• 한국재료학회지
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• 제13권9호
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• pp.593-597
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• 2003

Anodic aluminum oxide (AAO) membrane was made of aluminum sheet (99.6%, 0.2 mm thickness). The regular array of hexagonal nano pores or channels were prepared by two step anodization process. A detail description of the AAO fabrication is presented. After the 1st anodization in oxalic acid (0.3 M) at 45 V, The formed AAO was removed by etching in a solution of 6 wt% $H_3$$PO_4$＋1.8 wt% $H_2$$CrO_4$. The regular arrangement of the pores was obtained by the 2nd anodization, which was carried out in the same condition as the 1st anodization. Subsequently, the alumina barrier layer at the bottom of the channel layer was removed in phosphoric acid (1M) after removing of aluminum. Pore diameter, density, and thickness could be controlled by the anodization process parameters such as applied voltage, anodizing time, pore widening time, etc. The pore diameter is proportional to the applied voltage and pore widening time. The pore density and thickness can be controlled by anodization temperature and voltage.

• 한국재료학회지
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• 제12권1호
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• pp.89-93
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• 2002

To investigate the effect of properties of pores in anodic alumina template(AAT) on the formation and characteristics of metal nano wires, Cu and Ni nano wires were manufactured using anodic alumina template formed in various electrolytes. The characteristics of prepared metal nano wires using AAT could be replicated from those of pores in AAT. The diameters of nano wires could be controlled by the widening process of anodic porous film in $H_3PO_4$ solution. The shape ratio of the nano wire was shown to be $170{\pm}30$ for Ni nano wire formed by AAT made in sulfuric acid.

• 한국전기전자재료학회논문지
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• 제21권5호
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• pp.415-420
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• 2008

AAO films were fabricated on two kinds of substrates such as $Al/SiO_2/Si$ and Al/Ni/Ti/Si. To obtain well-aligned AAO film, we optimized process condition for buffer layer, electrolyte and voltage. In the case of oxalic acid, the AAO film with pore size of approximately 45 nm was obtained at voltage of 40 V, temperature of $10^{\circ}C$, oxalic acid of 0.3 M and widening time of 60 min. Then the thickness of barrier is less than 600 nm. In the case of sulfuric acid, the AAO film has pore size of 40 nm and barrier thickness of 400 nm with optimum conditions such as voltage of 25 V, temperature of $8^{\circ}C$, sulfuric acid of 0.3 M and widening time of 60 min.

• 펄프종이기술
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• 제33권5호
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• pp.37-44
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• 2001

Fracture toughness was considered as one of the good estimates of the paper break tendency of paper web in the press room. Paper break on the paper machine is caused by many factors such as paper machine irregular vibrations, impurities in the fiber furnish, shives, and so on. On the paper machine, the solid content of paper web is changing very rapidly from less than 1% to over 95%. We tried to measure the fracture toughness of paper web at different solid contents for providing the fundamental knowledge of paper break. Stretches of wet web were also measured and compared to the fracture toughness changes. Four different fiber furnishes (SwBKP, HwBKP, ONP, and OCC) were refined to different degrees, and at different solid contents (40%, 60%, 80% and 95%), their fracture toughnesses were measured. Two fracture toughness measurement methods (essential work of fracture and Tryding's load-widening method) were used, and we found they gave identical results. The stretch curves of the wet webs against the axis of solid contents were very similar to the fracture toughness curves of those.

• Journal of Chest Surgery
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• 제23권3호
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• pp.465-473
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• 1990

Glutaraldehyde have been used as the most effective cross-linking agent for stabilizing collagen fibers and preventing biodegradation. We processed bovine pericardium in a solution containing 0.625% glutaraldehyde,0.05M HEPES buffer and 0.26% magnesium chloride in saline. The glutaraldehyde-preserved bovine pericardium was implanted in 36 patients at Seoul National University Hospital during a 11-month period between May 1989 and March 1990. 24 were males and 12 females, with ages ranging from 6 months to 168 months [mean age of 43 months]. In 12 patients, the glutaraldehyde-preserved bovine pericardium was used for orthotopic reconstruction of the pericardial sac. In 24 patients. the glutaraldehyde-preserved bovine pericardium was heterotopically implanted.; pulmonary monocusp implant and RVQT [right ventricular outflow tract] patch widening were performed in 10 patients, pulmonary monocusp implant in 6, RVOT patch widening in 4, valved conduit in 2, conduit and pulmonary angioplasty in 1, and ventricular septation in l. With vascular suture techniques, the anastomoses were immediately tight. There was no bleeding from the needle holes and no oozing through bovine pericardium itself. During the follow-up period of up to 10 months, no infections of the glutaraldehyde-preserved bovine pericardium occurred and no bovine pericardium-related complications were observed in this series.

• 한국재료학회지
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• 제12권7호
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• pp.533-539
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• 2002

Porous anodic aluminum oxide layer for nano templates was prepared in acidic solutions. In order to investigate effects of 2nd anodization on ordered formation behaviors of the porous oxide layers, electrochemical and microstructural studies were performed, primarily using TEM, FE- SEM, AFM, and Ultramicrotomy. The pore diameter of the anodic oxide layer increased approximately linearly with increasing voltages, and to the contrary, the pore density decreased. It was shown that 2nd anodizing on the cell base after dissolving 1st anodic oxide layer was remarkably effective for forming ordered array of the pores, comparing with the case for 1st anodization only. And for controlling the diameter of pores, widening method by chemical dissolution seemed more practical than by electrochemical methods.

• 한국지형학회지
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• 제24권4호
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• pp.103-115
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• 2017

This paper shows the types of deteriorated hiking trails and degrading factors at three Great Walks such as Tongariro Alpine Crossing, Routeburn Track and Kepler Track in New Zealand. The deteriorated trails could be classified into gullying, widening, narrowing, branching and sidewall erosion. Department of Conservation carefully manages overland flows on trails for preventing surface erosion, thus the Great Walks show only a minor problem of gully on trails which is usually active in a mountainous area. Widening and branching of trails caused by tread erosion are not also developed due to the restriction of visitors as well as the management of rainwash. However, despite the detailed maintenance and prevention of an overuse of trails, some trails traversing steep slopes in a alpine zone under a periglacial environment are severely degraded along their sidewalls. It suggests that a unvegetated sidewall of trails has to be strictly managed in an early stage of occurrence and a slope-traversing section should be selected with more consideration when establishing a route of hiking trails.

• Acta Via Serica
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• 제6권1호
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• pp.55-90
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• 2021

In the last several decades, and especially since the Chinese launching of the Belt and Road (BRI) initiative in 2013, the Chinese presence in Central Asia has intensified. Russia and Chinese leaders deny that there is any conflict of interests between them, while the standard narrative has been that the two states adhere to a functional division of tasks in which China concentrates on economic activity while Russia acts as the security guarantor for the region. This article argues that the professed equanimity between the Russian and Chinese leaderships masks the emergence of widening cracks in their relationship with regard to Central Asia. The convenient narrative of a functional division of tasks between the two states is called into question by China's increasingly active presence in the military and security sector in the region, but China's influence is growing throughout the Central Asian economic, political, and social order. China's movement into Central Asia challenges Russia's claim to act as an equal partner of China, as well as its pretensions to regional hegemony. This development reflects the widening disparity between the two states with respect to their power capabilities but it also exposes the interactions between Russia and China in Central Asia as the most vulnerable aspect of their relationship. In Central Asia, a defensive Russia encounters an ascendant China.

• 대한관절경학회지
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• 제10권2호
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• pp.165-172
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• 2006

목적: 자가 슬괵건을 이용한 관절경하 전방십자인대 재건술시 이식건의 경골측 골 터널내 고정의 유용성을 이차 관절경 검사의 추시 관찰을 통하여 평가 하고자 하였다. 대상 및 방법: 1999년 12월부터 2005년 5월까지 자가 슬괵건을 이용한 전방 십자인대 재건술을 시행한 환자 중 이차 관절경 검사를 시행한 32례를 대상으로 하였다. 경골측의 고정방법에 따라 나사못 실고정만을 시행한 군(제 1군)과 나사못 실고정과 간섭나사를 이용한 경골측 골 터널내 고정을 함께 시행한 군(제 2군)으로 구분하였다. 이차 내시경 추시 관찰시의 평균 나이는 30세였으며 남자가 30례, 여자가 2례였고 전방십자인대 재건술 후 이차 관절경 검사를 시행한 기간은 평균 21.3개월이었다. 결과는 마취하의 KT-1000 관절계와 IKDC 분석 및 경골측 골 터널의 크기와 Telos 스트레스 부하 검사를 방사선학적으로 평가하였으며, 이차 관절경 소견의 평가 또한 시행하였다. 결과: 평가한 IKDC분석 및 Telos스트레스 부하 방사선 검사상의 전이 정도와 KT-1000 관절계상의 전이정도는 제2군에서 우수한 소견을 보였으나, 통계적으로 의미 있는 차이를 보이진 않았다. 관절 내시경상의 이식건의 긴장도, 이식건의 육안 소견, 이식건의 활액막 증식 정도도 제2군에서 우수한 소견을 보였으나, 통계적으로 의미 있는 차이를 보이진 않았다. 전후면 방사선 사진상 경골측의 골터널의 확장은 제1군에서 2.3 mm 및 제2군에서 1.7 mm로 측정되어 통계적으로 의미 있는 차이를 보였다(P=0.042). 결론: 자가 슬괵건을 이용한 십자 인대 재건술에서 경골측 골 터널내 고정의 부가하는 시술은 경골측 골터널의 확대를 의미 있게 감소 시켰으나 수술 후의 임상적 결과, 관절의 동요 정도, 관절경적 소견에 있어 유의한 차이는 보이지 않았다. 본 연구에서 경골측 고정을 위해 나사못 실고정 단독으로 사용하여도 만족스러운 임상적 결과, 관절의 안정도, 이식건의 성숙을 얻을 수 있었고 경골측 골터널의 확대는 결과에 영향을 미치지 않는다는 것을 알 수 있었다.

• Advances in pediatric surgery
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• 제8권1호
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• pp.16-22
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• 2002

초음파 검사는 수술 전 탈장 진단을 위한 안전하고 간편한 진단방법으로 본 연구에서는 서혜부 탈장의 진단 시 초음파 검사의 정확도와 잠복 탈장에 대한 초음파의 진단적 의의를 확인하고자 하였다. 1999년 3월부터 2000년 1월까지 경북대학교 일반외과학 교실에서 이학적 검사상 서혜부 탈장이 의심되어 술 전 확인을 위해 초음파 검사를 실시한 82명의 남아 (편측성 70예, 양측성 12예)를 대상으로 하였다. 서혜부 탈장 확진을 위한 초음파 검사의 진단 기준은 1)장관 탈장, 2)교통성 음낭수종, 3)초상돌기 확장, 즉 내서혜륜 부위에서 초상돌기의 너비가 4 mm 이상되는 경우로 하였다. 서혜부 탈장의 임상적 증상이 있었던 94개서의 서혜부에 대한 초음파 검사 결과, 장관 탈장 31개 (33%), 교통성 음낭수종 18개 (19%), 초상돌기 확장 38개 (41%), 탈장이 없는 경우가 7개 (7%)였다. 임상적 증상이 없었던 70개소의 서혜부는 초음파 검사상 장관 탈장 4개 (6%), 5개 (7%), 교통성 음낭수종, 초상돌기 확장 11개 (16%), 탈장이 없는 경우가 50개 (70%) 였다. 편측성 탈장의 증상을 가진 환아 중 20예 (28%) 가 초음파 검사에서 이학적 검사상 발견되지 않은 반대측 탈장이 발견되었으며 이들 중 5 개 (7%)는 탈장 없는 것으로 진단되었다. 양측성 탈장을 가진 12예 중 2예가 초음파 검사상 편측성 탈장으로 진단되었다. 초음파 검사상 서혜부 탈장으로 진단된 모든 예에서 서혜부 탈정 교정수술을 시행하였다. 164개소의 서혜부 중 이학적 검사에 의해 137개가 정확하게 진단되었으며 27개가 오진이었으므로 이학적 검사의 정확도는 83.5%였다. 탈장 교정수술을 시행한 107개의 서혜부 중 초음파 검사상 탈장으로 정확하게 진단된 경우는 104개이고 오진된 경우는 3예로 초음파 검사의 정확도는 97.2% 였다. 초상돌기 확대의 경우는 탈장의 증상이 있었던 38개소 중 36개, 증상이 없었던 11개 중 10개로 잠복 탈장의 경우 초음파 진단의 민감도는 93.8%였다. 서혜부 탈장의 진단에 있어 초음파 검사는 비침습적이며 높은 정확도를 가진 진단 방법으로 이미 임상적 검사상 확진된 탈장의 경우 간과하고 지나갈 수 있는 반대측 서혜부 탈장의 진단에 유리하며 본 연구와 같이 내서혜륜의 정상 직경의 상한을 4 mm로 정하면 술 전에 잠복 탈장을 비교적 쉽게 진단할 수 있어 불필요한 반대측 탈장 교정 수술을 줄일 수 있는 장점이 있다. 이에 서혜부 탈장이 의심되는 환아에 있어 상용 검사로 초음파 검사를 제안하는 바이다.