• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1515-1527
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• 2016

With the growth of big data, machine learning, and cloud computing, the importance of storage that can store large amounts of unstructured data is growing recently. So the commodity hardware based distributed file systems such as MAHA-FS, GlusterFS, and Ceph file system have received a lot of attention because of their scale-out and low-cost property. For the data fault tolerance, most of these file systems uses replication in the beginning. But as storage size is growing to tens or hundreds of petabytes, the low space efficiency of the replication has been considered as a problem. This paper applied erasure coding data fault tolerance policy to MAHA-FS for high space efficiency and introduces VDelta technique to solve data consistency problem. In this paper, we compares the performance of two file systems, MAHA-FS and GlusterFS. They have different IO processing architecture, the former is server centric and the latter is client centric architecture. We found the erasure coding performance of MAHA-FS is better than GlusterFS.

• Tuberculosis and Respiratory Diseases
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• v.43 no.4
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• pp.623-629
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• 1996

Bronchial carcinoid tumors are uncommon, constituting approximately 5% of all primary lung cancers. Carcinoid tumors belong to the calss of neuroendocrine tumors that consist of cells that can store and secrete neuramines and neuropeptides. Neuroendocrine tumors of the lung include three pathologic types : a low-grade malignancy, the so-called 'typical carcinoid', a more aggressive tumor, the "atypical carcinoid", and the most aggressive malignant neoplasm, the small-cell carcinoma. Atypical carcinoid tumor have a higher malignant potential, is more commonly peripheral than is the typical carcinoid tumor. Histologic features would characterize a carcinoid as hitologically atypical : increased mitotic activity, pleomorphism and irregularity of neuclei with promonent nucleoli, hyperchromatin, and abnormal nuclear-cytoplasmic ratio, areas of increased cellularity with disorganization of architecture, and areas of tumor necrosis. Metastatic involvement of regional lymph nodes and distant organ is common. The prognosis is related to size of the tumor, typical of atypical appearance, endoluminal of extraluminal growth, vascular invasion, node metastasis, Pulmonary resection is the treatement of choice for bronchial carcinoid. We experienced one case of bronchopulmonary atypical carcinoid tumor. In the case, radiologic study showed solitary lung mass with liver metastasis and the level of 5-HIAA was elevated. There was no history of cutaneous flushing, diarrhea, valvular heart disease. The authors reported a case of bronchopulmonary atypical carcinoid tumor with review of literatures.

• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.133-142
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• 2009

Recently, with the advance of wireless internet and the frequent use of mobile devices, demand for LBS(Location Based Service) is increasing, and research is required on spatial indexes for the storage and maintenance of spatial data to provide efficient LBS in mobile device environments. In addition, the use of flash memory as an auxiliary storage device is increasing in order to store large spatial data in a mobile terminal with small storage space. However, the application of existing spatial indexes to flash-memory lowers index performance due to the frequent updates of nodes. To solve this problem, research is being conducted on flash-memory based spatial indexes, but the efficiency of such spatial indexes is lowered by low utilization of buffer and flash-memory space. Accordingly, in order to solve problems in existing flash-memory based spatial indexes, this paper proposed FR-Tree (Flash-Memory based R-Tree) that uses the node compression technique and the delayed write operation technique. The node compression technique of FR-Tree increased the utilization of flash-memory space by compressing MBR(Minimum Bounding Rectangle) of spatial data using relative coordinates and MBR size. And, the delayed write operation technique reduced the number of write operations in flash memory by storing spatial data in the buffer temporarily and reflecting them in flash memory at once instead of reflecting the insert, update and delete of spatial data in flash-memory for each operation. Especially, the utilization of buffer space was enhanced by preventing the redundant storage of the same spatial data in the buffer. Finally, we perform ed various performance evaluations and proved the superiority of FR-Tree to the existing spatial indexes.

• Journal of Korea Multimedia Society
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• v.8 no.4
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• pp.439-449
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• 2005

Distributed main memory database management systems (DMM-DBMSs) store the database in main memories of the participating sites. They provide high performance through fast access to the local databases and high speed communication among the sites. Recently, a lot of research results on DMM- DBMSs has been reported. However, to the best of our knowledge, there is no known research result on the performance of the catalog management schemes for DMM-DBMSs. In this work, we evaluated the performance of the partitioned catalog management schemes through experimental analysis. First, we classified the partitioned catalog management schemes into three categories : Partitioned Catalogs Without Caching (PCWC), Partitioned Catalogs With Incremental Caching (PCWIC), and Partitioned Catalogs With Full Caching (PCWFC). Experiments were conducted by varying the number of sites, the number of terminals per site, buffer size, write query ratio, and local query ratio. Experiments show that PCWFC outperforms the other two schemes in all cases. It also means that the performance of PCWIC gradually increases as time goes by. It should be noted that PCWFC does not guarantee high performance for disk-based distributed DBMSs in cases when the workload of individual site is high, catalog write ratio is high, or remote data objects are accessed very frequently. Main reason that PCWFC outperforms for DMM-DBMSs is that query compilation and remote catalog access can be done in a very high speed, even when the catalogs of the remote data objects are frequently updated.

• Journal of KIISE
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• v.43 no.3
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• pp.304-313
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• 2016

We present a novel memory-efficient parallel ray casting algorithm for unstructured grid volume rendering on multi-core CPUs. Our method is based on the Bunyk ray casting algorithm. To solve the high memory overhead problem of the Bunyk algorithm, we allocate a fixed size local buffer for each thread and the local buffers contain information of recently visited faces. The stored information is used by other rays or replaced by other face's information. To improve the utilization of local buffers, we propose an image-plane based ray grouping algorithm that makes ray groups have high coherency. The ray groups are then distributed to computing threads and each thread processes the given groups independently. We also propose a novel hash function that uses the index of faces as keys for calculating the buffer index each face will use to store the information. To see the benefits of our method, we applied it to three unstructured grid datasets with different sizes and measured the performance. We found that our method requires just 6% of the memory space compared with the Bunyk algorithm for storing face information. Also it shows compatible performance with the Bunyk algorithm even though it uses less memory. In addition, our method achieves up to 22% higher performance for a large-scale unstructured grid dataset with less memory than Bunyk algorithm. These results show the robustness and efficiency of our method and it demonstrates that our method is suitable to volume rendering for a large-scale unstructured grid dataset.

• The Journal of the Korea Contents Association
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• v.20 no.9
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• pp.549-557
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• 2020

Recently, the number of coffee shops has continued to increase, and information searches have been increasing for consumers who want to visit coffee shops. We wanted to find out the impact on the intention of revisiting a coffee shop by adding information search factors to the existing coffee shop's selection properties and search for the actual selection properties, and summarize the results as follows. The analysis of this study was conducted in two ways, before and after visiting a coffee shop through information search. First, the four factors and optional attributes that are important in information retrieval were the reliability of information (the number of reviews and views by coffee shops, recent postings), physical environment (the proximity of stores, the atmosphere, size, presence of side menus), visuality of information (physical environment, background, design, easy composition), merchantability (the taste of coffee, convenience of parking). In addition, the selection properties for satisfaction after visiting coffee shops through information search were derived from five general characteristics of coffee shops, menu, information consistency, taste of coffee, and convenience of parking, and among them, the consistency of information, taste of coffee, and general characteristics of coffee were found to affect the intention of revisiting again.

• Journal of Aerospace System Engineering
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• v.14 no.1
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• pp.68-73
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• 2020

This purpose of this paper was to review the development trend of the VTOL MAVs with a ducted propellant that can fly like the VTOL at intermediate and high speeds, hovering, landing, and lifting off vertically over urban areas, warships, bridges, and mountainous terrains. The MAV differs in flight characteristics from helicopters and fixed wings in many respects. In addition to enhancing thrust, the duct protects personnel from accidental contact with the spinning rotor. The purpose of the U.S. Army FCS and DARPA's OAV program is spurring development of a the VTOL ducted MAV. Today's MAVs are equipped with video/infrared cameras to hover-and-stare at enemies hidden behind forests and hills for approximately one hour surveillance and reconnaissance. Class-I is a VTOL ducted MAV developed in size and weight that individual soldiers can store in their backpacks. Class-II is the development of an organic VTOL ducted fan MAV with twice the operating time and a wider range of flight than Class-I. MAVs will need to develop to perch-and-stare technology for lengthy operation on the current hover-and-stare. The near future OAV's concept is to expand its mission capability and efficiency with a joint operation that automatically lifts-off, lands, refuels, and recharges on the vehicle's landing pad while the manned-unmanned ground vehicle is in operation. A ducted MAV needs the development of highly accurate relative position technology using low cost and small GPS for automatic lift-off and landing on the landing pad. There is also a need to develop a common command and control architecture that enables the cooperative operation of organisms between a VTOL ducted MAV and a manned-unmanned ground vehicle.

• Journal of Korean Public Health Nursing
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• v.12 no.2
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• pp.185-200
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• 1998

It has been contributed to public health that the hospital has multiplied in the aspect of number and has been a large size with development of modern medical science, meanwhile the problem of hospital infection is coming out seriously. Respiratory hospital infection among hospital infections develops, very commonly from patients having taken the operation of intubation or tracheostomy, which results from a big factor that the infection developed from medical appliances used for respiration aids, contamination of solution and infection of medical staff. This study is separated into four steps-the time to use normal saline and distillation water for storaging catheter which are the cause of the infection of solution to store distillation water and catheter, not to say the catheter used when the patient who should get tracheostomy operation takes suction. The purpose of this study is to offer the basic data which are needed to check contamination degree as time goes by and nurse intervention and grope for a new nursing intervention. The target of this study is hospitalized 1D an intensive care unit having 700 sickbeds which is located in IKSAN city and it targeted patients before 7 days passed after an operaion of a tracheostormy. Materials collected were analyzed by SPSS PC+ figures program. The result of this study were as follows ; 1. The gradual contamination levels of the normal saline used In suction are showing that colony increase in proportion to the length of time. 2. while colony increases in normal saline with the lapse of time. distillation water mixed with 5cc of potadine did not show any sign of the formation of colony from its preparation until it was used for 8 hours. 3. Such variables as the period of intubation insertion. the length of hospitalization in I.C.U. the age and the level of contamination of normal saline have no inter-relationship. Therefore. as the length of normal saline used In suction. the contamination level increases with the excelleration of the contamination speed. 4. Regarding the number of suction and the contamination level of the normal saline. We can observe correlation contamination level in the 3 step of suction(mean value:13.4) and the saline which was used for one hours(r=0.702. P=0.00l). four hours(r=0.694. P=0.00l). eight hours(r=0.488. P=0.029). Further we can observe contamination in the 4 step of suction (mean value: 17 .8) well as saline used for eight hours; [for one hours (r=0.64l. P=0.002). four hours (r=0.670. P=0.00l). eight hours (r=0.57 4. P=0.008)]. Thesedays clinics use normal saline by changing it. three times a day. however. the timing of saline change and the current suction methoed should be changed given the one hour used normal saline contamination number 79.850. Regarding the number of suction and the contamination lend of the normal saline.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.1
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• pp.97-107
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• 2002

In this paper, we propose the realization of on-line handwritten Chinese character recognition for mobile personal digital assistants (PDA). We focus on the development of an algorithm having a high recognition performance under the restriction that PDA requires small memory storage and less computational complexity in comparison with PC. Therefore, we use index matching method having computational advantage for fast recognition and we suggest a unit reconstruction method to minimize the memory size to store the character models and to accomodate the various changes in stroke order and stroke number of each person in handwriting Chinese characters. We set up standard model consisting of 1800 characters using a set of pre-defined units. Input data are measured by similarity among candidate characters selected on the basis of stroke numbers and region features after preprocessing and feature extracting. We consider 1800 Chinese characters adopted in the middle and high school in Korea. We take character sets of five person, written in printed style, irrespective of stroke ordering and stroke numbers. As experimental results, we obtained an average recognition time of 0.16 second per character and the successful recognition rate of 94.3% with MIPS R4000 CPU in PDA.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.5
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• pp.391-401
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• 2009

The hybrid approach for structural experiments decomposes a structure into independent substructures that can be tested or simulated. The results from the decomposed substructures are combined to predict the behaviors of the entires structure. The hybrid approach is especially useful for the hybrid pseudo-dynamic tests that overcome the limitations of size of a test structure present in a shaking table test. The development of a computer system for the hybrid experiment requires a data model that formally organizes the information involved in the hybrid experiments. This paper provides the data model for representing the information involved in the hybrid experiments, by modifying the classes and attributes for the hybrid experiments in the Lehigh Model that is one of the data models for structural experiments. The data model for the hybrid experiments includes the classes for the physical substructures being tested and the analytical substructures being analyzed, and the simulation coordinator managing the overall experiments. Some objects for classes are implemented as an example to show the links among the classes. The data model presented in this paper can be applied for developing a computer system that helps structural engineers and researchers store, share, and access the information for the hybrid experiments.