• 한국지반신소재학회논문집
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• 제15권4호
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• pp.43-52
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• 2016

본 논문에서는 지반 시추 시 공벽붕괴 방지를 위해 사용되는 안정액의 다양한 배합비에 따른 공학적 특성에 대한 실험적 연구를 다루었다. 이를 위해 먼저 배합수가 청수일 경우, 안정액의 공학적 특성을 검토하였으며 아울러 해수 배합시 안정액의 공학적 성능 변화에 대한 공학적 특성을 분석하였다. 그 결과, 청수에서 벤토나이트와 폴리머를 추가할 경우 공학적 성능이 향상되는 것으로 나타났으며, CMC에 비해 Polymer의 증점 효과가 우수한 것으로 검토되다. 또한 해수의 경우 벤토나이트에 비해 내염성점토의 내염성 성능이 우수한 것으로 검토되었다. 따라서 본 논문에서는 시공시 배합수에 따른 안정액을 성능에 대한 정성적인 결과를 제시하였다.

• Journal of Chest Surgery
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• 제53권2호
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• pp.49-52
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• 2020

Background: Primary spontaneous pneumothorax is commonly treated with chest tube insertion, which requires hospitalization. In this study, we evaluated the efficacy, costs, and benefits of a portable small-bore chest tube (Thoracic Egg; Sumitomo Bakelite Co. Ltd., Tokyo, Japan) compared with a conventional chest tube. Methods: We retrospectively analyzed all primary spontaneous pneumothorax patients who underwent treatment at Gangnam Severance Hospital between August 2014 and May 2018. Results: A total of 279 patients were divided into 2 groups: the conventional group (n=236) and the Thoracic Egg group (n=43). Of the 236 patients in the conventional group, 100 were excluded because they underwent surgery during the study period. The efficacy and cost were compared between the 2 groups. There was no statistically significant difference between the groups regarding recurrence (conventional group, 36 patients [26.5%]; Thoracic Egg group, 15 patients [29.4%]; p=0.287). However, the Egg group had statistically significantly lower mean medical expenses than the conventional group (433,413 Korean won and 522,146 Korean won, respectively; p<0.001). Conclusion: Although portable small-bore chest tubes may not be significantly more efficacious than conventional chest tubes, their use is significantly less expensive. We believe that the Thoracic Egg catheter could be a less costly alternative to conventional chest tube insertion.

• 한국초전도ㆍ저온공학회논문지
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• 제24권3호
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• pp.24-29
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• 2022

One of the recent proposals with nuclear magnetic resonance (NMR) is a multi-bore NMR which consists of array of magnets which could present possibilities to quickly cope with pandemic virus by multiple inspection of virus samples. Low temperature superconductor (LTS) can be a candidate for mass production of the magnet due to its low price in fabrication as well as operation by applying the helium zero boil-off technology. However, training feature of LTS magnet still hinders the low cost operation due to multiple boil-offs during premature quenches. Thus in this paper, LTS magnet with low mechanical stress is designed targeting the "training-free" LTS magnet for mass production of magnet array for multi-bore NMR. A thorough process of an LTS magnet design is conducted, including the analyses as the followings: electromagnetics, mechanical stress, cryogenics, stability, and protection. The magnet specification was set to 4.7 T in a winding bore of 85 mm, corresponding to the MR frequency of 200 MHz. The stress level is tolerable with respect to the wire yield strength and epoxy crack where mechanical disturbance is less than the minimum quench energy.

• 비파괴검사학회지
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• 제33권4호
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• pp.368-375
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• 2013

소구경 배관 용접부 손상은 원자력발전소에서 빈번하게 발생되고 있는 문제이며, 이러한 손상은 보수를 위한 불시정지를 야기하고 결과적으로 발전소에 경제적인 손실을 초래한다. 따라서 소켓용접부의 제작결함 검출과 초기 성장 결함의 검출은 매우 중요하다고 할 수 있다. 지금까지 해당부위에 대한 검사는 ASME Code Section XI 요건에 의하여 표면검사를 적용하여 왔으나 강화검사로 체적검사기법인 초음파검사를 병행하여 수행하고 있다. 그러나 가동중에 발생되는 피로균열을 검출하기 위하여 적용되고 있는 일반 수동 초음파검사는 소켓용접부의 접근성과 초음파 탐촉자의 접촉 문제 등으로 인하여 검사 결과의 신뢰성에 문제가 있어 왔다. 본 연구에서는 위상배열 초음파검사 기술을 적용하여 소구경 배관 소켓용접부의 검사 신뢰성과 속도를 향상하고자 하였다. 이를 위하여 소구경 배관 소켓용접부 검사를 위한 3.5 MHz 위상배열 초음파 탐촉자를 제작하고 탐촉자의 접촉 조건과 일정한 신호 품질을 유지하기 위하여 수동 엔코더 스캐너를 개발하였다. 또한 검사 시스템을 구성하고 현장 검사를 위한 절차서도 개발하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.1024-1025
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• 2004

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.419-420
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• 2002

The piston-cylinder mechanism is widely adopted in the hydraulic machine components. In these cases, the hydrodynamic pressures are generated in the clearance gap between the piston and cylinder under lubrication action of the oils. Under the eccentric condition of the piston in the cylinder bore, the asymmetric pressure distributions in the circumferential direction result in lateral forces on the piston. When the lateral forces act as increasing the piston eccentricity, excessive wear can be occurs in the cylinder bore and piston. In this paper, the hydrodynamic pressures generated in the clearance are measured using a stationary piston and moving cylinder apparatus. The experimental results showed that the hydrodynamic pressure distributions are highly affected by the eccentricity of the piston.

• 대한기계학회논문집
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• 제8권1호
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• pp.65-70
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• 1984

A recursive parameter estimation method is applied to spindle deflection model during boring process. The spindle infeed rate is then determined to preserve the diametral tolerance of bore. This estimation method is further extended to adaptive control by application of the variance perturbation method. The results of computer simulation attest that the proposed method renders the optimal cutting conditions, maintaining the diametral accuracy of bore, regardless of parameter fluctuations. The proposed method necessitating only post-process measurements features that initialization of parameter guess values in simple, a priori knowledge on parameter variations is not needed and the accurate estimation of optimal spindle infeed rate is obtained, even if the parameter estimation may be poor.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.310-311
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• 2002

We designed a large bore superconducting solenoid as a source of magnetic field inside liquid-nitrogen-jacketed liquid helium dewar. The diameter of the sample space in the dewar is about 10.0 cm. Considering the space for thermal insulation between liquid helium and the sample tube, the solenoid bobbin has been designed to be 12.0 cm and the most inner layer of the solenoid 13.0 cm. The desired uniformity of the field, which is ~ $\pm$0.1％ of the central field amplitude deviation within ~5.0$^2$$\times$3.6 ㎤ with the shortest dimension along the solenoidal axis, restricted the length of the solenoid to be at least 41.14 cm.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.431-438
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• 1999

Vertical congressive and horizontal pile load tests were performed to a instrumented large diameter (D : 1,000 mm) drilled shaft. A drilled shaft was penetrated into the weathered soil and weathered rock. PMT was done for evaluation of properties for these strata. It was expected to be difficult to get undisturbed samples of weathered soils and rocks. Thus. PMT was done at the several selected depths. In those strata, to prevent the test bore hole from collapsing, bentonite slurry was used for making the test bore hole. In this study. soil properties was evaluated by means of PMT results and estimating method (direct method, the Memard method) of vertical pile capacity and horizontal pile behaviors were summarized. Also, vertical and horizontal pile capacity were calculated using PMT and pile load test results.

• 한국환경과학회지
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• 제6권2호
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• pp.183-187
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• 1997

유기인제 농약을 70% acetone으로 추출한 다음 dlchloromethane 층으로 옮겨 추출물을 florisil로 충진된 open-column에서 chromatography를 행하였다. 마지막 추출물을 nitrogen-phosphorus detector(GC/NPD)을 가진 GC로 분석하였다. Narrow-bore capillary GC(Ultra-2)에 대해 18 가지의 유기인제 농약의 회수율이 88.7%에서 100.0%에 달하였다. 본 분석 방법의 최소 검출 준위는 0.019 - 0.035 mg/kg 이었으며 sample throughput(추출, open-column chro-matography 및 GC 분석)도 상당히 개선되었다.(sample당 8시간)