• Tribology and Lubricants
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• v.22 no.4
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• pp.211-217
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• 2006

Ring and groove wear may not be a problem in most current automotive engines. However, a small change in ring face and groove geometry can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blow-by and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each part's wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of rings and grooves are obtained from three engines before and after engine durability test. The calculated wear data of each part are turn out to be at the lower bound of aver-aged test values or a little below.

• Tribology and Lubricants
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• v.35 no.6
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• pp.376-381
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• 2019

Surface texturing is widely applied to reduce friction and improve the reliability of machine elements. Despite extensive theoretical studies to date, most research has been limited to parallel thrust bearings, mechanical face seals, piston rings, etc. However, most sliding bearings have a convergent film shape in the sliding direction and the hydrodynamic pressure is mainly generated by the wedge action. The results of surface texturing on inclined slider bearings are largely insufficient. This paper is the first part of a recent study focusing on the effect of the groove position on the lubrication performances of inclined slider bearings. We model a slider bearing with one rectangular groove on a fixed pad and analyze the continuity and Navier-Stokes equations using a commercial computational fluid dynamics (CFD) code, FLUENT. The results show that the film convergence ratio and the groove position have a significant influence on the pressure and velocity distributions. There are groove positions to maximize the supporting load with the film convergence ratio and the groove reduces the frictional force acting on the slider. Therefore, the proper groove position not only improves the load-carrying capacity of the slider bearings but also reduces its frictional loss. The present results apply to various surface-textured sliding bearings and can lead to further studies.

• Tribology and Lubricants
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• v.35 no.6
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• pp.382-388
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• 2019

It is currently well known that surface textures act as lubricant reservoirs, entrap wear debris, and hydrodynamic bearings, which can lead to certain increases in load-carrying capacities. Until recently, the vast majority of research has focused on parallel sliding machine components such as thrust bearings, mechanical face seals, piston rings, etc. However, most sliding bearings have a convergent film shape in the sliding direction and their hydrodynamic pressure is mainly generated by the wedge action. Following the first part of the present study that investigates the effect of groove position on the lubrication performances of inclined slider bearings, this paper focuses on the effects of groove depths and film thicknesses. Using a commercial computational fluid dynamics (CFD) code, FLUENT, the continuity and Navier-Stokes equations are numerically analyzed. The results show that the film thickness and groove depth have a significant influence on the pressure distribution. The maximum pressure occurs at the groove depth where the vortex is found and, as the depth increases, the pressure decreases. There is also a groove depth to maximize the supporting load with the film thickness. The friction force acting on the slider decreases with deeper grooves. Therefore, properly designed groove depths, depending on the operating conditions, can improve the load-carrying capacity of inclined slider bearings as compared to the bearings without a groove.

• Journal of Chest Surgery
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• v.25 no.3
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• pp.220-231
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• 1992

We have performed 28 single lung transplantation in mongrel dogs transplanting the left lung exclusively from November 1989 to September 1991, in the department of thoracic surgery of Seoul National University Hospital. In the donor dogs, the main pulmonary artery was divided proximal to its bifurcation, and the left atrium was incised freeing the left veins with a generous atrial cuff. We used cold saline in the first 7 transplantations and Euro-Collins or modified Euro-Collins solution in the remaining 17 transplantations as a lung preservatives. The bronchus was divided at two cartilage rings proximal to the upper lobe bronchus take off. In the recipient procedure, we used a Fogarty catheter as a bronchus block. Left atrial anastomosis was performed first using 5-O prolene and the pulmonary artery was anastomosed using 6-O prolene. The bronchus was anastomosed next with 4-O vicryl interruptedly and covered with a greater omentum which had been prepared previously. All dogs received cyclosporin A and azathioprine as immunosuppressants and were divided into two group. In the 10 Group I dogs, they survived within 6 days, mean survival time was 66.8$\pm$53.4 hours. In remainder 14 Group lI dogs, they survived above 6 days, mean survival time was 9. 5$\pm$5.6 days. The cause of death were as follows: 2 cases of sacrifice, 2 cases of respiratory insufficiency during operation, 2 cases of arrhythmia immediate postoperatively, 2 cases of bleeding, others in Group I, and 6 cases of sacrifice, 4 cases of sepsis, 3 cases of bleeding, others in Group lI. Results of bronchoscopic findings were obstruction above 50% in 12 cases of 16 performance cases within 5th day. Early chest radiologic haziness were showed, and total lung perfusion defect was frequently showed in both group within 7th day. Main autopsy findings were left atrial and pulmonary arterial thrombi and bronchial obstruction The major histologic findings of Group I were pleural exudate, hemorrhagic infarct, pulmonary congestion, and interesting histologic findings of Group II were 3 cases of perivascular or peribronchial lymphocyte infiltration, 3 cases of hemorrhage infarct, 2 cases of interstitial pneumonitis. The structual change of bronchioles, suggesting bronchiolitis obliterans was not observed due to improper preparation of proximal pulmonary tissue and short term survival times.

• Journal of Crop Science and Biotechnology
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• v.11 no.1
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• pp.45-50
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• 2008

Lignans and neolignans are optically active plant secondary metabolites. Research on biosynthesis of lignans has already been advanced especially for the formation of (+) pinoresinol but information on the biosynthesis of 8-O-4'- neolignans is still limited. Moreover, the chemical structure(position of substituents on aromatic rings) and stereochemistry of 8-O-4' neolignans is not clear. Katayama and Kado discovered that incubation of cell-free extracts from E. ulmoides with coniferyl alcohol in the presence of hydrogen peroxide gave (+)-erythro- and (-)-threo- guaiacylglycerol 8-O-4'-(coniferyl alcohol) ether (GGCE)(diastereomeric ratio, 3:2) which is the first report on enzymatic formation of optically active -8-O-4' neolignans from an achiral monolignol. In this aspect, enzymatic formation of guaiacyl 8-O-4' neolignan is noteworthy to clarify its stereochemistry from incubation of coniferyl alcohol with enzyme prepared from Eucommia ulmoides. In this experiment, soluble and insoluble enzymes prepared from E. ulmoides were incubated with 30 mM coniferyl alcohol(CA) for 60 min. The enzyme catalyzed GGCE, dehydrodiconiferyl alcohol(DHCA), and pinoresinol identified by reversed phase HPLC. Consequently, diastereomeric compositions of GGCE were determined as erythro and threo isomer. Enantiomeric composition was determined by the chiral column HPLC. Both enzyme preparations enantioselectively formed (-)-erythro, (+)-erythro and (+)-threo, (-)-threo-GGCEs respectively.

• Korean Management Science Review
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• v.27 no.2
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• pp.81-95
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• 2010

There is an increasing interest in contents such as movie, drama and game using transmedia storytelling. It includes Le Grand Chef, The War of Flower, Dae Jang Geum, The Matrix, Harry Potter and The Lord of the Rings. However, transmedia contents have not always been successful. To study the factors affecting possible outcomes of transmedia storytelling, we analyzed the intention on transmedia of potential consumers who have not been exposed to transmedia contents before. To this end, we investigated two different cases : first, potential customer intention to watch dramas which will be produced after launching comic-based movies; second, potential customer intention to see movies which will be made after broadcasting comic-based TV dramas. In each case, we analyzed the outcomes from potential customers by applying several variables including gender, exposure to the original and components of contents (plot, quality of act and music etc). Our study showed that potential customers prefer movies or TV dramas with quality of acting, directing, casting and storylines. Interestingly, the quality of acting is more important in dramas than in movies and casting is an appealing factor to potential customers in movies. In TV drama cases, potential customers have high watching intentions when they read the original content. Among them, male potential customer have low watching intentions on TV drama when they did not read the original content. However, female potential customers have high watching intentions on TV drama regardless of the previous exposure to the originals. In movie cases, female potential customers have higher intentions on seeing movies than male. These results suggest that one needs to consider several factors such as casting, acting and gender for generating transmedia contents with a high probability of success.

• Journal of Microbiology and Biotechnology
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• v.19 no.5
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• pp.439-446
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• 2009

The biosynthesis study of antibiotics saframycin (SFM) in Streptomyces lavendulae and safracin (SAC) in Pseudomonas fluorescens demonstrated that 3-hydroxy-S-methyl-O-methyltyrosine (3hSmOmTyr), a nonproteinogenic amino acid, is the precursor of the tetrahydroisoquinoline molecular core. In the biosynthetic gene cluster of SAC/SFM, sacD/sfmD encodes a protein with high homology to each other but no sequence similarity to other known enzymes; sacF/sfmM2 and sacG/sfmM3 encode methyltransferases for C-methylation and O-methylation; and sacE/sfinF encodes a small protein with significant sequence similarity to the MbtH-like proteins, which are frequently found in the biosynthetic pathways of non ribosomal peptide antibiotics and siderophores. To address their function, the biosynthetic cassette of 3h5mOmTyr was heterologously expressed in S. coelicolor and P. putida, and an in-frame deletion and complementation in trans were carried out. The results revealed that (i) SfmD catalyzes the hydroxylation of aromatic rings; (ii) sacD/sacF/sacG in the SAC gene cluster and sfmD/sfmM2/sfmM3 in the SFM cluster are sufficient for the biosynthesis of 3h5mOmTyr; and (iii) the mbtH-like gene is not required for the biosynthesis of the 3h5mOmTyr precursor.

• Journal of Biosystems Engineering
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• v.28 no.5
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• pp.403-410
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• 2003

To enhance the performance of a rice seed pelleting machine and the quality of rice-seed pellets made, improvement of the rice seed pelleting machine developed previously(Park, 2002) was tried and its performance was evaluated. As compared with the previous pelleting machine, a feeding mechanism of pellet materials to the forming rolls was changed from screw conveyor to hydraulic cylinder for proper feeding, rings were installed among rows of semi-spherical forming grooves on the forming rolls for reducing pellet materials loss and seeds damage, and discharging air nozzles were added for complete discharging of the pellets made. Through performance tests, capacity, pelleting ratio, and seed loss ratio of the pelleting machine were investigated at the mixing ratios of soil to rice seed of 6 : 1, 7 : 1, and 8 : 1, and rotating speeds of the forming rolls of 7 rpm, 10 rpm, and 13 rpm. As results of performance evaluation, pelleting ratios were in the range of 77 ∼ 89 ％, and maximum pelleting ratio increased by 18 % in comparison with that of the previous machine. Maximum capacity was about 110 kg/h(about 63,000 pellets/h), which was increased by 70 % in comparison with that of the previous machine. But, ratios of seed loss were in the range of 24 - 49 ％, which were not improved.

• Archives of design research
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• v.18 no.1 s.59
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• pp.157-166
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• 2005

The purpose of the study is to understand the symbolic meaning of jewelry. Among various characteristics of symbols, the symbolic meaning represents the correlation between meanings. Wearing jewelry is an instinctive action that can be witnessed from ancient civilizations. Man used jewelry for various purposes, as an ornament, an amulet, a symbol of wealth or power or as a token of love. In this study, I have researched the symbolic meaning of jewelry in its historic background focusing on rings that show the strongest symbolic characteristic among jewelries. Whereas the symbolic meaning of jewelry was strongly accentuated in the ancient and medieval times, it was gradually weakened in the modern time. Also, while jewelry in the ancient and medieval times showed commonness and universality, jewelry in modern time expressed individuality. Although the meaning of jewelry changed progressively by interacting with the external environment, jewelry has always roused sense and symbolism from our hearts and has acted as a means to express ideas and emotions of human beings.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.15 no.2
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• pp.83-94
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• 1979

It is more than half a century since anchovy boat seine has been introduced in Korean fishery to catch anchovies, but the study on it was began in 1970's by the authors. In 1971, the authors carried out an experiment about the net formation of the traditional gear in tow by using model net, and in 1978, about the patti net gear, commercially used in Japan. Now, the authors investigated the new model net, model 79, expecting to be suitable for commercial fishery in Korea, with the strong point of those two gears kept and the weak point of them corrected. The experimental gear was constructed attached the long net pendants to the fore end of extension wing by shortening its length in two-third of the traditional gear. Inside wing was improved so as to show high opening in tow. Rubber bobbins and hanging rings are used to prevent the heavy friction of bosom ground rope against the sea bed. The gear was used to catch anchovies in the commercial fishing ground in the south-eastern coastal waters of Korea, from May to October in 1979. From the experiment, the following results are found. 1. In opening height, the experimented gear was 30 percent greater than the traditional one. 2. It took 3 to 5 minutes for the bosom ground rope to sink from the surface to the sea bed, while 10 to 15 minutes for the traditional gear to do. 3. Ground rope never scooped mud, even in the muddy sea bed. 4. The gear showed better catchability than the traditional gear.