• Journal of the Korean Institute of Gas
• /
• v.8 no.4 s.25
• /
• pp.42-49
• /
• 2004

We study on and simulate the behavior of one-step fixed bed reactor which synthesize DiMethylEther(DME) from Methane. At last, we know that reaction is decreased in case of excess and no cooling because the temperature of reactor is decreased or increased seriously. Also, we study on optimizing the reactor so that we know the optimized operation condition according to cooling effect, space velocity of reactant and temperature of reactant, etc.

• Journal of the Ergonomics Society of Korea
• /
• v.29 no.3
• /
• pp.365-373
• /
• 2010

Many studies on safety issues of human-machine interaction are being conducted, especially taking emergency situations into consideration. In light of this view, the importance of objective and reliable measurement of users' reactions under emergency situations is becoming more important than ever in reflecting such issues in the design of everyday things. However, despite the need to consider the human-machine interactions and human performances at the design stage, there were few studies which considered human performances and behaviors under emergency situations. This study is about an evaluation method and design guide to include such human performances under emergency situations during human-machine interactions. This is achieved through an experiment where operators are instructed to press the emergency button at an experimentally designed location under a random emergency situation. By analyzing the results in a human factors perspective, the response time and the accuracy of the operators' behaviors are explained. Analysis revealed that in designing the center fascia for automobiles, there is a tradeoff between response time and accuracy, and the optimal size of buttons differ in each part of the center fascia. This method is expected to be applicable to industrial situations to derive optimal position for emergency buttons.

• Journal of the Korean Wood Science and Technology
• /
• v.36 no.2
• /
• pp.39-45
• /
• 2008

Formaldehyde and volatile organic compounds (VOCs) are emitted from wood-based panels that have been made using wood particles, wood fiber, wood chips, formaldehyde-based resins and so on. In this study, we examined formaldehyde and total VOCs (TVOC) emission behaviors for plywood overlaid with water-soluble phenolic resin impregnated linerboard (PL), and two kinds of surface materials (decorative veneer and pre-impregnated finishing foil) that were adhered onto the PL that named DPL and PPL. EVA (ethyl vinyl acetate) was used to overlay the decorative veneer and pre-impregnated finishing foil on the plywood with water-soluble phenolic resin impregnated linerboard by a hot press instrument. The debonding test and accelerated aging test were conducted to assess their mechanical properties. Formaldehyde and TVOC emission concentrations were measured using the FLEC method and a VOC Analyzer, respectively. The debonding test results of PL, DPL and PPL were 1.2, 1.5, and $0.5N/mm^2$, respectively. The surface appearance of the samples were not changed after the accelerated aging test. The PL and DPL exhibited reduced formaldehyde and TVOC emission levels, respectively. In the case of PPL, the VOC value was relatively higher than those of PL and DPL.

• Journal of Embryo Transfer
• /
• v.31 no.1
• /
• pp.73-80
• /
• 2016

An in vitro assay following culture of endometrial epithelial cells is essential for understanding epithelial cell function in reproduction. Several diverse techniques have been developed for isolating endometrial epithelial cells, although an optimal technique has not been identified. In this study, we describe a sedimentation-adherence (S-A) isolation technique with a high-yield cell-separating ability to isolate endometrial epithelial cells from 8-week-old female C57BL/6 mice. We analyzed total cell number, viability, morphology, and expression of cytokeratin 18 as an endometrial epithelial cell-specific marker in cells isolated using a mechanical method compared to the S-A technique. There were no significant differences in the total number, viability, or morphology of the putative endometrial epithelial cells with either method. In contrast, significantly more endometrial epithelial cells harvested using the S-A method were positively stained for cytokeratin 18 than those isolated using the mechanical method. These results confirm that the S-A method is more efficient for retrieving endometrial epithelial cells than a mechanical method.

• Parasites, Hosts and Diseases
• /
• v.60 no.6
• /
• pp.401-407
• /
• 2022

Antimalarial drugs play an important role in the control and treatment of malaria, a deadly disease caused by the protozoan parasite Plasmodium spp. The development of novel antimalarial agents effective against drug-resistant malarial parasites is urgently needed. The novel derivatives, SKM13-MeO and SKM13-F, were designed based on an SKM13 template by replacing the phenyl group with electron-donating (-OMe) or electron-withdrawing groups (-F), respectively, to reverse the electron density. A colorimetric assay was used to quantify cytotoxicity, and in vitro inhibition assays were performed on 3 different blood stages (ring, trophozoite, and schizonts) of P. falciparum 3D7 and the ring/mixed stage of D6 strain after synchronization. The in vitro cytotoxicity analysis showed that 2 new SKM13 derivatives reduced the cytotoxicity of the SKM13 template. SKM13 maintained the IC₅₀ at the ring and trophozoite stages but not at the schizont stage. The IC₅₀ values for both the trophozoite stage of P. falciparum 3D7 and ring/mixed stages of D6 demonstrated that 2 SKM13 derivatives had decreased antimalarial efficacy, particularly for the SKM13-F derivative. SKM13 may be comparably effective in ring and trophozoite, and electron-donating groups (-OMe) may be better maintain the antimalarial activity than electron-withdrawing groups (-F) in SKM13 modification.

• Tuberculosis and Respiratory Diseases
• /
• v.70 no.4
• /
• pp.293-300
• /
• 2011

Chronic obstructive pulmonary disease (COPD) is a substantially under-diagnosed disorder, and the diagnosis is usually delayed until the disease is advanced. However, the benefit of early diagnosis is not yet clear, and there are no guidelines in Korea for doing early diagnosis. This review highlights several issues regarding early diagnosis of COPD. On the basis of several lines of evidence, early diagnosis seems quite necessary and beneficial to patients. Early diagnosis can be approached by several methods, but it should be confirmed by quality-controlled spirometry. Compared with its potential benefit, the adverse effects of spirometry or pharmacotherapy appear relatively small. Although it is difficult to evaluate the benefit of early diagnosis by well-designed trials, several lines of evidence suggest that we should try to diagnose and manage patients with COPD at early stages of the disease.

• Clinics in Shoulder and Elbow
• /
• v.17 no.4
• /
• pp.175-180
• /
• 2014

Background: For Neer type IIB fracture of distal clavicle with coracoclavicular ligament injury, various surgical treatments have been used in literatures. However, there was no consensus on the optimal treatment. The aim of this study is to report the clinical and radiological results of open reduction and internal fixation of unstable distal clavicle fracture and suture augmentation of disrupted coracoclavicular ligament. Methods: A prospective study was performed in 23 patients with Neer type IIB distal clavicle fracture in Seoul Medical Center, Eulji Hospital, and National Medical Center. Firstly, suture anchors are inserted in the base of coracoid process and preliminary reduction was achieved by tie-off of three suture limbs around the clavicle. Then, the final fixation was completed with anatomical locking plate. Bony union and the distance between coracoclavicular ligaments were evaluated. Clinical results and complications including stiffness and secondary procedures were evaluated. Results: Bony union was achieved in all cases except one (22 of 23). At mean 14.9 months, no significant difference in the mean coracoclavicular distance was observed compared to uninjured shoulder ($8.2{\pm}7.9mm$ versus $7.3{\pm}3.4mm$, p=0.14). Pain visual analogue scale, American Shoulder and Elbow Surgeons score, Constant score, and Disabilities of the Arm, Shoulder and Hand score were 0.5, 83.4, 78.5, and 6.2, respectively. Revision surgery was performed in one case of nonunion. Four patients who complained of skin irritation underwent implant removal. Conclusions: In cases of an unstable distal clavicle fracture with coracoclavicular ligament disruption, satisfactory clinical results were obtained by locking plate fixation and coracoclavicular ligament suture augmentation concurrently.

• Dementia and Neurocognitive Disorders
• /
• v.17 no.3
• /
• pp.110-119
• /
• 2018

Background and Purpose: To analyze $^{18}F-THK5351$ positron emission tomography (PET) scans of patients with clinically diagnosed nonfluent/agrammatic variant primary progressive aphasia (navPPA). Methods: Thirty-one participants, including those with Alzheimer's disease (AD, n=13), navPPA (n=3), and those with normal control (NC, n=15) who completed 3 Tesla magnetic resonance imaging, $^{18}F-THK5351$ PET scans, and detailed neuropsychological tests, were included. Voxel-based and region of interest (ROI)-based analyses were performed to evaluate retention of $^{18}F-THK5351$ in navPPA patients. Results: In ROI-based analysis, patients with navPPA had higher levels of THK retention in the Broca's area, bilateral inferior frontal lobes, bilateral precentral gyri, and bilateral basal ganglia. Patients with navPPA showed higher levels of THK retention in bilateral frontal lobes (mainly left side) compared than NC in voxel-wise analysis. Conclusions: In our study, THK retention in navPPA patients was mainly distributed at the frontal region which was well correlated with functional-radiological distribution of navPPA. Our results suggest that tau PET imaging could be a supportive tool for diagnosis of navPPA in combination with a clinical history.

• Annals of Occupational and Environmental Medicine
• /
• v.34
• /
• pp.39.1-39.11
• /
• 2022

Background: Workers in logistics centers are always pressed for time to collect and pack products. They also participate in high-intensity manual labor in which various musculoskeletal hazards exist. In the case of logistic center labor, it is estimated that there is a high risk of presenteeism due to the above characteristics which can cause deterioration of workers' mental health. However, there is insufficient research on this topic. Methods: Workers in a logistic center were surveyed using an Internet questionnaire. The survey items included demographic characteristics, labor intensity and work-related factors, and mental health aspects such as depression and anxiety. The survey was conducted for about a month from July 26, 2021 and a total of 353 people were analyzed. Through the χ² test and t-test, the characteristics of workers who experienced presenteeism were examined and the prevalence ratios (PRs) of depression and anxiety experiences were calculated by multivariable Poisson regression. Afterwards, stratification analysis considering gender, the type of contract, and labor intensity was implemented. Results: In the group that experienced presenteeism, the number of working days per week was higher and fixed-term workers, high labor intensity, and sleep deprivation were more common. In the multi-Poisson regression analysis conducted by adjusting the demographic characteristics, working hours, and work-related factors, the PRs of depression and anxiety were 1.98 (95% confidence interval: 1.24-3.18) and 1.81 (1.22-2.68), respectively. In particular, the p-value for interactions was significant when stratified with the type of contract. Conclusions: As a result of the study, presenteeism and mental health were associated in logistic center workers. To prevent mental health issues of logistic center workers, management of presenteeism is necessary and a prospective study is needed.

• Journal of Ginseng Research
• /
• v.46 no.2
• /
• pp.225-234
• /
• 2022

Background: Ginseng, officially known as Panax ginseng Meyer, has been traditionally used as a medicinal herb, particularly in Asia. Ginseng is propagated from seeds; however, seed germination is challenging, especially in its natural environment on farms. The seeds typically exhibit morphophysiological dormancy and require release from both morphological and physiological dormancy before germination. Although some studies have proposed methods for increasing seed germination rates, the underlying mechanisms of its dormancy release process remain unclear. Here, we investigated metabolic alterations during dehiscence in P. ginseng to determine their potential roles in dormancy release. Methods: We compared the ginseng seed metabolome before and after dehiscence and the ginsenoside and phytosterol compositions of the seeds in both periods in the presence of related enzymes. Results: After seed dehiscence, the sugar, amino acid, and squalene concentrations were significantly altered, phytosterols associated with the stigmasterol biosynthesis pathway were increased, while ginsenoside and brassinosteroid levels were not significantly altered. In addition, squalene epoxidase, cycloartenol synthase, 24-methylenesterol C-methyltransferase, and the stigmasterol biosynthesis pathway were activated. Conclusion: Overall, our findings suggest that morphological activities that facilitate ginseng seed growth are the primary phenomena occurring during the dehiscence process. This study improves the understanding of P. ginseng germination processes and promotes further research of its germination and cultivation.