• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제32권4호
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• pp.363-371
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• 1996

The Steering and Sailing Rules of International Regulations for Preventing Collisions at Sea now in use direct the best aid - action to avoid collision by the stand - on vessel. But these rules do not refer to the safety relative distance between two vessels when she should take such action. In this paper, the author analyzed the ship's collision avoiding actions from the viewpoint of ship motions and worked out mathematical formulas to calculate the relative distances necessary for taking action to avoid collision. Figuring out the values of maneuvering indices through experiments of 11 actual ships of small, medium, large and mammoth size, the author applied these values to the calculating formulas and calculated the minimum relative distances. The main results are as follows: 1. It was confIrmed that the stand - on vessel should keep the greatest relative distance for taking best aid - action to avoid collision when the cross angle of course was $90^{\circ}$ and near it(70-$90^{\circ}$ ). 2. When the cross angle of course was $90^{\circ}$ , the minimum relative distance of small vessel(GT: 160-650tons) was found to be more than about 6.8 times of her own length, and those of medium(GT : 2,300-3,500tons), large(GT : 22,OOO-62,OOOtons) and mammoth(GT : 91,000-139,000tons) vessels were found to be more than about 9.0 times, about 5.4 times and about 6.8 times of their own lengths. 3. It was confIrmed that collision danger was greater when crossing angle was obtuse than in an acute angle, therefore greater relative distance was to be kept by the stand - on vessel for taking best aid - action to avoid collision in the case of the obtuse angle. 4. In every vessels, in the case of $90^{\circ}$ cross angle of course the safety minimum relative distance was found to be more than about 9.0 times of their own lengths.

• Health Policy and Management
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• 제15권1호
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• pp.97-117
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• 2005

This study was designed to compare the differences m results of supervisor and subordinate rating. Data was collected from personnel evaluation and subordinate rating results for middle managers(n=68) in hospital from 3rd January to 20th March in 2004. Supervisor rating consisted of performance, ability and attitude evaluation. Subordinate rating consisted of leadership, ability and attitude evaluation. Collected data included sociodemographic characteristics, work department, work level, years of work, years at present level and whether working in a patient serving department. The difference of standardized supervisor and subordinate rating score was used to define groups as 'higher in supervisor rating group'. Groups were defined in total score, ability score and attitude score. Main results were as follows: 1. In total score, sectional chiefs were apt to be 'higher in subordinate rating group' while chief clerks were apt to be 'similar group' or 'higher in supervisor rating group'. Staffs in patient serving department were likely to be 'higher in supervisor rating group' and staffs in non-patient serving department were likely to be 'higher in subordinate rating group'. All these results were statistically significant. 2. In ability score, there were no statistically significant differences in age, sex, years of education, work department, work level, years of work and whether working in a patient serving department among 'higher in supervisor rating group', 'similar group' and 'higher in subordinate rating group'. 3. In attitude score, staffs in the department of medical affairs and the department of administration were apt to be 'higher in subordinate rating group'. Staffs in the department of nursing were apt to be 'higher in supervisor rating group'. Staffs in a patient serving department were likely to be 'higher in supervisor rating group' and staffs in a non-patient serving department were likely to be 'higher in subordinate rating group'. All these results were statistically significant. 4. Logistic analysis about total score showed that sectional chiefs had higher Odds Ratio(OR) to be in 'higher in subordinate rating group'. Staffs in a non-patient serving department had higher OR to be in 'higher in subordinate rating group'. Both these results were statistically significant. 5. Logistic analysis about ability score showed that sectional chiefs had higher OR to be in 'higher in subordinate rating group'. Staffs in a non-patient serving department had higher OR to be in 'higher in subordinate rating group'. These results were not statistically significant. 6. Logistic analysis about total score showed that sectional chiefs had higher OR to be in 'higher in subordinate rating group', but the difference was not statistically significant. Staffs in a non-patient serving department had significantly higher OR to be in 'higher in subordinate rating group'. In conclusion, there is no clear superiority between supervisor and subordinate rating in personnel evaluation. It would be better to use a mixed model. It's also suggested to use an intervening rate of application or scores considering work levels and work department in personnel evaluation. These results would be helpful for hospitals planning a supervisor and subordinate rating system for personnel evaluation.

• Journal of the Korean Society for Marine Environment & Energy
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• 제9권2호
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• pp.109-119
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• 2006

This study investigated the effect of artificially enhanced mesozooplankton on the phytoplankton dynamics during fall blooming period using a mesocosm in Jangmok bay located in the Southern Sea of Korea in 2001. The four bags with 2,500 liter seawater containment were directly filled with the ambient water. And then, abundances of mesozooplankton in two experimental bags were treated 6 times higher than those in control bags by towing with net($300{\mu}m$) through the ambient water. Phytoplankton community between control and experimental bags were not significantly different in terms of chlorophyll-a(chl-a) concentration and standing crop (one-way ANOVA, p>0.05) during the study period. Initial high standing crop and chl-a concentration of phytoplankton drastically decreased and remained low until the end of the experiment in all bags. Diatoms, accounting for most of the phytoplankton community, consisted of Skeletonema costatum, Pseudo-nitzschia seriata, Chaetoceros curvisetus, Ch. debilis, Cerataulina pelagica, Thalassiosira pacifica, Cylindrotheca closterium, and Leptocylindrus danicus. Noctiluca scintillans dominated the temporal variation of mesozooplankton abundances, which peaked on Day 10 in the control and experimental bags, while the next dominant copepods showed their peak on Day 7. Shortly after mesozooplankton addition, copepod abundance in the experimental bags was obviously higher than that in the control bags on Day 1, however, it became similar to that in the control bags during the remnant period. It was supported by the higher abundance and length of both ctenophores and hydromedusae in experimental bags relative to the control bags. However, the cascading trophic effect, commonly leading to re-increase of phytoplankton abundance, was not found in the experimental bags, indicating that copepods were not able to control the phytoplankton in the bags based on the low grazing rate of Acartia erythraea. Besides that, rapidly sunken diatoms in the absence of natural turbulence as well as N-limited condition likely contributed the no occurrence of re-increased phytoplankton in the experimental bags.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.783-791
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• 2015

A fluidized-bed reactor with an inside diameter of 0.1 m and a height of 1.2 m was used to study the effect of steam and catalyst additions to air-blown biomass gasification on the production of producer gas. The equipment consisted of a fluidized bed reactor, a fuel supply system, a cyclone, a condenser, two receivers, steam generator and gas analyzer. Silica sand with a mean particle diameter of $380{\mu}m$ was used as a bed material and calcined dolomite ($356{\mu}m$), which is effective in tar reduction and producer gas purification, was used as the catalyst. Both of Korea wood pellet (KWP) and a pellet form of EFB (empty fruit bunch) which is the byproduct of Southeast Asia palm oil extraction were examined as biomass feeds. In all the experiments, the feeding rates were 50 g/min for EFB and 38 g/min for KWP, respectively at the reaction temperature of $800^{\circ}C$ and an ER (equivalence ratio) of 0.25. The mixing ratio (0~100 wt%) of catalyst was applied to the bed material. Air or an air-steam mixture was used as the injection gas. The SBR (steam to biomass ratio) was 0.3. The composition, tar content, and lower heating value of the generated producer gas were measured. The addition of calcined dolomite decreased tar content in the producer gas with maximum reduction of 67.3 wt%. The addition of calcined dolomite in the air gasification reduced lower heating value of the producer gas. However The addition of calcined dolomite in the air-steam gasification slightly increased its lower heating value.

• The Korean Journal of Mycology
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• 제44권1호
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• pp.23-30
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• 2016

This study was conducted for comparison of ingredients, phytochemical compounds and antioxidant activity of Wofiporia extensa cultured in Gangwon-do, Gyeongsang-do, and Jeolla-do. Three contents of Wofiporia extensa were analyzed as oxygen (46~48%), carbon (38~39%), hydrogen (6.05~6.1%) and nitrogen (0.17~0.21%). The mineral contents of 50% ethanol Wofiporia extensa extracts were measured as sulfur (S) 145~149 ppm, Magnesium (Mg) 69~72 ppm, phosphorus (P) 122~154 ppm and calcium (Ca) 210.61~509.98 ppm. Wofiporia extensa from Gyeongsang-do (509.98 ppm) contained a significantly higher quantity of Ca than that from Gangwon-do (210.62 ppm) and Jeolla-do (223.88 ppm). In the gas chromatograph-mass spectrometry (GC-MS) analysis, oleic acid was identified in three 50% ethanol Wofiporia extensa extracts. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay for antioxidant activity, the $IC_{50}$ values of Wofiporia extensa cultured in Gangwon-do, Gyeongsang-do and Jeolla-do were calculated as 2.966 mg/mL, 23.03 mg/mL, and 4.16 mg/mL and 3.521 mg/mL, 12.17 mg/mL, and 7.40 mg/mL. In the ferric reducing antioxidant power (FRAP) assay, the $IC_{50}$ values of Wofiporia extensa cultured in Gangwon-do, Gyeongsang-do, Jeolla-do were 6.585 mg/mL, 19.06 mg/mL, and 18.97 mg/mL, respectively. In summary, Wofiporia extensa cultured in Gangwon-do had stronger antioxidant activity and higher concentration of oleic acid than that of Geyongsang-do and Jeolla-do. However, Wofiporia extensa cultured in Geyongsang-do contained a much higher concentration of Ca than that of Gangwon-do and Jeolla-do.

• Journal of the Korean Institute of Landscape Architecture
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• 제41권1호
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• pp.1-11
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• 2013

In nature, to change the consciousness of those who wish to pursue something new, the road is turning function-oriented 'Walking Path' into purpose-oriented 'Walking Trails'. Though 'Walking Trails' is a long linear journey that leads people to see, to feel and to experience while walking on the trail, but considering on the landscape of trails when selecting routes is lacking. Landscapes, which are felt and perceived while walking on the trail, provide a purpose, and can be an important factor to improve visitor satisfaction. However, the study is insufficient in terms of landscape of trails. Therefore, it is the purpose of this study to find ways to help improving visitors' satisfaction in selecting routes, by analyzing the images and preferences of trails landscapes that are visually perceived, by analyzing the correlation between visitors' satisfaction and them. For this study, landscape assessment was carried out after selecting representative landscape photos of BukhansanDulegil 13 sections and landscape images adjectives for landscape assessment. Through the assessment, analyze landscape images of each section, landscape images factors affecting a wish to walk and landscape preferences, relationship between visitors' satisfaction and them. 'Refreshing' image was higher on the path with many trees and less artificial elements; 'urban' image was higher on the path with artificial elements. 'A wish to walk' and 'landscape preference' was higher on the path showed 'refreshing' and 'pastoral' image with many natural elements. Factors affecting 'a wish to walk' were "refreshing-unpleasant", "impressive-ordinary", factors affecting 'landscape preference' were "refreshing-unpleasant", "comfortable-uncomfortable". In addition, landscape preference was found to have a high correlation with visitors' satisfaction.

• Journal of Radiation Protection and Research
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• 제38권2호
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• pp.78-90
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• 2013

Recently, the interest on exposure to radiation is rising. The radiation exposure of mammography is higher in absorbed dose than of X-ray, therefore unnecessary exposure needs to be reduced, and higher image quality is needed. Generally, ray quality of the radiation imaging is an important factor that determines image quality and the amount of ray exposure, and they are affected by tube voltage and added filter. The X-ray energy that is exposed from mammography device is generally a continuous spectrum, which includes low energy that has minute influence on the image quality, and high energy that hinders contrast on image. Currently, molybdenum (Mo) and rhodium (Rh) are the most used added filters for mammography device, and they are used differently according to the energy region of X-ray. This study aims to find out the degree of reduction in exposure dose according to the thickness of aluminum (Al), and to study the changes in image quality and dose when the added filter plates that are made with niobium (Nb) or zirconium (Zr) are used, other than molybdenum (Mo) and rhodium (Rh), the two most used added filters that have similar atomic number and K-absorption regions as Nb and Zr. In this study, single-added filters of molybdenum (Mo), niobium (Nb), and zirconium (Zr) are used, and in some cases, Aluminum (Al) is combined with the single filters. In this case, image quality is considered to be improved depending on the type of added filters, and by using Aluminum (Al) filter together with the others, unnecessary X-ray of low energy would be absorbed, therefore the dose is expected to decrease without any influence when the concentration level becomes identical.

• Journal of Science and Technology Studies
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• 제18권2호
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• pp.135-179
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• 2018

How do robots interact with the elderly? In this paper, we analyze the contexts of interaction between robots and the elderly and the role of mediators in initiating, facilitating, and maintaining the interaction. We do not attempt to evaluate the robot's performance or measure the impact of robots on the elderly. Instead, we focus on the circumstances and contexts within which a robot is situated as it interacts with the elderly. Our premise is that the success of human-robot interaction does not depend solely on the robot's technical capability, but also on the pre-arranged settings and local contingencies at the site of interaction. We select three television shows that feature robots for the elderly and one "dementia-prevention" robot in a regional healthcare center as our sites for observing robot-elderly interaction: "Grandma's Robot"(tvN), "Co-existence Experiment''(JTBC), "Future Diary"(MBC), and the Silbot class in Suwon. By analyzing verbal and non-verbal interactions between the elderly and the robots in these programs, we point out that in most cases the robots and the elderly do not meet one-to-one; the interaction is usually mediated by an actor who is not an old person. These mediators are not temporary or secondary components in the robot-elderly interaction; they play a key role in the relationship by arranging the first meeting, triggering initial interactions, and carefully observing unfolding interactions. At critical moments, the mediators prevent the interaction from falling apart by intervening verbally or physically. Based on our observation of the robot-elderly interaction, we argue that we can better understand and evaluate the human-robot interaction in general by paying attention to the existence and role of the mediators. We suggest that researchers in human-robot interaction should expand their analytical focus from one-to-one interactions between humans and robots to human-robot-human interactions in diverse real-world situations.

• Journal of Korean Society of Forest Science
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• 제101권4호
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• pp.722-728
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• 2012

Climate change affects all biological processes in terrestrial ecosystems including photosynthesis, plant growth and productivity. This study was conducted to investigate the effects of experimental warming on the growth of Quercus variabilis seedlings. One-year-old Q. variabilis seedlings were planted in control and warmed plots in April 2010. The air temperature of warmed plots was increased by $3^{\circ}C$ compared to control plots using the infrared lamp from November 2010. Shoot height and root collar diameter were measured in March 2011 and June 2012, respectively, and aboveground and belowground biomass were also measured in March 2011 and 2012, respectively. Shoot height and root collar diameter were significantly higher in warmed plots than in control plots, except for root collar diameter in March 2011. Increment (mm) of shoot height and root collar diameter were also higher in warmed plots ($529{\pm}30$, $5.6{\pm}0.5$) than in control plots ($464{\pm}28$, $4.5{\pm}0.4$). However, there were no significant differences between warmed and control plots except for root collar diameter. Increment (g/year) of total, aboveground and belowground biomass were higher in warmed plots ($36.88{\pm}6.52$, $11.91{\pm}3.44$, $24.97{\pm}3.73$) than in control plots ($30.59{\pm}5.51$, $8.73{\pm}1.66$, $21.86{\pm}3.88$), however, the differences were not statistically significant. Higher seedling growth and biomass of warmed plots might be related to the enhanced net photosynthetic rates in spring and the extended growing season.

• Investigative Magnetic Resonance Imaging
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• 제11권1호
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• pp.27-32
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• 2007

Purpose : To evaluate the mucoid degeneration (MD) of the anterior cruciate ligament (ACL) of the knee by correlation of MRI findings with pathology, in the patients with osteoarthritis (OA). Materials and Methods : This study included 17 patients (mean 68.8 years old) who underwent preoperative MRI. In proton density-weighted sagittal and coronal images ACLs were evaluated for the thickness and signal intensity (SI). Total knee replacement arthroplasty was performed and the pathologic findings of ACL were evaluated. MD was classified as 3 grades according to the degenerated amount in microscopy. Thickness and SI was evaluated as normal or increased on MRI. Results : All of the 4 patients who showed thickened ACL showed increased SI on MRI. All of the 8 patients with increased SI of the ACL on MRI had MD in the ACL. However, remained 9 patients also had MD, in spite of their normal thickness and SI on MRI. Calcification was seen in 5 patients. Conclusion : Eight cases who showed ACL thickening or increased SI on MRI were well correlated with MD, however, because the other nine cases who showed normal thickness and normal SI of ACL on MRI also showed MD in pathology, normal MRI finding should not exclude the possibility of MD of ACL.