• Progress in Medical Physics
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• v.21 no.3
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• pp.253-260
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• 2010

Most brachytherapy treatment planning systems employ a dosimetry formalism based on the AAPM TG-43 report which does not appropriately consider tissue heterogeneity. In this study we aimed to set up a simple Monte Carlo-based intracavitary high-dose-rate brachytherapy (IC-HDRB) plan verification platform, focusing particularly on the robustness of the direct Monte Carlo dose calculation using material and density information derived from CT images. CT images of slab phantoms and a uterine cervical cancer patient were used for brachytherapy plans based on the Plato (Nucletron, Netherlands) brachytherapy planning system. Monte Carlo simulations were implemented using the parameters from the Plato system and compared with the EBT film dosimetry and conventional dose computations. EGSnrc based DOSXYZnrc code was used for Monte Carlo simulations. Each $^{192}Ir$ source of the afterloader was approximately modeled as a parallel-piped shape inside the converted CT data set whose voxel size was $2{\times}2{\times}2\;mm^3$. Bracytherapy dose calculations based on the TG-43 showed good agreement with the Monte Carlo results in a homogeneous media whose density was close to water, but there were significant errors in high-density materials. For a patient case, A and B point dose differences were less than 3%, while the mean dose discrepancy was as much as 5%. Conventional dose computation methods might underdose the targets by not accounting for the effects of high-density materials. The proposed platform was shown to be feasible and to have good dose calculation accuracy. One should be careful when confirming the plan using a conventional brachytherapy dose computation method, and moreover, an independent dose verification system as developed in this study might be helpful.

• Proceedings of the Technology Innovation Conference
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• 1997.07a
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• pp.222-223
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• 1997

By analyzing the successful innovation case of potato microtuber mass production technology, a representative case of technology-push type creative innovation in an imitation oriented research culture, this paper attempts to figure out conceptual model of creative innovation that is initiated by the public laboratories in catching-up country, Stages of creative innovation can be divided into the internal R&D stage and the external commercialization stage. Success of the internal R&D stage depended on autonomy to secure creative research idea and commitment of individual researchers. Psychological pressure evoked from sportlights of mass media and commitment of sponsor increased the intensity of research efforts of the researcher Recognition of research problem and its significance was intensified by site visits of agricultural fields, and the recognized higher impacts of expected research results and knowledge creation achieved were a fundamental source of self-motivation. In the stage of commercialization stage, various legal, socio-economic, and psychological barriers were confronted. In a catching-up country lacking of experiences of creative innovation, creative innovation process can be regarded as a barrier elimination and cultural revolution process. Among the barriers, psychological refusal of farmers to corn-sized potato seeds was critical, which finally enforced to further researches to enlarge the size of potato seeds. In addition, the researcher has concentrated his research efforts in one specialized research area by getting a series of similar research project funds rather than diversification. It was lucky for him to have a chance to carry out a series of similar researches in one research area during the last 10 years. In getting research funds from government and private companies continuously in one research area, both internal and external promoters played significant roles.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.3943-3955
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• 1975

The purposes of this study are to evaluate the utilization characteristics of electrical power consumption, to grasp the present trends in the use of electrical equipments, to estimate the demand factor and load factor being held, and to evaluate the efficiency of electical uses for the recently electrified farms cultivating paddy rice. For the purposes, 109 sample farms located in eleven villiages electrified in six different years from 1968 to 1973, were chosen at random and investigated on 35 items concerning to electrical uses and wiring systems. The survey was carried out in 1975, in the vinicity of Suweon city. The results are summarized as follows: i) The average annual power consumption on sample farms is considered to be low, being 242.9 Kwh. in 1974, and varied according to the different electrified year and size of cultivated land, respectively. It has significant positive correlation to the area of farm, too. ii) Between the number of year of electrical uses and the power consumption, there is very significant positive correlation, which could be expressed as Y=43.041+16.108 X, where X represents the number of years of electrical uses. The annual increment of power consumption is much greater at the beginning of the electrification than that at the later years, its average being approximately 20 percent. However, it is recommended that any estimation of long-term increments should be carefully investigated. iii) The monthly power consumption varies considerably throughout a year, in which the heaviest farm load occurs in November. Observing the seasonal variation of consumption, the winter-time is the heaviest season while the summer is the lowest. The result implies house lighting is chief contribution to the present electrical consumption on the farms. Comparing the variation of monthly consumption ratios between the sample farms and industries, the electrical uses on the farms are independant of the industrial uses, and further, the agricultural uses are of inverse pattern to the farms from the results that there is negative correlationship between them, iv) The number of electrical equipments used on the farms are occupied chiefly by lighting sources. Next to the lighting sources, household appliances of small quantity and some motors are used. The mean electrical quantity is about 1, 127.4 watt, which corresponds to about 37.6 per cent to the contracted quantity. The composition of quantity is chiefly occupied by the electrical motor of about 1.5 hp., single-phased. The number of the annual utilization hours of each equipment is tabulated in Table IV-5. In contradiction to the high utilization of lighting sources and small household appliances, the motor is poorly used for approximately 22 hours in a year. v) More than 55 per cent of farms want to purchase new electrical equipments such as small household appliances and electrical motors in their number. The impulse of purchasing such items is stimulated by the contacts to the mass media and their knowledge on such equipments. Consequently, the increase of electrical uses could be prompted by such trials as education and demonstration. vi) The demand and load factors on the farms vary considerably according to the greater variation of the power consumption, daily or monthly. The daily demand factor is 22.4 per cent and load factor 18.6 per cent, while the annual demand factor is 1.3 per cent and load factor 70 per cent approximately. Therefore, the low efficiency of construction cost requires re-evaluation of the present contracted quantity of 3 Kw. or increase of electrical uses. vii) The electrical energy on the farms devoted chiefly to lighten the farm residences does not contribute to the farm incomes. Consequently, the cost of electrical consumption presses considerably upon the farm economy. Therefore, there is great need to build up the electrical uses on the farms through the development of new works and techinques to utilize any electrical equipments on the production of farm products. Further more, such the development should be related to increase the actual income of the farm consumers.

• Ocean and Polar Research
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• v.37 no.1
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• pp.49-59
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• 2015

Spatial variation in the reproductive effort of Manila clam Ruditapes philippinarum is often closely associated with variation in the seawater temperature and food availability, which determines gonad maturity and the quantity of gamates produced during spawning. Previous studies also have reported that severe infection by the protozoan parasite Perkinsus olseni exerts a negative impact on clam reproduction, retarding gonad maturation or decreasing the reproductive effort. In the present study, we investigated impacts of P. olseni infection on the reproductive condition of Manila clam during a spawning season. Histology revealed that 54% of female clams in Wando off the south coast were in spawning, while only 10% of the female from Gomso and 0% of the female from Seonjaedo in Gyeonggi bay off the west coast were engaged in spawning at the end of May in 2004. Ray's fluid thioglycollate media (RFTM) assay was applied to assess P. olseni infection and indicated that the infection intensity in Wando ($3,608,000{\pm}258,000cells/g$ wet tissue) was significantly higher than the levels in Gomso ($1,305,000{\pm}106,000cells/g$ wet tissue) and Seonjaedo ($1,083,000{\pm}137,000cells/g$ wet tissue, p < 0.001). The size of the ripe female follicle determined from histology was significantly smaller in Wando ($0.032mm^2$) compared to the sizes in Gomso ($0.059mm^2$) and Seonjaedo ($0.052mm^2$, p < 0.05). Accordingly, the number of ripe eggs in the follicle was significantly fewer among clams in Wando (14) compared to the numbers determined in Gomso (23) and Seonjaedo (22). The absolute quantity of egg in ripe clams from Wando (31.01 mg) was also significantly smaller than Seonjaedo (61.79 mg) and Gomso (133.3 mg). Quantity of total protein, carbohydrate, and lipid in the tissue in the Wando samples was significantly smaller than the quantities determined in Gomso and Seonjaedo (p < 0.001). The observed poor reproductive condition and proximate tissue composition of the females in Wando were, in part, explained by the extremely high level of the parasites, sapping the ability to store energy in the host tissues, which is used in tissue growth and the egg production.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.303-309
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• 1999

Mass mortality of the Manila clam, Ruditapes philippinarum has been reported all along the west and south coast of Korea for the past several years. As a pathogenic agent, Perkinsus sp., an endoparasitic protozoan has been identified in this study and believed to be responsible for the mass mortalities. Prevalence and infection intensity of Perkinsus sp. was investigated from a Manila clam population inhabiting at Komsoe Bay in the west coast where mass mortality of the clam has been reported. A total of 142 Manila clam, 50 oyster, Crassostrea gigas, 10 ark shell, Scapharca broughtonii, and 5 predatory gastropada, Rapana venosa were examined for the presence and the quantity of Perkinsus sp. Ray's fluid thioglycollate medium method (FTM method) with modified Mackin's infection intensity scale and Choi's quantitative method were used in detecting and quantifying the parasite. All individuals of R. philippinarum examined in this study were infected with Perkinsus sp., indicating $100\%$ prevalence while none of the oysters and the gastropods exhibited the parasite. Six to ten individual hypnospores of Perkinsus sp. were counted from the ark shells. The number of hypnospores in the clam tissues varied from 16,667 to 4,091,667, with a mean number of 1,077,628. Average infection intensity according to Mackin's was 2.87, indicating a moderate infection. A negative correlation was observed between the number of Perkinsus sp. in the tissue and the condition index, a ratio tissue wet weight to shell cavity volume. The clam size and the infection intensity in terms of total number of parasites were positively correlated; the bigger clam, the heavier infection. Such high number of Perkinsus sp. counted in the clams could be enough to cause physiological disturbance of clams, such as retarded growth and reproduction. It is also believed that such a high infection leads mortality of the clam via continuous draining of the energy by metabolic activities and reproduction of the parasites. Correlation between the condition index and the infection intensity observed in this study supports this hypothesis.

• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.131-142
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• 2011

In recent years, Social Network Service, which is defined as a web-based service that allows an individual to construct a public or a semi-public profile within a bounded system, articulates a list of other users with whom they share connections, and traverses their list of connections. For example, Facebook and Twitter are the representative sites of Social Network Service, and these sites are the big issue in the world. A lot of people use Social Network Services to connect and maintain social relationship. Recently the users of Social Network Services have increased dramatically. Accordingly, many organizations become interested in Social Network Services as means of marketing, media, communication with their customers, and so on, because social network services can offer a variety of benefits to organizations such as companies and associations. In other words, organizations can use Social Network Services to respond rapidly to various user's behaviors because Social Network Services can make it possible to communicate between the users more easily and faster. And marketing cost of the Social Network Service is lower than that of existing tools such as broadcasts, news papers, and direct mails. In addition, Social network Services are growing in market place. So, the organizations such as companies and associations can acquire potential customers for the future. However, organizations uniformly communicate with users through Social Network Service without consideration of the characteristics of the networks although networks have different effects on information deliveries. For example, members' cohesion in an offline communication is higher than that in an online communication because the members of the offline communication are very close. that is, the network of the offline communication has a strong tie. Accordingly, information delivery is fast in the network of the offline communication. In this study, we compose two networks which have different characteristic of communication in Twitter. First network is constructed with data based on an offline communication such as friend, family, senior and junior in school. Second network is constructed with randomly selected data from users who want to associate with friends in online. Each network size is 250 people who divide with three groups. The first group is an ego which means a person in the center of the network. The second group is the ego's followers. The last group is composed of the ego's follower's followers. We compare the networks through social network analysis and follower's reaction analysis. We investigate density and centrality to analyze the characteristic of each network. And we analyze the follower's reactions such as replies and retweets to find differences of information delivery in each network. Our experiment results indicate that density and centrality of the offline communicationbased network are higher than those of the online-based network. Also the number of replies are larger than that of retweets in the offline communication-based network. On the other hand, the number of retweets are larger than that of replies in the online based network. We identified that the effect of information delivery in the offline communication-based network was different from those in the online communication-based network through experiments. So, you configure the appropriate network types considering the characteristics of the network if you want to use social network as an effective marketing tool.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5C
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• pp.664-672
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• 2004

Widespread popularity of wireless data communication devices, coupled with the availability of higher bandwidths, has led to an increased user demand for content-rich media such as images and videos. Since such content often tends to be private, sensitive, or paid for, there exists a requirement for securing such communication. However, solutions that rely only on traditional compute-intensive security mechanisms are unsuitable for resource-constrained wireless and embedded devices. In this paper, we propose a selective partial image encryption scheme for image data hiding , which enables highly efficient secure communication of image data to and from resource constrained wireless devices. The encryption scheme is invoked during the image compression process, with the encryption being performed between the quantizer and the entropy coder stages. Three data selection schemes are proposed： subband selection, data bit selection and random selection. We show that these schemes make secure communication of images feasible for constrained embed-ded devices. In addition we demonstrate how these schemes can be dynamically configured to trade-off the amount of ded devices. In addition we demonstrate how these schemes can be dynamically configured to trade-off the amount of data hiding achieved with the computation requirements imposed on the wireless devices. Experiments conducted on over 500 test images reveal that, by using our techniques, the fraction of data to be encrypted with our scheme varies between 0.0244％ and 0.39％ of the original image size. The peak signal to noise ratios (PSNR) of the encrypted image were observed to vary between about 9.5㏈ to 7.5㏈. In addition, visual test indicate that our schemes are capable of providing a high degree of data hiding with much lower computational costs.

• Information Systems Review
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• v.18 no.1
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• pp.57-78
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• 2016

Hacking has raised many critical issues in the modern world, particularly because the size and cost of the damages caused by this disruptive activity have steadily increased. Accordingly, many significant studies have been conducted by behavioral scientists to understand hackers and their practices. Nonetheless, only qualitative methods, such as interviews, meta-studies, and media studies, have been employed in such studies because of hacker sampling limitations. Existing studies have determined that intrinsic motivation was the dominant factor influencing hackers, and that their techniques were mainly acquired from online hacking communities. However, such results have yet to be causally proven. This study attempted to identify the causal factors influencing the motivational and environmental factors encouraging hackers to learn hacking skills. To this end, hacker community members using the theory of planned behavior were observed to identify the causal factors of their learning of hacking skills. We selected a group of students who were developing their hacking skills. The survey was conducted over a two-week period in May 2015 with a total of 227 students as respondents. After list-wise deletion, 215 of the responses were deemed usable (94.7 percent). In summary, the hackers were aware that hacking skills are considered socially unethical, and their attitudes toward the learning of hacking skills were affected by both intrinsic and extrinsic motivations. In addition, the characteristics of the online hacking community affected their perceived behavioral control. This study introduced new concepts in the process of conducting a causal relationship analysis on a hacker sample. Moreover, this research expanded the discussion on the causal direction of subjective norms in unethical research, and empirically confirmed that both intrinsic and extrinsic motivations affect the learning of hacking skills. This study also made a practical contribution by raising the educational and policy response issues for ethical hackers and demonstrating the necessity to intensify the punishment for hacking.

• Investigative Magnetic Resonance Imaging
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• v.9 no.2
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• pp.109-116
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• 2005

Purpose : To determine the usefulness of additional Mn-DPDP MRI for preoperative evaluation of the patients with colorectal cancers by comparison of dual-phase CT scan, Mn-DPDP enhanced MRI and combination of CT and MRI. Materials and Methods : Fifty-three colorectal cancer patients with 92 metastatic nodules underwent dualphase (arterial and portal) helical CT scan and Mn-DPDP MRI prior to surgery. The indication of MRI was presence or suspected of having metastatic lesions at CT scan and/or increased serum carcinoembryonic antigen (CEA) levels (10 ng/mL or more). The diagnosis was established by the combination of findings at surgery, intraoperative ultrasonography, and histopathologic examination. Two radiologists interpreted CT, MRI, and combination of CT-MRI at discrete sessions and evaluated each lesion for location, size, and intrinsic characteristics. The lesions were divided into three groups according to their diameter; 1cm<, 1-2 cm, and >2 cm. Diagnostic accuracy was evaluated using the alternative-free response receiver operating characteristic method. Detection and false positive rate were also evaluated. Results : In the lesions smaller than 1 cm, detection rate of combined CT-MRI was superior to CT or MRI alone (82%, p=0.036). The mean accuracy (Az values) of combined CT and MRI was significantly higher than that of CT in the lesions smaller than 2 cm (1 cm<, p=0.034; 1-2 cm, p=0.045). However, there was no significant difference between MRI and combined CT-MRI. The false positive rate of CT was higher than those of combined CT-MR in the lesions smaller than 1 cm (28%, p=0.023). Conclusion : Additional MRI using Mn-DPDP besides routine CT scan was helpful in differentiating the hepatic lesions (<2 cm) and could improve detection of the small hepatic metastases (<1 cm) from colorectal carcinoma.

• Journal of Animal Environmental Science
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• v.8 no.1
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• pp.9-16
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• 2002

This study was conducted to develope the new solid separating system which can be efficiently and economically removed the solid parts in high pollutants concentration of pig slurry. The pollutants concentration, BOD$_{5}$ , COD and SS of the slurry used in this study was 15,990($\pm$2,389)mg/l, 20,004($\pm$5,512)mg/l and 26,486($\pm$5,935)mg/l, respectively. After removal of solid part in slurry, the pollutants concentration, BOD$_{5}$, COD and SS was change into 5,617($\pm$690)mg/l, 5,553($\pm$633)mg/land 1,456($\pm$341)mg/l, respectively in the Fixed biological membrane tank. The reduction of the pollutants concentration of suspend liquid through membrane will be allowed to greatly improve the water purification by an Activated sludge method. This separating system consisted of a temporary storage, a circulating tank and a Fixed Biological membrane tank. A temporary storage which has a draining system of screw type and an aeration device played a tremendous role in draining the solid by filled an aeration of 0.3 l/min. A Fixed Biological membrane tank of which a styrofoam filled in a 2/3 volume as a Biological media was fixed by a stainless steel net (pore size : 0.5mm) to separate the liquid layer of influx in them. The separating system efficiency factors were the speed of screw motor, cycle number of slurries in a circulating tank and moisture contents of solid effluent through the screw path. Although the pollutants concentration was very variable in temporary storage, the final concentration of $BOD_5$ and SS, except COD of the suspended liquid in a Fixed biological membrane were not different regardless of cycle number of a circulating tank. Moisture contents of effluent from temporary storage was 73% under the speed 1 ppm of screw motor and 62% under the 1/4rpm of it.