• 한국주조공학회지
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• 제13권1호
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• pp.42-49
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• 1993

Conventional manufacturing process for cast iron-babbitt metal composite is complicate and bimetallic bonding by centrifugal casting is also difficult because their melting point is largely different and nonmetallic inclusion exists on outer shell. This study is aiming to simplify multistage process by adding Cu-powder as insert metals during cast iron solidification. The variables on fabrication of composite pipe are mold rotating speed and inner surface temperature of outer metal. The optimum temperature range for fusion bonding between cast iron and Cu-layer was $1100^{\circ}C-1140^{\circ}C$ in case of mold rotating speed was 700rpm. When the inner surface of Cu-layer was at $900^{\circ}C$, the value of interfacial hardness between Cu-layer and babbitt metal were higher than Cu-matrix by forming diffusion layer, interfacial products between Cu-layer and babbitt metal are proved to be $Cu_6Sn_5({\eta})$by XRD.

• Applied Science and Convergence Technology
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• 제24권2호
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• pp.33-40
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• 2015

$ZrO_2$ and Al-Zr composite oxide film was prepared by vacuum assisted sol-gel dip coating method and anodizing. $ZrO_2$ films annealed above $400^{\circ}C$ have tetragonal structure. $ZrO_2$ layers inside etch pits were successfully coated from the $ZrO_2$ sol. The double layer structures of samples were obtained after being anodized at 100 V to 600 V. From the TEM images, it was found that the outer layer was $Al_2O_3$, the inner layer was multi-layer of $ZrO_2$, Al-Zr composite oxide and Al hydrate. The capacitance of $ZrO_2$ coated foil exhibited about 28.3% higher than that of non-coating foil after being anodized at 100 V. The high capacitance of $ZrO_2$ coated foils anodized at 100 V can be attributed to the relatively high percentage of inner layer in total thickness. The electrical properties, such as withstanding voltage and leakage current of coated and non-coated Al foils showed similar values. From the results, $ZrO_2$ and Al-Zr composite oxide is promising to be used as the partial dielectric of high voltage capacitor to increase the capacitance.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2577-2583
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• 2009

Presented are the formation of iron oxide layers on evaporator tubes in an actual fossil power plant operated under all volatile treatment (AVT) condition and an experimental simulation of iron oxide formation in the presence of ferrous and ferric ions. After actual operations for 12781 and 36326 hr in the power plant, two iron oxide layers of magnetite on the evaporator tubes were found: a continuous inner layer and a porous outer layer. The experimental simulation (i.e., artificial corrosion in the presence of ferrous and ferric ions at 100 ppm level for 100 hr) reveals that ferrous ions turn the continuous inner oxide layer on tube metal to cracks and pores, while ferric ions facilitate the production of porous outer oxide layer consisting of large crystallites. Based on a comparison of the oxide layers produced in the experimental simulation with those observed on the actually used tubes, we propose possible routes for oxid layer formation schematically. In addition, the limits of the proposed corrosion routes are discussed in detail.

• 한국잠사곤충학회지
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• 제14권1호
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• pp.43-47
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• 1972

견층부위별견사의 기계적특성을 파악하고저 Deniroscope와on을 이용하여 실험한바 다음과 같은 결과를 얻었다. 1) 견층별견사의 건조 및 습윤절단강도는 견사섬도감소율에 비례하여 저하한다. 2) 내층견사의 습윤항장력은 외층견사에 대하여 37%로 나타났다. 3) 습윤처리에 의한 전견층의 절단강도(g/d) 31%, 감소하였다. 4) 대섬도당 견사의 건조 및 습윤절단강도는 내층견사가 제일 높았다. 5) Apparent young's modulus는 내층견사에서 증가하였다. 6) 습윤견사의 절단신도는 건조견사에 비해 15% 증가하였다.

• 대한금속재료학회지
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• 제49권2호
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• pp.153-160
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• 2011

The AISI 216L stainless steel with a composition of Fe-16Cr-6Ni-6Mn-1.7Mo (wt.%) was oxidized at $700{\sim}900^{\circ}C$ in air for 100 h. At $700^{\circ}C$, a thin $Mn_{1.5}Cr_{1.5}O_4$ oxide layer with a thickness of $0.4{\mu}m$ formed. At $800^{\circ}C$, an outer thin $Fe_2O_3$ oxide layer and a thick inner $FeCr_2O_4$ oxide layer with a total thickness of $30{\mu}m$ formed. The non-adherent scale formed at $800^{\circ}C$ was susceptible to cracking. At $900^{\circ}C$, an outer thin $Fe_2O_3$ oxide layer and a thick inner $Mn_{1.5}Cr_{1.5}O_4$ oxide layer formed, whose total thickness was $10{\sim}15{\mu}m$. The scales formed at $900^{\circ}C$ were non-adherent and susceptible to cracking. 216 L stainless steel oxidized faster than 316 L stainless steel, owing to the increment of the Mn content and the decrement of Ni content.

• Applied Microscopy
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• 제15권1호
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• pp.71-85
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• 1985

The ultrastructure on the dorsal vessel of 5-day-old cabbage butterfly, Pieris rapae L., was carried out using the transmission and scanning electron microscope. The results are as follows. 1) The aorta. The aorta is simple tubular type and consists of the inner and outer membrane of the myocardium and thick myocardium is located between them. However the inner membrane with $0.26{\mu}m$ thickness and outer membrane with $0.08{\mu}m$ are composed of fibrous materials, the former is composed of low and high densed fibrous materials and the latter appears homogeneous layer. The myocardium consists of typical striated muscles. The sarcomere with $1.6{\mu}m$ length and in cross section, each thick filaments are surrounded by $7{\sim}8$ thin filaments. The intercalated disc is joining the end of the two muscle cells, desmosomes and septate junctions are appeared between the neighboring muscle cells. 2) The heart. The heart composing of myocardium enclosed by its inner and outer membrane as the aorta has a series of well formed segmental chamber. The arrangement of myofilaments, cell adhensions and membrane elements are observed as same as at the aorta. The inner membrane of the heart is deeply invaginated into the myocardium than the outer membrane and a lot of well developed mitochondria with rod shape are aggregated in the folds. The longitudinally and transversely oriented tubule system formed by invagnation of the sarcolemma into the muscle bundle is built up dyad with the sarcoplasmic reticulum as the aorta. The slit is formed by deeply invagination of the inner membrane of myocadium toward the muscle layer and then the inner and outer membrane of myocardium are fused. Therefore, the ostium is formed between the myocardium and situated at the lateral side of the myocardium.

• 한국어류학회지
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• 제13권4호
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• pp.254-260
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• 2001

좀구굴치 성숙란의 난여포층은 외층인 theca cell과 내층인 granulosa cell로 구분되며 특히 원주형인 granulosa cell은 분비활동으로 인하여 세포질에 분비물이 축적되면서 난모세포를 둘러싸게 된다. 이러한 granulosa cell은 난황형성 초기인 난황포 시기에 입방형태를 보이지만 난황구시기에는 원주상세포로 바뀌면서 점액을 분비하는 특징을 보여 주고 있다. 이러한 부착물질은 형태가 없으며 전자밀도가 높다. 또한 이러한 분비물을 가지는 난막은 난황형성이 더욱 진행됨에 따라 동물극 부근이 식물극보다 더욱 두꺼워지고 커지게 된다. 이러한 점막여포층 아래에는 약 $7.8{\sim}11.5\;{\mu}m$ 두께의 방사대가 존재한다. 방사대는 전자밀도가 낮은 외층과 3~5층의 여러 전자밀도층을 가지는 내층으로 구성되어 있다. 한편 점막여포층은 방사대에 존재하지 않고 있기 때문에 이 물질은 난세포질이 여포상피로부터 기원된 것으로 생각된다.

• Korean Journal of Radiology
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• 제22권5호
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• pp.782-791
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• 2021

Objective: To evaluate the signal intensity of the periosteum using ultrashort echo time pulse sequence with three-dimensional cone trajectory (3D UTE) with or without fat suppression (FS) to distinguish from artifacts in porcine tibias. Materials and Methods: The periosteum and overlying soft tissue of three porcine lower legs were partially peeled away from the tibial cortex. Another porcine tibia was prepared as three segments: with an intact periosteum outer and inner layer, with an intact periosteum inner layer, and without periosteum. Axial T1 weighted sequence (T1 WI) and 3D UTE (FS) were performed. Another porcine tibia without periosteum was prepared and subjected to 3D UTE (FS) and T1 WI twice, with positional changes. Two radiologists analyzed images to reach a consensus. Results: The three periosteal tissues that were partially peeled away from the cortex showed a high signal in 3D UTE (FS) and low signal on T1 WI. 3D UTE (FS) showed a high signal around the cortical surface with an intact outer and inner periosteum, and subtle high signals, mainly around the upper cortical surfaces with the inner layer of the periosteum and without periosteum. T1 WI showed no signal around the cortical surfaces, regardless of the periosteum state. The porcine tibia without periosteum showed changes in the high signal area around the cortical surface as the position changed in 3D UTE (FS). No signal was detected around the cortical surface in T1 WI, regardless of the position change. Conclusion: The periosteum showed a high signal in 3D UTE and 3D UTE FS that overlapped with artifacts around the cortical bone.

• 한국식품과학회지
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• 제31권3호
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• pp.771-777
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• 1999

CSLM 기술을 이용하여 Salmonella enteritidis에 의한 계란 오염 과정을 관찰하여 난막의 3중막 구조, cuticle 층 그리고 5가지 필름 피복의 침투 방어효과를 조사하였다. 난막을 구성하는 fiber의 지름은 각각 outer membrane $1.5{\sim}7.2\;{\mu}m$, inner membrane $0.8{\sim}2.0\;{\mu}m$이었고, limiting membrane을 구성하는 입자의 지름은 $0.1{\sim}1.4\;{\mu}m$이었으며, 두께는 각각 평균 10.0, 3.5, $3.6\;{\mu}m$이었다. 난각과 접해 있는 outer membrane은 다음 층인 inner membrane과 부분적으로 중첩되어있고, limiting membrane의 입자들은 매우 밀집되어 inner membrane과 중첩된 상태로 존재하였다. Cuticle층은 전체 계란 표면적 중 $40{\sim}80%$ 를 덮고 있었으며, 두께는 평균 $6.0\;{\mu}m$이었고 피복 필름들의 평균 두께는 자각 mineral oil $5.0\;{\mu}m$, dextrin $3.6\;{\mu}m$, gelatin $3.9\;{\mu}m$, starch $2.5\;{\mu}m$, chitosan $2.2\;{\mu}m$이었다. 필름 피복에 의한 Salmonella enteritidis 생육 억제효과를 관찰한 결과, chitosan이 가장 효과적이었다. 그리고 trisodium phosphate (TSP), cetylpyridinium chloride (CPC) 처리, 5종의 필름 피복 처리와 무처리한 계란표면에 Salmonella enteritidis를 접종한 후 내부 전이 과정을 CSLM을 이용하여 다색영상화(multi-color imaging)와 시간당 투과 균수에 대한 plate count로 비교한 결과, 난각이나 3중막 구조의 난막보다는 cuticle 층이 Salmonella균의 오염을 차단하는데 결정적인 역할을 하는 것으로 나타났으며, chitosan 피복이 cuticle 층과 비슷한 효과를 보였다. 따라서 피복 필름중에서 chitosan이 최외부 방어막인 cuticle층이 결손된 난각 부위를 피복하는데 가장 적합할 것으로 사료된다.

• 한국터널지하공간학회 논문집
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• 제26권3호
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• pp.255-280
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• 2024

쉴드TBM 터널에서 단면 부족이나 큰 변형이 세그먼트 라이닝의 안정성에 우려될 경우 터널 외부에 지반 그라우팅으로 보강하거나 터널 내부에 강판 보강, 링 빔 보강, Inner double layer lining으로 보강하는 경우가 있다. 또한, 기존의 쉴드 TBM 터널의 해석은 세그먼트라이닝의 분절 특성을 고려하지 않는 연속체의 강성일체법으로 해석되어왔다. 본 연구는 내부 강재 라이닝으로 보강한 double layer 보강 단면에 대해 보강 메커니즘을 연구하였다. 본 연구는 세그먼트 라이닝에 대한 모델링을 개선하여 세그먼트 라이닝의 분절 특성을 고려한 분절체 모델링(BJM)을 적용하였고 이를 통해 세그먼트 라이닝의 변형 특성을 반영한 double layer 보강 단면을 해석하였다. 연구 결과 기존 콘크리트 세그먼트 라이닝은 하중을 일정부분 분담하는 역할이 아닌 터널 주변 지반을 보강한 것과 같은 역할을 하였다. 일반적으로, 세그먼트 라이닝의 분절을 고려한 BJM 모델과 분절을 고려하지 않는 강성일체법 모두 하중을 받은 라이닝의 변형 형상과 응력 분포가 유사하게 나타났다. 그러나 하중의 강도가 임계치를 넘는 경우 변형의 양상에 차이가 있으며 변형 특성을 보다 면밀히 검토할 수 있는 것으로 나타났다.