• Earthquakes and Structures
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• v.20 no.4
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• pp.389-403
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• 2021

Skewed bridges, being irregular structures with complicated dynamic behavior, are more susceptible to earthquake damage. Reliable seismic-resistant design of skewed bridges can be achieved by accurate determination of nonlinear seismic demands. However, the effect of geometric characteristics on the response modification factor (R-factor) is not accounted for in bridge design practices. This study attempts to investigate the effects of changes in the number of spans, skew angle and bearing stiffness on R-factor values and to assess the seismic fragility of skewed bridges. Results indicated that changes in the skew angle had no significant effect on R-factor values which were in consonance with code-prescribed R values. Also, unlike the increase in the number of spans that resulted in a decrease in the R-factor, the increase in bearing stiffness led to higher R-factor values. Findings of the fragility analysis implied that although the increase in the number of spans, as well as the increase in the skew angle, led to a higher failure probability, greater values of bearing stiffness reduced the collapse probability. For practicing design engineers, it is recommended that maximum demands on substructure elements to be calculated when the excitation angle is applied along the principal axes of skewed bridges.

• Korean Journal of Pharmacognosy
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• v.50 no.1
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• pp.1-10
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• 2019

Recently, companion animal culture has grown rapidly and mature, raising interest in preventing and treating animal diseases. In particular, viral infection was a serious threat to companion animal health because there was no proper antiviral drugs. Synthetic antiviral drugs have limitations such as low efficiency, toxicity, and occurrence of resistant viruses. Therefore, attempts to find new anti-viral drugs from natural sources have continued. This review focused on the natural products and active substances that exhibit antiviral activity against three viruses: canine distemper virus (CDV), canine parvovirus (CPV), and feline calicivirus (FCV) that cause fatal diseases in dogs and cats. Natural plant extracts, flavonoids, polysaccharides, alkaloids and saponins showed antiviral activity with various mechanisms and differences in activity depending on the structure. Especially, quercetin and epigallocatechin-3-gallate (EGCG) showed antiviral activity through a multi-mechanism that interferes with the attachment and penetration stages of the virus and inhibits the viral polymerase within the cell. Some natural plant extracts showed a virucidal activity and showed the potential effect as a preventative agent to prevent the viral infection. This review is expected to provide research trend on the development of antiviral natural products for companion animals.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.1
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• pp.137-146
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• 2020

In this study, various application schemes of seismic isolation system which can be applied to Hanok have been studied by analyzing its structural characteristics under seismic load. Structural stability of Hanok is more required against seismic load as Hanok becomes long-spanned and multi-storied. To meet this goal, it becomes necessary to study more advanced technology such as seismic isolation design as well as seismic control design and seismic resistant design suitable to Hanok. Seismic isolation systems have been successfully applied to RC and steel structures to improve structural performance during earthquakes. Based on these previous study, we proposed four application schemes of seismic isolation design suitable for Hanok and analyzed their structural characteristics and applicability to Hanok in conceptual level based on its structural characteristics. The proposed four schemes are base isolation method, ground isolation method, roof isolation method and intermediate-story isolation method. The applicability of the proposed method was evaluated by performing boundary nonlinear dynamic analysis to the typical Hanok for the two types of isolation method, that is, ground isolation method and roof isolation method, and the results showed that the proposed methods produced good performance enough to be applied to Hanok.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.2
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• pp.91-99
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• 2023

Structural vibration induced by earthquake hazards is one of the most significant concerns in structure performance-based design. Structural hazards evoked from seismic events must be properly identified to make buildings resilient enough to withstand extreme earthquake loadings. To investigate the effects of combined earthquake-resistant systems, shear walls and five types of dampers are incorporated in nineteen structural models by altering their arrangements. All the building models were developed as per ACI 318-14 and ASCE 7-16. Seismic fragility curves were developed from the incremental dynamic analyses (IDA) performed by using seven sets of ground motions, and eventually, by following FEMA P695 provisions, the collapse margin ratio (CMR) was computed from the collapse curves. It is evident from the results that the seismic performance of the proposed combined shear wall-damper system is significantly better than the models equipped with shear walls only. The scrutinized dual seismic resisting system is expected to be applied practically to ensure a multi-level shield for tall structures in high seismic risk zones.

• Tuberculosis and Respiratory Diseases
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• v.60 no.3
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• pp.285-289
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• 2006

Background : North Korea's economic and public health problems began in the early 1990s as a result of the gradual loss of economic support from its communist allies, combined with an inordinate number of natural disasters. The decline in public health has increased the incidence of tuberculosis in North Koreans and refugees. This study investigated tuberculosis situation in North Korean refugees in order to prepare for the future impact of tuberculosis control in Korea. Material and Methods : From 2001 to 2005, tuberculosis patients among North Korean refugees who were diagnosed before or after arriving in South Korea, based on the official records of OO hospital, were enrolled in this study. The demographic and clinical data of the cases were evaluated retrospectively. Results : A total of 42 TB cases were reviewed during the study period. Of these, 37 (88.1%) cases were pulmonary TB. based on the cases identified among the number of North Korean refugees' arriving each year, the annual incidence of pulmonary TB were 900 per 100,000 in 2004, 700 in 2003, The number of smear-positive patients was 20 (47.6%) and the number of culture-positive patients was 18 (42.9%). Of the M. tuberculosis isolates, 2 cases were found to be susceptible to all anti-TB drugs available, 4 were resistant to isoniazid, and 3 were multi-drug resistant. Conclusion : The prevalence of pulmonary TB in North Korean Refugees is high. In addition, North Korean refugees suffer from more severe tuberculosis in bacteriological and radiological aspects.

• Tuberculosis and Respiratory Diseases
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• v.59 no.3
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• pp.250-256
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• 2005

Background : Fluoroquinolone drugs are an important anti-tuberculous agent for the treatment of multi-drug resistant tuberculosis. However, many drugs belonging to the fluoroquinolones have different cross resistance to each other. Methods : Sixty-three ofloxacin (OFX) resistant and 10 pan-susceptible M. tuberculosis isolates were selected, and compared for their cross resistance using a proportion method on Lowenstein-Jensen media, containing ofloxacin (OFX), ciprofloxacin (CIP), levofloxacin (LVX), moxifloxacin (MXF), gatifloxacin (GAT) and sparfloxacin (SPX), at concentrations ranging from 0.5 to $3{\mu}g/ml$. DNA extracted from the isolates was directly sequenced after amplifying from the gyrA and gyrB genes. Results : The 63 OFX resistant M. tuberculosis isolates showed complete cross resistance to CIP, but only 90.5, 44.4, 36.5 and 46.0% to LVX, MXF, GAT, and to SPX, respectively. Fifty-one of the isolates (81.0%) had point mutations in codons 88, 90, 91 and 94 in gyrA, which are known to be correlated with OFX resistance. The Gly88Ala, Ala90Valand Asp94Ala mutations in gyrA showed a tendency to be susceptible to MXF, GAT and SPX. Only 4 isolates had mutations in the gyrB gene, which did not affect the OFX resistance. Conclusion : About 60% of the OFX resistant M. tuberculosis isolates were susceptible to GAT, SPX and MXF. These fluoroquinolones may be useful in the treatment of TB patients showing OFX resistance.

• Journal of Life Science
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• v.26 no.7
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• pp.835-846
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• 2016

Chemo-resistance is the biggest issue of effective cancer therapy. ABCG2 is highly correlated with multi-drug resistance, and represent a typical phenotype of multiple cancer stem-like cells. Accumulating evidence recently reported that oncolytic viruses represent a new strategy for multiple aggressive cancers and drug resistant cancers including cancer stem cell-like cells and ABCG2 expressing cells. In this study, we generated an evolutionally engineered vaccinia virus, SLJ-496, for drug-resistant cancer therapy. We first showed that SLJ-496 treatment enhanced tumor affinity using cytopathic effect assay, plaque assay, as well as cell viability assay. Next, we clearly demonstrated that in vitro SLJ-496 treatment represents significant cytotoxic effect in multiple cancers including colorectal cancer cells (HT-29, HCT-116, HCT-8), gastric cancer cells (AGS, NCI-N87, MKN-28), Hepatocellular carcinoma cells (SNU-449, SNU-423, SNU-475, HepG2), as well as mesothelioma cell (NCI-H226, NCI-H28, MSTO-221h). Highly ABCG2 expressing HT-29 cells represent cancer stem like phenotype including stem cell marker expression, and self-renewal bioactivities. Interestingly, we demonstrated that in vitro treatment of SLJ-496 showed significant cytotoxicity effect, as well as viral replication capacity in ABCG2 overexpressing cell. In addition, we also demonstrated the cytotoxic effect of SLJ-496 in Adriamycin-resistant cell lines, SNU-620 and ADR-300. Taken together, these findings provide us a pivotal clue that cancer therapy using SLJ-496 vaccinia virus might be new therapeutic strategy to overcome ABCG2 expressing cancer stem-like cell and multiple chemo-resistance cancer cells.

• Journal of Life Science
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• v.33 no.12
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• pp.1015-1024
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• 2023

Antibiotics have greatly contributed to the treatment and prevention of bacterial diseases in humans, animals, and fish. However, antibiotic misuse has led to the emergence and spread of multidrug-resistant bacteria. In addition to antibiotic discovery research, efforts are being made to combat such multidrug-resistant bacteria using antimicrobial agents, antioxidants, host immune enhancement, probiotics, and bacteriophages, as well as various symptomatic therapies. To discover novel bioactive compounds, it is crucial to adopt approaches that incorporate fresh ideas, new targets, innovative techniques, and untapped resources. Halophytes are plants that grow in high-salt soils and are known to adapt to salt-induced stress through unique metabolic processes that produce secondary metabolites. This study aimed to investigate the effects of extracts of halophytes native to Korea on oxidative stress and to determine whether they exert inhibitory activity against biofilms, which are major pathogenic factors of infectious bacteria. The Acinetobacter baumannii strain ATCC 17978, a representative drug-resistant bacterium, was used to measure anti-biofilm activity. The results showed that Aster spathulifolius, Carex kobomugi, Rosa rugosa, and Asparagus cochinchiensis exerted strong antioxidant and anti-biofilm effects without affecting bacterial growth itself. The halophytes used in this study are promising candidates for the development of pharmaceutical agents with antioxidant and antimicrobial properties.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.3
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• pp.402-413
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• 2001

Food safety is a term broadly applied to food quality that may adversely affect human health. These include zoonotic diseases and acute and chronic effects of ingesting natural and human-made xenobiotics. There are two major areas of concern over the presence of residues of antibiotics in animal-derived foodstuffs with regard to human health. The first is allergic reactions. Some antibiotics, such as penicillins can evoke allergic reactions even though small amounts of them are ingested or exposed by parenteral routes. The second is development of antibiotic resistance in gut bacteria of human. Recently multi-resistant pneumococcal, glycopeptide-resistant enterococci and gram negative bacteria with extended-spectrum $\beta$-lactamases have spread all over the world, and are now a serious therapeutic problem in human. Although it is evident that drugs are required in the efficient production of meat, milk and eggs, their indiscriminate use should never be substituted for hygienic management of farm. Drug should be used only when they are required. In addition to veterinary drugs, environmental contaminants that were contaminated in feed, water and air can make residues in animal products. Mycotoxins, heavy metals, pesticides, herbicides and other chemicals derived from industries can be harmful both to animal and human health. Most of organic contaminants, such as dioxin, PCBs and DDT, and metals are persistent in environment and biological organisms and can be accumulated in fat and hard tissues. Some of them are suspected to have endocrine disrupting, carcinogenic, teratogenic, immunodepressive and nervous effects. The governmental agencies concerned make efforts to prevent residue problems; approval of drugs including withdrawal times of each preparation of drugs, establishment of tolerances, guidelines regarding drug use and sanitation enforcement of livestock products. National residue program is conducted to audit the status of the chemical residues in foods. Recently HACCP has been introduced to promote food safety from farm to table by reducing hazardous biological, chemical and physical factors. Animal Production Food Safety Program, Quality Assurance Programs, Food Animal Residue Avoidance Databank are para- or non-governmental activities ensuring food safety. This topic will cover classification and usage or sources of chemical residues, their adverse effects, and chemical residue status of some countries. Issues are expanded to residue detection methodologies, toxicological and pharmacokinetic backgrounds of MRL and withdrawal time establishments, and the importance of non-governmental activities with regard to reducing chemical residues in food.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.118-125
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• 2013

Antibiotic susceptibility was examined for 596 Salmonella isolates from patients with acute gastroenteritis during 2000-2009 in Gwangju area in South Korea. Of 16 antibiotics tested, ampicillin resistance (43%) was the most commonly observed resistance among the 596 Salmonella sp. isolates, followed by tetracycline (35.9%), nalidixic acid (31.5%), and chloramphenicol (26.2%). Antibiotic resistance varied among serotypes: The highest resistance of S. Enteritidis and S. Typhimurium was to ampicillin (51.1%) and tetracycline (77.9%), respectively. A total of 89 resistance patterns were observed, and 26% (155/596) of Salmonella isolates were susceptible to all antibiotics tested in this study. About 21% (127/596) and 15% (87/596) of the isolates were resistant to one and two antibiotics, respectively. The rest of Salmonella isolates (227/596, 38%) were resistant to three or more antibiotic agents. The highest multi-drug resistance (MDR) was observed in serotype S. Paratyphi B (76.5%), followed by S. Typhimurium (58.2%), and S. Enteritidis (40.2%). The most common resistance pattern of MDR isolates was ampicillin-chloramphenicol-nalidixic acid-ticarcillin (36/227, 15.8%), most of which (35/36, 97.2%) were S. Enteritidis.