• 한국표면공학회지
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• 제34권5호
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• pp.414-420
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• 2001

A 30-kV plasma immersion ion implantation setup (P $I^3$) has been equipped with a self-developed 6'-magnetron to perform hard coatings with enhanced adhesion by P $I^3$D(P $I^3$ assisted deposition) process. Using ICP source with immersed Ti antenna and reactive magnetron sputtering of Ti target in $N_2$/Ar ambient gas mixture, the TiN films were prepared on Si substrates at different pulse bias and ion-to-atom arrival ratio ( $J_{i}$ $J_{Me}$ ). Prior to TiN film formation the nitrogen implantation was performed followed by deposition of Ti buffer layer under A $r^{+}$ irradiation. Films grown at $J_{i}$ $J_{Me}$ =0.003 and $V_{pulse}$=-20kV showed columnar grain morphology and (200) preferred orientation while those prepared at $J_{i}$ $J_{Me}$ =0.08 and $V_{pulse}$=-5 kV had dense and eqiaxed structure with (111) and (220) main peaks. X-ray diffraction patterns revealed some amount of $Ti_{x}$ $N_{y}$ in the films. The maximum microhardness of $H_{v}$ =35 GN/ $M^2$ was at the pulse bias of -5 kV. The P $I^3$D technique was applied to enhance wear properties of commercial tools of HSS (SKH51) and WC-Co alloy (P30). The specimens were 25-kV PII nitrogen implanted to the dose 4.10$^{17}$ c $m^{-2}$ and then coated with 4-$\mu\textrm{m}$ TiN film on $Ti_{x}$ $N_{y}$ buffer layer. Wear resistance was compared by measuring weight loss under sliding test (6-mm $Al_2$ $O_3$ counter ball, 500-gf applied load). After 30000 cycles at 500 rpm the untreated P30 specimen lost 3.10$^{-4}$ g, and HSS specimens lost 9.10$^{-4}$ g after 40000 cycles while quite zero losses were demonstrated by TiN coated specimens.s.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4072-4083
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• 2022

Ultrasonic impact treatment (UIT) is carried out on the Ni-based alloy stainless steel pipe gas tungsten arc welding (GTAW) girth weld, the differences of microstructure, microhardness and shear strength distribution of the joint before and after ultrasonic shock are studied by microhardness test and shear punch test. The results show that after UIT, the plastic deformation layer is formed on the outside surface of the Ni-based alloy overlayer, single-phase austenite and γ type precipitates are formed in the overlayer, and a large number of columnar crystals are formed on the bottom side of the overlayer. The average microhardness of the overlayer increased from 221 H V to 254 H V by 14.9%, the shear strength increased from 696 MPa to 882 MPa with an increase of 26.7% and the transverse average residual stress decreased from 102.71 MPa (tensile stress) to -18.33 MPa (compressive stress), the longitudinal average residual stress decreased from 114.87 MPa (tensile stress) to -84.64 MPa (compressive stress). The fracture surface has been appeared obvious shear lip marks and a few dimples. The element migrates at the fusion boundary between the Ni-based alloy overlayer and the austenitic stainless steel joint, which is leaded to form a local martensite zone and appear hot cracks. The welded joint is cooled by FA solidification mode, which is forming a large number of late and skeleton ferrite phase with an average microhardness of 190 H V and no obvious change in shear strength. The base metal is all austenitic phase with an average microhardness of 206 H V and shear strength of 696 MPa.

• Medical Lasers
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• 제8권1호
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• pp.13-18
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• 2019

Background and Objectives High-intensity focused ultrasound (HIFU) can produce small zones of thermal damage. A HIFU procedure is non-invasive and it can achieve rejuvenation of facial skin. Fractional CO₂ laser resurfacing delivers thermal damage to the pixilated columnar zone of the skin and so evoke collagen remodeling, the same as HIFU. In many cases, the patients who want rejuvenation with HIFU are also good candidates for cutaneous photorejuvenation such as can be accomplished via fractional CO₂ resurfacing. If patients are treated in a single session by remodeling both the superficial and deep compartments of skin by using both modalities, then improvement in rhytides and tightening of sagging skin will optimize the aesthetic result. Materials and Methods Between May 2014 and January 2018, a total of 44 patients were treated with combination HIFU and fractional CO₂ laser resurfacing according to our protocol. First, the HIFU was applied to the entire face with an average of 300 treatment lines. Immediately after HIFU treatment, the ultrasound gel was washed off and then fractional CO₂ laser resurfacing was performed. We evaluated the patients using 4-point grading scales. The clinician examined the skin for evidence of complications after the completion of treatment. Results All the patients' skin quality showed improvement. Further. the clinical results after duel modality treatment were substantially better than that after the use of either modality alone. The recovery times and the incidence of adverse events when quickly and consecutively performing both treatments were similar as compared to those with employing stepwise treatment. We encountered no complications whatsoever. Conclusion When compared with stepwise therapy, combination therapy with HIFU and fractional CO₂ resurfacing offers better, safer and more effective clinical results. Thus, for targeting multiple layers of aging facial skin, this combination therapy can be safely performed in a single treatment session.

• Geomechanics and Engineering
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• 재33권6호
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• pp.553-565
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• 2023

As the structure of broken rock mass is complex, with obvious discontinuity and anisotropy, it is generally necessary to reinforce broken rock mass using grouting in underground construction. The purpose of this study is to experimentally investigate the mechanical properties of broken rock mass after grouting reinforcement with consideration of the characteristics of broken rock mass (i.e., degree of fragmentation and shape) and a range of reinforcement methods such as relative strength ratio between the broken rock mass and cement-based grout stone body (λ), and volumetric block proportion (VBP) representing the volumetric ratio of broken rock mass and the overall cement grout-broken rock mass mixture after the reinforcement. The experimental results show that the strength and deformation of the reinforced broken rock mass is largely determined by relative strength ratio (λ) and VBP. In addition, the enhancement in compressive strength by grouting is more obvious for broken rock mass with spherical shape under a relatively high strength ratio (e.g., λ=2.0), whereas the shape of rock mass has little influence when the strength ratio is low (e.g., λ=0.1). Importantly, the results indicate that columnar splitting failure and inclined shear failure are two typical failure modes of broken rock mass with grouting reinforcement.

• 한국지구과학회지
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• 제44권6호
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• pp.611-628
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• 2023

이 연구는 경남 고성군 덕명리 일원에 대한 지질 교육적 가치를 탐색하기 위한 것이다. 이를 위하여 이 일대에 대한 야외조사를 통해 퇴적구조(점이층리, 사층리, 연흔, 건열), 해안 퇴적환경(해식애, 파식대지, 자갈 해빈), 상대연령 측정(부정합, 단층, 관입, 포획암) 및 주상절리와 관련된 야외 지질 학습이 가능한 다수의 관찰 지점이 분포하고 있음을 확인하였다. 이후 교육과정의 성취기준 및 교과서의 학습 요소와의 부합 정도를 분석한 결과, 모든 관찰 지점에서 교과서에 제시된 지질학적 특성이 잘 나타나는 전형성을 보여주고 있으며, 동일한 관찰 지점에서 심화학습이 가능한 학습요소를 갖추고 있다는 점에서 지질 교육적 가치가 큰 것으로 평가되었다. 덕명리 일원은 뛰어난 지질 교육적 가치 이외에도 관광 및 교육 인프라가 잘 갖춰져 있는 만큼 안전한 지질 교육을 위한 학습의 장으로서 역할을 할 것으로 기대된다.

• Journal of Veterinary Science
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• 제24권5호
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• pp.49.1-49.15
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• 2023

Background: Hystricomorpha rodents display a similar placentation model to humans. The present study was carried out considering the scarcity of information concerning the placental development in agouti. Objective: Describe the microscopy of the placenta, subplacenta and yolk sac of agoutis in early pregnancy and report on the inversion of the yolk sac. Methods: Fifteen females between the 14^th-32^nd day of gestation were used following euthanasia. Gestational buttons were collected, fixed, processed, stained to optical microscopy or immunohistochemistry. Results: Chorioallantoic placenta (CP) ranged from conical to a half-sphere, as follows: from the 14^th to 17^th day, the CP displays an inverted "V" shape, predominantly formed by cytotrophoblasts; from 20 to 22 days, formed almost entirely by cytotrophoblasts; at 28 days, a half sphere, with distinct lobes and interlobular area, numerous maternal gaps delimited by syncytiotrophoblasts and trophoblast giant cells; at 32 days, globose and undergoing the maturation process. Subplacenta, located between decidua and CP, initially presents septa consisting of simple columnar epithelium and after 17 days, comprising stratified epithelium. Visceral yolk sac (VYS) is attached to two CP projections between 14 and 17 days, formed by a simple cubic epithelium and inverted. Between 20 and 22 days, the epithelium displays apical villous projections with cytoplasmic vacuoles and a vascularized mesoderm. After the 24^th day, the VYS near the placenta is pleated, very vascularized and villous, with decreased villi sizes further away from the placenta. Conclusion: The agouti CP displays similar characteristics to other hystricomorpha, including placenta lobulation, a subplacenta and an inverted vitelline placenta.

• International Journal of Stem Cells
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• 제16권3호
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• pp.269-280
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• 2023

Background and Objectives: The colonic epithelial layer is a complex structure consisting of multiple cell types that regulate various aspects of colonic physiology, yet the mechanisms underlying epithelial cell differentiation during development remain unclear. Organoids have emerged as a promising model for investigating organogenesis, but achieving organ-like cell configurations within colonic organoids is challenging. Here, we investigated the biological significance of peripheral neurons in the formation of colonic organoids. Methods and Results: Colonic organoids were co-cultured with human embryonic stem cell (hESC)-derived peripheral neurons, resulting in the morphological maturation of columnar epithelial cells, as well as the presence of enterochromaffin cells. Substance P released from immature peripheral neurons played a critical role in the development of colonic epithelial cells. These findings highlight the vital role of inter-organ interactions in organoid development and provide insights into colonic epithelial cell differentiation mechanisms. Conclusions: Our results suggest that the peripheral nervous system may have a significant role in the development of colonic epithelial cells, which could have important implications for future studies of organogenesis and disease modeling.

• 지질공학
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• 제34권3호
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• pp.355-366
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• 2024

As the importance of silica is increasing in digital world and other sector, prospecting of silica is the initial process for silica exploration. For prospecting of silica, the Naudanda Quartzite was studied thoroughly. The potential of silica content in the Naudanda Quartzite is presented in very few reports and literatures. Therefore, the study was carried out along the Siddartha Highway and other local roads around the Bhalu Pahad area. The area comprises of mainly phyllite, metasandstone and medium- to coarse-grained orthoquartzite of the Lesser Himalayan metasedimentary sequence. Here orthoquartzite is targeted for the prospecting of silica as quartzite constitutes more than 90% quartz minerals. The study was carried out to prospect the silica resource and compute the mineral reserve in the area. From the route map prepared at 1:2,000-scale along the Bhalu Pahad-Haripala section and columnar section, it is found that the true thickness of the Naudanda Quartzite is 760 m. A geological map was prepared at 1:25,000 scale, and 15 quartzite samples were taken from suitable locations preventing stratigraphical reoccurrence. Five samples were taken randomly from folded zone. Silica grains were counted on the basis of fleet method after thin section preparation of 15 individual samples. More than 95% silica is present on an average. Again, silica content of 5 samples out of 15 were tested chemically and found more than 95% silica concentration. For reserve calculation, silica grade was taken 95% and the reserve was computed on the basis of three cross-sections. It is found that the total volume tonnage is 2.6 billion ton of silica content, and concluded that the silica present in the rock is economic and minable.

• Applied Microscopy
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• 제18권2호
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• pp.1-20
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• 1988

The species of the slug used in the experiment is Limax flavus L. For identifying the chemical characteristics of the epidermis, granules and mucus-producing cell of this animal is examined with methylene blue-basic fuchsin double stain and PAS-alcian blue reagent. For the ultrastructural research of the epidermal free surface, the epitheial cell and the parenchymal cell are used with scanning electron microscope and transmission elec-tron microscope respectively. I . Epidermal tissue The epidermal tissue of the slug is observed being divided into the dorsal and the ventral side(toot pad) respectively. 1) Dorsal epidermal tissue The dorsal epidermis of the slug is constituted with the simple columnar epithelium and the microvilli are compacted on the epidermal free surface. Two different types of the secretory granules of the neutral and the acid mucus are observed between the epithelial cells, and the neutral mucous granules are highest electron-dense but the acid mucous granules are observed to be electron-lucent. 2) Foot epidermal tissue The Foot epidermis is formed with the taller simple columnar epithelium than the dorsal epidermis and these cells have both a large number of the microvilli and a few number of the large villi. The secretory granules of three different types, which are acid, neutral and mixed mucous granule of two different types are observed between the epithelial cells. The neutral mucous granules are highest electron dense but the acid mucous granules are observed to be electron-lucent. II . Mucous granule-producing cell and mucus-producing cells Seven different types of the granules-producing cell and the mucus-producing cells are observed between the parenchyma. 1) A-type of acid mucous granule-producing cell The electron-lucent granules are largely occupied in the cytoplasm of these cells and then the granules are surrounded by irregular membrane. These electron-lucent granules exhibit alcianophilia with PAS-alcian blue reaction, so these granules are certified to be acid mucopolysaccharide. 2) B-type of acid mucus-producing cell The nucleus and the cytoplasm of these cells are pushed by the acid mucus of the electron-lucent toward the cell membrane. This mucus has been confirmed to be the acid mucopolysaccharide with PAS-alcian blue reagent. 3) A-type of neutral mucous granule-producing cell These cells contain the electron-dense round granules with approximately $1{\mu}m$ in diameter, which exhibit strongly PAS-positive reaction. These granules are confirmed to be the neutral mucoplysaccharide. 4) B-type of neutral mucous granule-producing cell These cells contain two different types of electron dense granules and electron-lucent granules; The former exhibits to be strongly PAS-positive and the latter to have alcianophilia reaction respectively. 5) C-type of neutral mucus-producing cell These cells are similar to the shape and the size of the B-type of mucus-producing cell but these two different types of cells are stained with reversing properties to each other. The mucus of the C-type cell that electron-lucent is largely occupied in the cytoplasm that exhibits strongly PAS-positive reaction. 6) D-type of neutral mucous granule-producing cell These cells contain round granules about $1{\mu}m$ in size which are observed to be medium electron-dense granules and those granules are stained brightly red with PAS-weak positive reaction. The granules are certified to be neutral mucopolysaccharide. 7) E-type of neutral mucous granule-producing cell These cells are similar to the shape and the size of the D-type of neutral mucous granule-producing cell. These cells contain a large number of granules with about $1{\mu}m$ in diameter showing electron-lucent and then granules are seen to be PAS-weak positive reaction. III. Parenchyma The clear cell and dark cell are found in the parenchyma of the Limax flavus L. 1) Clear cell These cells are round formed and the nucleus of the cells are larger than cytoplasm. These cells which have the electron-lucent cytosol possess poorly developed organelles. 2) Dark cell These cells are found to be dark cells due to high electron-density, which exhibit strongly methylene-blue reaction from double stain of methylene blue-basic fuchsin.

• 한국수산과학회지
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• 제13권4호
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• pp.125-134
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• 1980

1979년 3월부터 1980년 2월까지 울산 근해에서 채포 수집한 소라, Turbo cornutus를 대상으로 생식세포형성과정 및 생식주기를 조직학적인 방법으로 조사하였다. 1. 소라의 생식소는 패각내 후반부의 표면에 위치하고, 난소와 정소표면은 2층의 피막으로 덮혀 있는데 외층은 단층원주상피세포로 구성되어 있고, 이들 단층원주상피상에는 입방형 혹은 원주형의 점액선세포가 존재한다. 상피세포층의 내층에는 체섬유와 근섬유로 구성된 섬유성피막으로 되어있으며 이 섬유층에서 기원하여 간중장선쪽으로 뻗어나온 소엽상피상에서 시원생식세포들이 형성된다. 2. 난소소엽상피 및 정소소엽상피상에는 eosin에 강하게 염색되는 과립성세포와 미분화간충직들이 영양세포로 관여하고 있으며 이들은 생식소가 발달함에 따라 감소한다. 3. 초기분열증식중인 난원세포는 $10\mu$내외이고 핵은 뚜렷한 인을 가지며 그 크기는 $8\mu$전후이다. 세포질이 점차 충만되면서 그 크기가 $50～60\mu$로 되면 난모세포들은 포도송이 모양으로 난소소엽에 부착한다. 완숙난의 크기는 $180\~210\mu$이며 $10\mu$내외의 gelatin 상피막에 싸여 있다. 4. 방란${\cdot}$방정을 끝낸 생식소는 일부 미방출된 난과 정자의 퇴화흡수가 일어남과 동시에 외측 섬유성 피막으르부터 새로운 소엽상피들이 발달하며 새로운 생식세포를 형성하기 시작한다. 5. 생식조기는 분열증식기, 성畏장기, 성숙기, 방출기 그리고 회복기등의 연속적인 조기로 구분 할 수 있었다. 6. 산란기에는 8월에서 11월까지로 주산란기는 9월부터 10월이었다. 7. 산란기는 지역별 다소 차이 나타내나 거의 수온 $20^{\circ}C$에 전후에 산란성기를 이루고 있어 산란은 수온과 밀접한 관계가 있는 것 같다.