• 한국진공학회지
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• 제19권3호
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• pp.169-176
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• 2010

크라이오 펌프는 크기에 비해 상대적으로 높은 배기속도를 나타내어 경제적이지만 흡착 패널의 온도에 민감하게 반응하는 배기성능 측면에서 볼 때 대유량 및 펄스 기체 부하에 대한 성능 유지 및 회복능력은 의문의 여지가 있다. 크라이오 펌프의 기체부하에 대한 공식적인 성능지표로는 최대배기량(max. throughput)과 교차(crossover)값이 있고 공식적인 것은 아니지만 펌프 회사에서 제공하는 사양에는 대부분 아르곤 회복시간(Ar recovery time)이라는 지표가 들어 있으며 사양서에 제시하지는 않지만 걸프(gulp) 시험도 통상 시행한다. 이들은 겉보기에 서로 다르지만 한편으로는 서로 중복되거나 연관성을 가지고 있다. 따라서 실용적인 면에서 절차들을 비교, 검토 및 개선하고 때에 따라서는 적절히 결합할 수 있는 방안에 대해 모색하려고 한다.

• Journal of Preventive Medicine and Public Health
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• 제34권1호
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• pp.35-40
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• 2001

Objectives : To elucidate the transient effects on the risk of occupational injuries as acute events and establish so alternative proposal. Methods : The study population comprised a total of 302 workers randomly selected from applications for occupational injury compensation reported to the Inchon local labor office from January 1. 1999 to December 31. A case-crossover design, where each case serves its own control, was applied to this study. Through a telephone interview, workers provided useful data concerning five job related stressful events such as company transfer, work load change, overtime work, exchange duty, and work-part transfer. They were asked whether there were stressful events within a week of the occurrence of injury and the degree of stress. Exposure status from one year prior was used as control information. In the end, the data provided by 158 of selected persons was used for the analysis based on the quality of the data provided by the participants. A conditional logistic regression was used to discover the transient effects on the risk of occupational injuries as acute events. Results : The effects a company transfer and work load change on occupational injury was statistically significant on the risk of occupational Injuries as an acute event(RR=5.5, 95% CI=2.501-12.428; RR=3.1, 95% CI=1.963-5.017, respectively). Other stressful events were found to elevate the risk factor for the occurrence of occupational jujury, but were not significant. Conclusions : Our results suggested that transient stressful events elevated the risk factor for the occurrence of occupational injury.

• 한국전자파학회논문지
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• 제18권1호
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• pp.1-6
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• 2007

본 논문에서는 출력단 전력의 위상과 크기가 모두 대칭인 새로운 구조의 3-way 전력 분배기를 제안한다. 종래의 일반적인 Wilkinson 전력 분배기의 경우, 3-way 이상의 전력 분배시 격리 특성을 결정하는 저항 소자의 crossover로 인하여 평면형 구조로의 구현이 어려웠다. 반면, 본 논문에서 제안하는 회로는 평면형이면서 격리 저항을 쉽게 장착할 수 있는 장점을 가지고 있다. 그리고 대칭 구조이면서 선로 간 전기적 길이가 동일하므로 출력단 위상차를 위한 별도의 보상 선로가 불필요하다. 제작된 2.4 GHz 대 3-way 전력 분배기는 종래의 구조에 비하여 160% 만큼 개선된 $S_{11}$ 대역폭, 최하22.4 dB의 격리 특성, 그리고 출력 단자간 동일한 위상 특성을 보인다.

• 디자인학연구
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• 제17권3호
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• pp.449-460
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• 2004

최근에 스포츠유틸리티 차량이 점차 대중화되고 있다. 이것은 과거의 단순한 승용차 중심의 자동차 소비구조에서 보다 다양화 된 생활양식에 따라 보다 전문화 된 성능의 차량에 대한 수요가 늘어난 이유에서 인 것으로 보인다. 이러한 수요변화는 주 5일 근무에 의한 여가시간의 증가와 생활수준 향상에 따른 레저활동의 요구 증가 등도 원인이지만, 차량 자체의 성능향상과 차종 다양화 역시 중요한 요인으로 작용하고 있다. 자동차 발전의 역사 초기부터 다양한 유형의 다목적 차량들이 개발되고 사용되어오고 여는데, 이들은 미국의 $\ulcorner$지프$\lrcorner$에서 발전된 차량이 주류를 이루고 있다. 이 차량들은 여러 메이커들을 통해 각각의 기능적 전문성을 살린 다양한 정통적 유형과 복합개념의 차량들로 개발되고 있다. 복합개념의 차량들은 전반적으로 소형화를 추구하는 반면, 정통적 형태의 4륜 구동차량들은 대형화 및 고성능화 되는 양방향의 경향이 동시에 나타나고 있다. 향후에 이러한 경향은 다양한 메이커와 차종에서 확대되어 나타나게 될 것으로 예측된다.

• 대한약리학회지
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• 제31권2호
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• pp.261-269
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• 1995

Background; To explore the efficacy of aspartate as NAD regenerating agent for ethanol and acetaldehyde oxidation, we performed crossover challenge in two groups of volunteers by coadministration of various doses of aspartate, asparagine and ethanol. Methods; 18 healthy male volunteers were randomly divided into two groups. 6 volunteers of the first group were administered 5 gm monosodium aspartate(MSA), 5 gm asparagine or placebo with 100 ml of $40^{\circ}$ whiskey by the 3 way-crossover design, while 12 volunteers of the other group were administered placebo, 1, 2 or 5 bottles of $Aspar^(circledR)$ containing 1 gm of MSA per bottle with 100 ml of $40^{\circ}$ whiskey by the 4 way-crossover design. Ethanol(and acetaldehyde) concentrations in venous blood drawn at 0, 0.25, 0.5, 1, 2, 4, 8th hour after ethanol ingestion were analysed by gas chromatogaphy. Subjective symptoms, liver function tests and psychomotor function tests were also performed during the study periods. Result; Plasma concentration and AUC of acetaldehyde in asparagine and MSA trials on ethanol ingestion were significantly lower than those of placebo trial in the 1st group. Plasma ethanol concentration of 5 bottle $Aspar^(circledR)$ trial was significantly lower than that of placebo trial in the 2nd group. Improvement of subjective symptoms or psychomotor performance by the treatment was not statistically significant. Conclusion; Aspartate and asparagine may be prospective candidates for acceleration of ethanol metabolism and prevention of ethanol toxicity.

• 한국항해항만학회지
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• 제31권7호
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• pp.605-611
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• 2007

In order to become a mega hub port, major ports all over the world are making every effort to enhance their productivity through efficiency of internal operation. Accordingly, in order to enhance the competitiveness of a container terminal, an automated container terminal is considered as the best alternative. An automated container terminal is using such automated handling equipment as AGV(Automated Guided Vehicles) and ATC(Automated Transfer Crane). The efficient equipment operation plays a critical role in enhancing the productivity of an automated container terminal. In an automated container terminal, the most important equipments are AGV and ATC. Each block of containers with a vertical layout is generally operating two ATCs. The two ATCs can be crossed or not at each block. In the case of operating crossover ATC, it has an advantage of high flexibility that ATC work is possible at both TP(Transfer Point) of each block. But it has also a disadvantage that the yard has to be operated at a low storage level of containers in the terminal yard. Recently, for automated container terminals, which are being prepared for opening in Korea, they plan to use uncrossed twin ATC in order to make the storage level of their yards high at a low cost. Therefore, studies have to be made in order to increase the efficiency of twin ATC system based on the flexibility that the crossover ATC system has. This research aims to suggest an operation strategy to improve efficiency of twin ATC at each storage block in a yard.

• Journal of Preventive Medicine and Public Health
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• 제45권4호
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• pp.219-226
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• 2012

Objectives: To evaluate the risk of fractures related with zolpidem in elderly insomnia patients. Methods: Health claims data on the entire South Korean elderly population from January 2005 to June 2006 were extracted from the Health Insurance Review and Assessment Service database. We applied a case-crossover design. Cases were defined as insomnia patients who had a fracture diagnosis. We set the hazard period of 1 day length prior to the fracture date and four control periods of the same length at 5, 10, 15, and 20 weeks prior to the fracture date. Time independent confounding factors such as age, gender, lifestyle, cognitive function level, mobility, socioeconomic status, residential environment, and comorbidity could be controlled using the case-crossover design. Time dependent confounding factors, especially co-medication of patients during the study period, were adjusted by conditional logistic regression analysis. The odds ratios and their 95% confidence intervals (CIs) were estimated for the risk of fracture related to zolpidem. Results: One thousand five hundred and eight cases of fracture were detected in insomnia patients during the study period. In our data, the use of zolpidem increased the risk of fracture significantly (adjusted odds ratio [aOR], 1.72; 95% CI, 1.37 to 2.16). However, the association between benzodiazepine hypnotics and the risk of fracture was not statistically significant (aOR, 1.00; 95% CI, 0.83 to 1.21). Likewise, the results were not statistically significant in stratified analysis with each benzodiazepine generic subgroup. Conclusions: Zolpidem could increase the risk of fracture in elderly insomnia patients. Therefore zolpidem should be prescribed carefully and the elderly should be provided with sufficient patient education.

• Journal of Chest Surgery
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• 제54권1호
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• pp.53-58
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• 2021

Background: We aimed to investigate the characteristics of primary spontaneous pneumothorax (PSP) in adolescents and to analyze the relationship between the occurrence of PSP and air pollutants. Methods: Data pertaining to age, sex, body mass index, smoking status, initial pneumothorax volume, presence of bullae, treatment methods, and city of residence were retrospectively obtained from January 2010 to December 2014. We investigated the association between short-term exposure to air pollutants (SO2, NO2, O3, CO, and PM10) and the occurrence of PSP using a case-crossover design with conditional logistic regression. Results: We collected information from 598 patients who were admitted for PSP, with a mean follow-up duration of 62.9 months. The majority (91.1%) of the patients were male. In the case-crossover design, conditional logistic regression showed that no air pollutant was associated with the occurrence of pneumothorax. The results were consistent across all city subgroups (Anyang, Gunpo, Uiwang, and Gwacheon). Conclusion: In our study, the incidence rate of pneumothorax was 153.8 per 100,000 person-years in male adolescents and 16.7 per 100,000 person-years in female adolescents. The case-crossover design showed that PSP in adolescents is unlikely to be related to air pollution.

• Bulletin of the Korean Chemical Society
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• 제21권3호
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• pp.281-290
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• 2000

We varied recombination method of fenetic algorithm (GA), i.e., crossover step, to compare efficiency of these methods, and to find more optimum GA method. In one method (A), we select two conformations(parents) to be recombined by systematic combination of lowest energy conformations, and in the other (B), we select them in a ratio proportional to the energy of the conformation. Second variation lies in how to select crossover point. First, we select it randomly(1). Second, we select range of residues where internal energy of the molecule does not vary for more than two residues, select randomly among such regions, and we select either thr first (2a) or the second residue (2b) from the N-terminal side, or the first (2c) or the second residue (2d) from the C-terminal side in the selected region for crossover point. Third, we select longest such hregion, and select such residue(as cases 2) (3a, 3b, 3c or 3d) of the region. These methods were tested in a 2-dimensionl lattice system for 8 different sequences (the same ones used by Unger and Moult., 1993). Results show that compared to Unger and Moult's result(UM) which corresponds to B-1 case, our B-1 case performed similarly in overall. There are many cases where our new methods performed better than UM for some different sequences. When cooling factor affecting higher energy conformation to be accepted in Monte Carlo step was reduced, our B-1 and other cases performed better than UM; we found lower energy conformers, and found same energy conformers in a smaller steps. We discuss importance of cooling factor variation in Monte Carlo simulations of protein folding for different proteins. (A) method tends to find the minimum conformer faster than (B) method, and (3) method is superior or at least equal to (1) method.

• Advances in nano research
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• 제13권3호
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• pp.259-267
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• 2022

Two-dimensional (2D) transition metal carbides/nitrides or "MXenes" belong to a diverse-class of layered compounds, which offer composition- and electric-field-tunable electrical and physical properties. Although the majority of the MXenes, including Ti₃C₂T_x, are metallic, they typically show semiconductor-like behaviour in their percolated thin-film structure; this is also the most common structure used for fundamental studies and prototype device development of MXene. Magnetoconductance studies of thin-film MXenes are central to understanding their electronic transport properties and charge carrier dynamics, and also to evaluate their potential for spin-tronics and magnetoelectronics. Since MXenes are produced through solution processing, it is desirable to develop deposition strategies such as inkjet-printing to enable scale-up production with intricate structures/networks. Here, we systematically investigate the extrinsic negative magnetoconductance of inkjetprinted Ti₃C₂T_x MXene thin-films and report a crossover from weak anti-localization (WAL) to weak localization (WL) near 2.5K. The crossover from WAL to WL is consistent with strong, extrinsic, spin-orbit coupling, a key property for active control of spin currents in spin-orbitronic devices. From WAL/WL magnetoconductance analysis, we estimate that the printed MXene thin-film has a spin orbit coupling field of up to 0.84 T at 1.9 K. Our results and analyses offer a deeper understanding into microscopic charge carrier transport in Ti₃C₂T_x, revealing promising properties for printed, flexible, electronic and spinorbitronic device applications.