thermal studies and water absorption properties of the composites also studied in this paper.

부구조물이 있는 유한길이의 쉘 구조물에서의 충격하중에 의한 음향방사 (Acoustic Radiation from a Finite-length Shell with Substructures Subjected to an Impulsive Load)

  • 최성훈
    • 한국소음진동공학회:학술대회논문집
    • /
    • 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
    • /
    • pp.62-67
    • /
    • 1995
  • A method for determining impulsive responses and acoustic radiation for submerged shells of finite length has been presented. The method is a modal-based method, and uses a surface variational principle to obtain data in the frequency domain. The fast Fourier transform technique is used to convert the data to the time domain. The surface pressure responses of a cylindrical shell with endcaps wer compared with those of an infinite shell. It was shown that the surface pressures coincide exactly before any significant reflections from the endcaps occur. Traces of different types of waves were identified from the dispersion relations of the infinite shell. The contributions of flexural and longitudinal waves and these due to the direct radiation from the driving force to the fluid pressure were demonstrated using near-field plots. The exchange of energy between the shell and fluid was examined for shells with and without bulkheads. It was shown that a significant amount of the energy which enters the fluid returns to the shell and most of the energy is dissipated in the shell. It was also shown that the shell with bulkheads radiate significantly more energy into the far-field than the empty shell.

  • PDF