• Journal of Korea Multimedia Society
• /
• v.12 no.12
• /
• pp.1710-1717
• /
• 2009

Flash memory has become the most important storage media in mobile devices along with its attractive features such as low power consumption, small size, light weight, and shock resistance. However, a flash memory can not be written before erased because of its erase-before-write characteristic, which lead to some garbage collection when there is not enough space to use. In this paper, we propose a novel garbage collection scheme, called block-level buffer garbage collection. When it is need to do merge operation during garbage collection, the proposed scheme does not merge the data block and corresponding log block but also search the block-level buffer to find the corresponding block which will be written to flash memory in the next future, and then decide whether merge it in advance or not. Our experimental results show that the proposed technique improves the flash performance up to 4.6% by reducing the unnecessary block erase numbers and page copy numbers.

• Journal of Ocean Engineering and Technology
• /
• v.31 no.2
• /
• pp.121-129
• /
• 2017

The present study numerically investigated the influence of the waveform distribution on the tsunami-vegetation interaction using a non-reflected wave generation system for various tsunami waveforms in a two-dimensional numerical wave tank. First, it was possible to determine the wave attenuation mechanism due to the tsunami-vegetation interaction from the spatial waveform, flow field, vorticity field, and wave height distribution. The combination of fluid resistance in the vegetation and a large gap and creates a vortex according to the flow velocity difference in and out of the vegetation zone. Thus, the energy of a tsunami was increasingly reduced, resulting in a gradual reduction in wave height. Compared to existing approximation theories, the double volumetric ratio of the waveform increased the reflection coefficient of the tsunami-vegetation interaction by 34%, while decreasing the transfer coefficient and energy attenuation coefficient by 25% and 13%, respectively. Therefore, the hydraulic characteristics of a tsunami is highly likely to be underestimated if the solitary wave of the approximation theory is applied for the tsunami.

• Journal of the Korean Wood Science and Technology
• /
• v.47 no.6
• /
• pp.700-708
• /
• 2019

To verify the possibility of using resistograph to estimate the age of big old living trees, we selected three Zelkova serrata and seven Pinus densiflora in Goesan. The mean diameters at breast height of Z. serrata and P. densiflora were 102 (92-116) cm and 80 (65-110) cm, respectively. The heights measured from the ground using a resistograph ranged at 1.2-4.3 m and 0.6-1.1 m for Z. serrata and P. Densiflora, respectively. The most appropriate needle speed to determine tree-ring boundaries for measuring ring width was 1500 r/min for both tree species. Alternatively, the suitable feed speeds for Z. serrata and P. densiflora were 50 cm/min and 150 cm/min, respectively. From the measured data, the mean numbers of tree rings of Z. serrata and P. densiflora were 57 (43-68) and 104 (93-124), respectively, and the mean tree-ring widths were 4.27 mm (3.18-5.09 mm) and 2.93 mm (2.32-3.34 mm), respectively. A comparison between the time series of tree-ring widths by resistograph and that from the local master chronologies tallied for the heartwood part. Finally, this study showed that resistograph can be used to estimate tree ages when a local master chronology is available.

• Steel and Composite Structures
• /
• v.19 no.2
• /
• pp.309-325
• /
• 2015

A convenient procedure for seismic retrofit of existing buildings is to use passive control methods, like using friction dampers in steel frames with bracing systems. In this method, reduction of seismic demand and increase of ductility generally improve seismic performance of the structures. Some of its advantages are development of a stable rectangular hysteresis loop and independence on environmental conditions such as temperature and loading rate. In addition to friction dampers, masonry-infill panels improve the seismic resistance of steel structures by increasing lateral strength and stiffness and reducing story drifts. In this study, the effect of masonry-infill panels on seismic performance of a three-span four-story steel frame with Pall friction dampers is investigated. The results show that friction dampers in the steel frame increase the ductility and decrease the drift (to less than 1%). The infill panels fulfill their function during the imposed drift and increase structural strength. It can be concluded that infill panels together with friction dampers, reduced structural dynamic response. These infill panels dissipated input earthquake energy from 4% to 10%, depending on their thickness.

• Journal of Radiopharmaceuticals and Molecular Probes
• /
• v.5 no.1
• /
• pp.36-47
• /
• 2019

Hypoxia-inducible factor-1 ($HIF-1{\alpha}$) is a transcription factor activated in response to low oxygen level, and is highly expressed in many solid tumors. Moreover, $HIF-1{\alpha}$ is a representative biomarker of hypoxia and also helps to maintain cell homeostasis under hypoxic condition. Most solid tumors show hypoxia, which induces poor prognosis and resistance to conventional cancer therapies. Thus, early diagnosis of hypoxia with positron emission tomography (PET) radiotracer would be highly beneficial for management of malignant solid tumors with effective cancer therapy. YC-1 is a most promising candidate among several $HIF-1{\alpha}$ inhibitors. As an effort to develop a hypoxia imaging tool as a PET radiotracer, we designed and synthesized [$^{18}F$]DFYC based on potent derivative of YC-1 and performed preliminary in vitro cell uptake study. [$^{18}F$]DFYC showed a significant accumulation in SKBR-3 cells among other cancer cells, proving as a good lead to develop a hypoxic solid tumor such as breast cancer.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.6
• /
• pp.3280-3298
• /
• 2019

Vehicular ad-hoc networks (VANETs) have become increasingly significant in intelligent transportation systems, they play a great role in improving traffic safety and efficiency. In the deployment of intelligent VANETs, intelligent vehicles can efficiently exchange important or urgent traffic information and make driving decisions. Meanwhile, secure data communication and vehicle's identity privacy have been highlighted. To cope with these security issues, in this paper, we construct an efficient anonymous authentication scheme with secure communication in intelligent VANETs. Combing the ElGamal encryption technique with a modified Schnorr signature technique, the proposed scheme provides secure anonymous authentication process for encrypted message in the vehicle-to-infrastructure communication model, and achieves identity privacy, forward security, and reply attack resistance simultaneously. Moreover, except the trusted authority (TA), any outside entity cannot trace the real identity of an intelligent vehicle. The proposed scheme is designed on an identity-based system, which can remove the costs of establishing public key infrastructure (PKI) and certificates management. Compared with existing authentication schemes, the proposed scheme is much more practical in intelligent VANETs.

• Journal of Preventive Medicine and Public Health
• /
• v.52 no.1
• /
• pp.66-70
• /
• 2019

Objectives: In the Republic of Korea (ROK), the notified incidence of tuberculosis in foreign-born individuals (NITFBI) has increased recently, as has the rate of multidrug-resistant (MDR) and rifampicin-resistant (RR) tuberculosis in foreigners staying in the ROK. As Jeju Province in ROK has a no-visa entry policy, control programs for NITFBI should be consolidated. The aim was to evaluate the status of NITFBI, with a focus on the distribution of MDR/RR tuberculosis by nationality. Methods: Data on tuberculosis incidence in individuals born in Jeju Province and in foreign-born individuals were extracted from the Korean Statistical Information Service of Statistics Korea, and the Infectious Disease Surveillance Web Statistics of the Korea Centers for Disease Control and Prevention, respectively. Results: Among all notified incident cases of tuberculosis, the proportion of NITFBI increased from 1.46% in 2011 to 6.84% in 2017. China- and Vietnam-born individuals accounted for the greatest proportion of the 95 cases of NITFBI. Seven cases of MDR/RR tuberculosis were found, all involving patients born in China. Conclusions: In Jeju Province, ROK, NITFBI might become more common in the near future. Countermeasures for controlling active tuberculosis in immigrants born in high-risk nations for tuberculosis should be prepared in Jeju Province, since it is a popular tourist destination.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.3
• /
• pp.223-228
• /
• 2019

We fabricated a printed Ag:CNT film as a liquid sensor for the detection of HNS (hazardous and noxious substances) in seawater. The paste required for printing was prepared using Ag powder, MWCNTs (multi-walled carbon nanotubes), and an organic binder. The heat treatment process for binder removal was optimized. In order to confirm that the sensor was operational, the resistance change characteristics in brine (3.5%) and methanol (99.8%) were assessed at $20^{\circ}C$. EDL (electrical double layer) formation and redox reactivity were confirmed as the most important reactions affect each electrical property of sensor in brine and methanol. From these results, it was determined that printed Ag:CNT film can be applied as a sensor to detect HNS in seawater.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.22 no.1
• /
• pp.41-49
• /
• 2019

Recent studies on pediatric inflammatory bowel disease (IBD) have revealed that early-onset IBD has distinct phenotypic differences compared with adult-onset IBD. In particular, very early-onset IBD (VEO-IBD) differs in many aspects, including the disease type, location of the lesions, disease behavior, and genetically attributable risks. Several genetic defects that disturb intestinal epithelial barrier function or affect immune function have been noted in these patients from the young age groups. In incidence of pediatric IBD in Korea has been increasing since the early 2000s. Neonatal or infantile-onset IBD develops in less than 1% of pediatric patients. Children with "neonatal IBD" or "infantile-onset IBD" have higher rates of affected first-degree relatives, severe disease course, and a high rate of resistance to immunosuppressive treatment. The suspicion of a monogenic cause of VEO-IBD was first confirmed by the discovery of mutations in the genes encoding the interleukin 10 (IL-10) receptors that cause impaired IL-10 signaling. Patients with such mutations typically presented with perianal fistulae, shows a poor response to medical management, and require early surgical interventions in the first year of life. To date, 60 monogenic defects have been identified in children with IBD-like phenotypes. The majority of monogenic defects presents before 6 years of age, and many present before 1 year of age. Next generation sequencing could become an important diagnostic tool in children with suspected genetic defects especially in children with VEO-IBD with severe disease phenotypes. VEO-IBD is a phenotypically and genetically distinct disease entity from adult-onset or older pediatric IBD.

• Journal of the Korean Medical Association
• /
• v.61 no.11
• /
• pp.655-661
• /
• 2018

Incidence of basal and squamous cell carcinoma is increasing among Korean. With increasing this incidence we need to attend the management and prevention of these cutaneous malignancies. Basal cell carcinoma (BCC) is the most common skin malignancy. Sun exposure is the most important environmental cause of BCC. Daily sun protection especially avoiding sun exposure between 10 a.m. and 4 p.m. provides most effective prevention against chronic ultraviolet-induced skin damage. Hedgehog pathway inhibitors are used locally advanced and metastatic BCC lesions in Korea. Until recently, there are no reports whether it developed resistance of Hedgehog pathway inhibitors with advanced BCC in Korean patients. Among malignant skin tumors, 19.1% were squamous cell carcinoma (SCC). The incidence of SCC was rapidly increased over the past years. However, the incidence rate of SCC in Japan has not been changed from the period 1976-1980 to 1986-1990. Sentinel lymph node biopsy for SCC did not provide diagnostic value. Bowen's disease and Erythroplasia of Queyrat are considered as carcinoma in situ of the skin. Erythroplasia of Queyrat have worse prognosis with a higher rate of malignant degeneration. Dermoscopy may helpful tool in assisting the noninvasive diagnosis of carcinoma in situ of the skin.