소경 굴참나무 횡절 원판의 강제송풍천연건조

이준우 ( Joon Woo Lee ),강춘원 ( Chun Won Kang ),박로원 ( Ro Won Park ),강호양 ( Ho Yang Kang ) 한국목재공학회 2015 목재공학 Vol.43 No.1

소경 참나무 횡절목을 열처리하여 브로치 등 악세사리용 소재로 개발하였다. 그러나 국산참나무는 난건조수종으로 특히 횡절 원판을 건조결함없이 건조하기 어렵다. 소경 굴참나무(Quercus variabilis)에서 얻은 원판(섬유방향 길이7 mm)을 여름과 가을에 강제송풍천연건조하면서 여러 조건에 따른 건조수율을 조사하였다. 같은 조건에서 가을에 건조한 시편의 최종 평균함수율이 여름에 건조한 시편의 평균함수율보다 낮았다. 두 계절 모두 큰 직경의 시편은 풍속에 따른 차이를 보이지 않았으나 작은 직경의 시편은 풍속이 높았을 때 최종 평균함수율이 약간 낮았다. 두 계절 모두 직경이 큰 시편의 할렬 발생빈도가 직경이 작은 시편보다 높았는데 가을에는 2배 정도인데 반해 여름에는 4배가 넘었다. 여름에 낮은 풍속에서 건조한 큰 직경 시편의 할렬 발생빈도가 높은 이유는 여름의 높은 습도와 낮은 풍속으로 반복적인 수분 응축과 증발이 일어났기 때문으로 설명할 수 있다. Cross-cut disks from small diameter oak logs were thermally modified and developed to make accessories such as a brooch. However it is known that domestic oaks are refractory and it is hard to dry their cross-cut disks without any drying defects. The cross-cut disks of Quercus variabilis (7 mm long in the longitudinal direction) were forced to dry in air at two different air velocities in summer and fall season, and their drying yields were investigated. Under the same condition, the average final moisture contents (MCs) of the specimens dried in the fall were lower than those dried in the summer. The average final MCs of the small diameter specimens dried at higher air velocity were slightly lower than those at lower air velocity while those of the large diameter specimen were not influenced by the air velocity. The number of the large diameter specimens with cross checkings was higher than that of the small diameter specimen. This discrepancy between two different diameters was twice in the fall, while it was more than four times in the summer. The large diameter specimens dried at low air velocity in Summer were cross-checked most, which was attributed to repeated water condensation and evaporation due to high humidity and low air velocity.

Heparin Immobilization of Tissue Engineered Xenogeneic Small Diameter Arterial Scaffold Improve Endothelialization

Tardalkar Kishor,Marsale Tejesh,Bhamare Nilesh,Kshersagar Jeevitaa,Chaudhari Leena,Joshi Meghnad G. 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.3

BACKGROUND: Autologous vessels graft (Inner diameter\6 mm) harvesting always challenged during bypass grafting surgery and its complication shows poor outcome. Tissue engineered vascular graft allow to generate biological graft without any immunogenic complication. The approach presented in this study is to induce graft remodeling through heparin coating in luminal surface of small diameter (Inner diameter\1 mm) decellularized arterial graft. METHODS: Decellularization of graft was done using SDS, combination of 0.5% sodium dodecyl sulfate and 0.5% sodium deoxycholate and only sodium deoxycholate. Decellularization was confirmed on basis of histology, and DAPI. Characterization of extracellular matrix was analyzed using histology and scanning electron microscopy. Surface modification of decellularized vascular graft was done with heparin coating. Heparin immobilization was evaluated by toluidine blue stain. Heparin-coated graft was transplanted end to end anastomosis in femoral artery in rat. RESULTS: Combination of 0.5% sodium dodecyl sulfate and 0.5% Sodium deoxycholate showed complete removal of xenogeneic cells. The heparin coating on luminal surface showed anti-thrombogenicity and endothelialization. Mechanical testing revealed no significant differences in strain characteristics and modulus between native tissues, decellularized scaffolds and transplanted scaffold. Collectively, this study proposed a heparin-immobilized ECM coating to surface modification offering functionalize biomaterials for developing small-diameter vascular grafts. CONCLUSION: We conclude that xenogeneic decellularized arterial scaffold with heparin surface modification can be fabricated and successfully transplanted small diameter (inner diameter\1 mm) decellularized arterial graft.

한성기 백제 송풍관 연구

한지선(Han Ji Sun),김태우(Kim Tae Woo),정낙현(Jeong Nak Hyeon),곽병문(Kwak Byeong Moon),이은우(Lee Eun Woo) 중부고고학회 2016 고고학 Vol.15 No.3

본고는 최근 제철유적 발굴 조사의 증가에 따라 백제 제철유적에서 출토된 곡관형 송풍관 분석을 통해 당시 제철기술의 단면을 살펴보고자 하였다. 송풍관이란 송풍장치(풀무)와 제련로·단야로 등의 가마를 연결해 주는 매개체로 노 내에 바람을 불어 넣어 고온을 형성시키는 역할을 한다. 연질의 토제품으로 직경의 크기에 따라 소·중·대·특대형으로 나누어지며, 중구경 이상에서는 다시 곡관형과 직관형으로 나뉘는데 가마에 직접 삽입되는 관은 곡관형 송풍관이다. 곡관형 송풍관은 대개 120-140°의 각을 보이며 노 내로 들어가는 선단부와 노 바깥의 후단부로 나뉜다. 형식은 선단부의 형태와 후단부의 제작기법 흔적에 의해 구분되는데, 선단부는 내만형(A), 직립형(B), 외반형(C)으로 백제 송풍관은 내만형과 직립형이 확인된다. 후단부의 경우 제작기법과 관련된 것으로 후단부에 실이나 짚과 같은 재료를 말아 놓은 원형의 틀 위에서 제작한 흔적이다. 틀 흔적이 잔존한 경우는 내면, 바닥, 외면 중 어디에 틀을 대어 성형하였는가로 구분해 볼 수 있다. 송풍관의 태토분석결과 별도의 내화토 성분이 검출되지 않았으며 토기 태토와 동일하다는 점을 확인할 수 있었다. 한편 유물의 제작흔적 검토를 통해 실제 실험으로 제작기법을 복원하였는데 특히 곡관형 송풍관의 곡관부 성형은 일체 성형과 분할 성형으로 나뉠 수 있지만 분할 성형이 제작하기에 용이하다는 것이 확인되었다. 송풍관의 거치방식은 노 내벽의 용융면의 흔적과 노 보수흔적이 다수인 부위 관찰 등을 통해 찾을 수 있으며, 사용 온도는 진천 석장리 유적에서 송풍관 선단부가 잔존한 경우가 많고, 그것을 재현한 실험의 결과를 통해 볼 때 1,200~1,400℃ 전후한 온도 대에 조업했을 가능성이 높다. 그러나 고온에 오랜 시간 노출될 경우 녹지 않을 수 없기 때문에 온도대와 함께 조업시간대도 영향을 미치는 중요한 요인이 된다. This paper tried to study the iron production technology of Baekje Dynasty using the tuyere excavated from Baekje iron archeological site while the number of successful excavation of iron archeological site is increasing recently. The tuyere is used to create high temperature in the kilns, such as smelting furnace or smithery hearth that produces ironware, by blowing the wind into them and it is classified into large-diameter, medium-diameter, and small-diameter tuyere. The large-diameter tuyere is again classified into bent pipe and straight pipe and it is the bent pipe that is directly inserted into the furnace. The bent pipe typically has 120-140°angle and it is divided into fore-end part that is inserted into the furnace and rear-end part outside the furnace. Their types are divided into two kinds such as non-frame type (I) and frame type (II) depending on the manufacturing technique of the rear-end part. The frame type is subdivided again depending on which part, among the inner side, floor, and outer side, the frame was placed on for molding. Because the small-diameter types were excavated only in small quantity, they were classified based on their forms connected from the fore-end part to rear-end part but we expect that we can get more detailed information when the number of data increases in the future. As the result of tuyere clay analysis, the fire clay elements were not detected and we could reconfirm that the tuyere clay was the same clay as general earthenware clay. This study also restored the manufacturing technique of the tuyere through actual experiment by examining the production trace of the relic. The molding of the bent pipe part of the large-diameter bent pipe type tuyere can be divided into integrated molding and split molding but in general, the split molding was identified to be easier technique for production. The installation method of the tuyere could be identified by the trace of the melting side at the furnace wall and it could be also identified through the experiment that the iron production work is very much likely to have conducted at around 1,200~1,300℃ temperature if the fore-end part was not melted as indicated by the relics of Seokjang-ri, Jincheon. The tuyere is found not only in Baekje area but also in Silla and Gaya areas where many similar cases of using rear-end part frames are identified. This study will proceed with the comparative research on iron production technologies in Three Kingdoms period by expanding the research materials in the future.

Challenges and Advances in Materials and Fabrication Technologies of Small-Diameter Vascular Grafts

Mei‑Xian Li,Qian‑Qi Wei,Hui‑Lin Mo,Yu Ren,Wei Zhang,Huan‑Jun Lu,정윤기 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

The arterial occlusive disease is one of the leading causes of cardiovascular diseases, often requiring revascularization. Lack of suitable small-diameter vascular grafts (SDVGs), infection, thrombosis, and intimal hyperplasia associated with synthetic vascular grafts lead to a low success rate of SDVGs (< 6 mm) transplantation in the clinical treatment of cardiovascular diseases. The development of fabrication technology along with vascular tissue engineering and regenerative medicine technology allows biological tissue-engineered vascular grafts to become living grafts, which can integrate, remodel, and repair the host vessels as well as respond to the surrounding mechanical and biochemical stimuli. Hence, they potentially alleviate the shortage of existing vascular grafts. This paper evaluates the current advanced fabrication technologies for SDVGs, including electrospinning, molding, 3D printing, decellularization, and so on. Various characteristics of synthetic polymers and surface modification methods are also introduced. In addition, it also provides interdisciplinary insights into the future of small-diameter prostheses and discusses vital factors and perspectives for developing such prostheses in clinical applications. We propose that the performance of SDVGs can be improved by integrating various technologies in the near future.

Physical-Mechanical Properties of Glued Laminated Timber Made from Tropical Small-Diameter Logs Grown in Indonesia1

Rahma Nur Komariah,Yusuf Sudo Hadi,Muh Yusram Massijaya,Jajang Suryana 한국목재공학회 2015 목재공학 Vol.43 No.2

The aim of this study was to determine the physical and mechanical properties of glued laminated timber (glulam) manufactured from small-diameter logs of three wood species, Acacia mangium (mangium), Maesopsis eminii (manii), and Falcataria moluccana (sengon), with densities of 533, 392, and 271 kg/m 3 , respectively. Glulam measuring 5 cm by 7 cm by 160 cm in thickness, width, and length, respectively, was made with three to five lamina, or layers, and isocyanate adhesive. The glulams contained either the same wood species for all layers or a combination of mangium face and back layers with a core layer of manii or sengon. Solid wood samples of the same size for all three species were included as a basis for comparison. Physical-mechanical properties and delamination tests of glulam referred to JAS 234:2003. The results showed that the properties of same species glulam did not differ from those of solid wood, with the exception of the shear strength of glulam being lower than that of solid wood. Wood species affected glulam properties, but three- and five-layer glulams were not different except for the modulus of elasticity. All glulams were resistant to delamination by immersion in both cold and boiling water. The glulams that successfully met the JAS standard were three- and five-layer mangium, five-layer manii, and five-layer mangium-manii glulams.

시멘트풀의 영향을 고려한 축소모형 매입말뚝의 거동분석

박종전,정경자,정상섬 한국지반공학회 2017 한국지반공학회논문집 Vol.33 No.1

Skin friction may be one of the most critical factors in designing the prebored and precast pile. Special attentionwas given to the interface behavior of cement milk-surrounding soil during the installation of prebored and precast pile. Small-scale field model pile test was conducted for the case of single pile. The size and geometry of the small-scalefield model piles were designed with pile length 1.3m, boring diameter 0.067 m. Quick maintain-load test was conductedfor the cases of boring diameter 150, 125, 90, 86, 74 mm and water-cement ratio 90, 70, 60%. It was shown thatthe bearing capacity of the pile increased as the cement-water ratio and cement milk thickness increased. Consideringthe scale effect between the small-scale model test and the actual construction site, it was found that cement milkthickness of 0.1∼0.4D (50∼200 mm) was reasonable for the stability of the structure. Also, the proper cement pastewater / cement ratio was about 70% when considering the results of this study and quality control.

국산 미이용 소경재의 과초산 전처리 조건별 화학적 특성 평가

김민아(Min-Ah Kim),강주원(Ju-Won Kang),정민욱(Min-Wook Jeong),이신아(Sinah Lee),양봉숙(Bong Suk Yang),정명준(Myung-Joon Jeong),강규영(Kyu-Young Kang) 한국펄프·종이공학회 2015 한국펄프·종이공학회 학술발표논문집 Vol.2015 No.4

약산 전처리 조건에 따른 소경 신갈나무 유래 푸르푸랄 및 레불린산의 함량 변화

장수경 ( Soo Kyeong Jang ),정한섭 ( Han Seob Jeong ),홍창영 ( Chang Young Hong ),김호용 ( Ho Yong Kim ),류가희 ( Ga Hee Ryu ),여환명 ( Hwanmyeong Yeo ),최준원 ( Joon Won Choi ),최인규 ( In Gyu Choi ) 한국목재공학회 2015 목재공학 Vol.43 No.6

본 연구에서는 국산 소경 신갈나무를 이용하여 약산 전처리를 실시하고, 당으로부터 변환된 푸르푸랄 및 레불린산의 함량 변화를 평가하였다. 약산 전처리는 반응온도(140-180℃), 반응시간(10-30분), 황산 촉매 농도(0-2%, w/w)에 따라 수행하였고, 전처리 후 액상 내 글루코오스, XMG (자일로오스 + 만노오스 + 갈락토오스), 푸르푸랄, 레불린산의 함량을 측정/분석하였다. 글루코오스는 반응온도의 상승, 반응시간과 황산 촉매 농도의 증가에 의해 그 함량이 높아져최대 16.02%까지 나타났으나, 황산 촉매 농도 2% (반응온도 170℃ 이상, 반응시간 20분 이상)에서 함량이 감소하였다. 한편, XMG 함량은 반응온도의 영향을 크게 받았고, 반응온도와 황산 촉매 농도의 증가에 따라 1.63%까지 감소하였으며, 반응시간의 증가에 의한 함량변화는 적었다. 푸르푸랄 함량은 반응온도, 반응시간, 황산 촉매 농도 증가에 따라 높아져 초기시료 중량 대비 최대 7.61% (반응온도 180℃, 반응시간 20분, 1% 황산 촉매 농도)로 나타났으나, 전처리 조건이 최대 푸르푸랄 함량 조건보다 가혹해지면서 감소하는 경향이 발생하였다. 레불린산 함량은 반응온도, 반응시간, 황산 촉매 농도가 증가함에 따라 높아졌고, 특히 반응온도 170℃ 이상에서 급격한 함량 증가를 확인하였으며, 최대 10.98% (반응온도 180℃, 반응시간 30분, 2% 황산 촉매 농도)로 나타났다. 반면 황산 촉매를 투입하지 않았을 경우 모든 반응온도, 반응시간 조건에서 푸르푸랄 및 레불린산 함량은 1% 미만으로 나타났다. In this study, dilute acid pretreatment was operated using small-diameter Quercus mongolica for evaluating the yield change of furfural and levulinic acid depending on pretreatment factors. The dilute acid pretreatment was conducted depending on reaction temperature (140-180℃), reaction time (10-30 min), and sulfuric acid concentration (0-2%, w/w). Then, glucose, XMG (xylose + mannose + galactose), furfural, and levulinic acid contents in the liquid hydrolyzate were measured and analyzed after pretreatment. Glucose content increased to 16.02% as reaction temperature, reaction time, and sulfuric acid concentration increased, but it decreased at the sulfuric acid concentration of 2% (reaction temperature: > 170℃, reaction time: > 20 min). On the other hand, reaction temperature had a strong influenced on XMG content, and XMG content decreased to 1.63% through increasing of reaction temperature and sulfuric acid concentration, but XMG content was less affected by changes of reaction time. Furfural content increased with the increase of reaction temperature, reaction time, and sulfuric acid concentration, and maximum furfural content was 7.61% (reaction temperature: 180℃, reaction time: 20 min, sulfuric acid concentration: 1%) based on a weight of raw material, while furfural content was dropped in more severe condition than in maximum furfural content condition. Levulinic acid content also increased with higher reaction temperature, reaction time, and sulfuric acid concentration. Especially, the sharp increase of levulinic acid content was observed above 170℃, and maximum levulinic acid content was 10.98% (reaction temperature: 180℃, reaction time: 30 min, sulfuric acid concentration: 2%). However, less than 1% of furfural and levulinic acid content was obtained in non-acidic catalyst condition that in whole conditions of reaction temperature and reaction time.

내경 1.77 mm관내 R-22와 R-410A의 응축열전달

노건상(Geon-Sang Roh),손창효(Chang-Hyo Son) 한국가스학회 2008 한국가스학회지 Vol.12 No.1

본 연구는 세관내 R-22와 R-410A의 응축 열전달 계수를 실험적으로 조사하였다. 냉매 순환루프의 주요 구성품은 수액기, 변속 액펌프, 질량유량계, 증발기(예열기), 응축기(시험부)로 구성된다. 시험부는 평활, 수평 동관으로 내관의 내경과 외경이 각각 1.77 mm와 3.38 mm이다. 냉매 질량유속은 450~1050 kg/(m<SUP>2</SUP>s)이고, 입출구 평균건도는 0.05~0.095이다. 주요 실험결과를 요약하면, 응축 열전달 계수는 질량유속과 건도이 증가할수록 증가하였고, R-410A의 응축 열전달 계수가 R-22에 비해 약간 높았다. 종래의 상관식과 비교한 결과, 저건도와 저질량유속을 제외하고는 실험값과 종래의 상관식으로 예측한 값의 차이가 큰 것으로 나타났다. The condensation heat transfer coefficients of R-22 and R-410A in a small diameter tube were investigated. The main components of the refrigerant loop consist of a receiver, a variable-speed pump, a mass flowmeter, an evaporator (preheater), and a condenser (test section). The test section consists of smooth, horizontal copper tube of 3.38 mm outer diameter and 1.77 mm inner diameter. The refrigerant mass fluxes varied from 450 to 1050 kg/(m<SUP>2</SUP>s) and the average inlet and outlet qualities were 0.05 and 0.95. The main results were summarized as follows : the condensation heat transfer coefficient also increases with increasing mass flux and quality. The condensation heat transfer coefficient of R-410A was slightly higher than that of R-22. Most of correlations proposed in the large diameter tube showed significant deviations with experimental data except for the ranges of low quality and low mass flux.

저관경 온수 배관을 이용한 초박형 온돌시스템의 방열특성 평가

이미화(Lee Mi-Hwa),최경석(Choi Gyoung-Seok),강재식(Kang Jae-Sik) 한국건축친환경설비학회 2007 한국건축친환경설비학회 학술발표대회 논문집 Vol.- No.-

The energy-saving policies of the government to reduce the environmental load, such as global warming caused by greenhouse gases and the high oil prices in recent years is highlighting the importance of the energy consumption and efficiency of the ondol system. Accordingly, various studies are underway to develop a new ondol system and increase on-site application with the aim of reducing the energy consumption of buildings which account for about 30% of domestic energy consumption. The purpose of this study is to develop an super slim type ondol system capable of heating at a relatively lower temperature by eliminating the imbalance of floor temperature, which is the weakness of the most common wet-type ondol, and increasing the radiation capacity per unit area. In this study small-diameter hydraulic heating pipes, which replace the existing hydraulic heating pipes 20㎜ in diameter, were installed at interval of 75㎜. A unit model experiment was conducted to evaluate the thermal performance and pipes by examining the radiation characteristics according to the hot water supply temperature and supply flow.