• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.244-250
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• 1990

A bacterium capable of hydrotyzing raw starch was isolated from soil, which was identified as a strain of Bacillue. The effects of culture conditions and medium compositions on the enzyme production were investigated. Among tested carbon sources, soluble starch and wheat starch were most effective for the production of the enzyme, and the level of concentration for the optimal enzyme production was 0.5%. For nitrogen sources, polypeptone was best for the enzyme production, with the level of 0.5%. The enzyme was maximally produced by cultivating the organism at medium of initial pH 6.5, and temperature of $35^{\circ}C$. The enzyme was partially purified by Sepharose CL-6B gel filtration and DEAESephacel ion-exchange chromatography. The optimal pH and temperature for the enzyme reaction were 6.5 and $70^{\circ}C$, respectively. The enzyme most stable at pH 8.0, and temperature up to $60^{\circ}C$. In kinetic studies, the k, values for corn, wheat, rice and potato starch were 1.7, 1.4,2.5 and 1.090, respectively.

• Journal of Life Science
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• v.25 no.1
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• pp.113-120
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• 2015

Osteoporosis is a major bone disorder defined as having bone mineral density (BMD) of 2.5 standard deviations or more below the peak bone mass. Osteoporosis will increasingly be a major disorder that faces the aging mankind. It is the result of an imbalance in the bone remodeling system, where bone constantly undergoes a cycle of resorption by osteoclasts and formation by osteoblasts. Estrogen deficiency in women following menopause is identified as the predominant reason that causes disparity in this system. Current medical treatments for osteoporosis include hormone replacement therapy (HRT), biphosphonates, and teriparatide, but have various side effects that raise questions concerning their medical safety and practicality. Alternative treatments involving natural product sources are under study to find a safer therapy. Many natural sources including lactoferrin and isoflavones and numerous traditional herbal medicines exhibit anti-resorptive or anabolic effects on bone and thus show promises to provide therapeutic agents in treating osteoporosis. Unfortunately, the majority of natural product treatments are still in its preliminary stages to prove their efficacy even though the development pace of treatment for osteoporosis is astounding in the past few decades. Further progress in pre-clinical studies and the subsequent clinical studies will someday lead to a breakthrough that takes us another step forward in science.

• Journal of Digital Contents Society
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• v.11 no.3
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• pp.375-383
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• 2010

In developing question-answering (QA) systems, it is hard to analyze natural language questions syntactically and semantically and to find exact answers to given query questions. In order to avoid these difficulties, we propose a new style of question-answering system that automatically generate natural language queries and can allow to search queries fit for given keywords. The key idea behind generating natural queries is that after significant sentences within text documents are applied to the named entity recognition technique, we can generate a natural query (interrogative sentence) for each named entity (such as person, location, and time). The natural query is divided into two types: simple type and sentence structure type. With the large database of question-answer pairs, the system can easily obtain natural queries and their corresponding answers for given keywords. The most important issue is how to generate meaningful queries which can present unambiguous answers. To this end, we propose two principles to decide which declarative sentences can be the sources of natural queries and a pattern-based method for generating meaningful queries from the selected sentences.

• Natural Product Sciences
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• v.17 no.2
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• pp.65-79
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• 2011

Reactive oxygen species potentially cause damage to cellular components including lipids, protein and DNA; this oxidative damage plays a key role in the pathogenesis of neurodegenerative disease, cardiovascular disease, metabolic disease and cancer. On the basis of the oxidative stress hypothesis, a number of studies have been performed to search for an efficient and safe antioxidant. Although in vitro studies have provided promising results, only a limited number of natural and synthetic antioxidants have been developed for clinical application due to their low efficacy and side-effects. Thus, the discovery of new antioxidants with marked efficacy and safety has attracted worldwide attention in recent decades. Since plants are recognized as important sources of natural antioxidants, our research has focused on the discovery of new naturally occurring antioxidants from medicinal plants. The purpose of this review is to open a new prospect in the field of search for natural antioxidants from medicinal plants by summarizing our recent findings. Using in vitro bioassay systems such as 2,2-diphenyl-1-picrylhydrazyl, superoxide radical scavenging tests and lipid peroxidation models, we have tested over than 350 species of medicinal plants for their antioxidant activity and selected several of them for further investigation. During the research on the discovery of effective natural antioxidants from the medicinal plants selected, we have isolated several new and known antioxidant compounds that include stilbene glycosides, phenolic glycosides, flavonoids, oligostilbenes, and coumarins. Our results suggest that the presence of antioxidant compounds in the medicinal plants might be associated with the traditional use to treat inflammation, cardiovascular disease and various chronic diseases.

• Journal of the Korean Institute of Landscape Architecture
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• v.24 no.2
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• pp.25-42
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• 1996

During the last two and a half decades, philosophical interest in the aesthetics of nature and environment has been gained momentum. One of the most coherent theories in this arena of debate has been developed over a series of articles by Allen Carlson. The purpose of this paper is to examine Carlson's theory critically and suggest an alternative aspect that remains untouched by his model. Briefly stated, Carlson's view of the appreciation of nature is that it is a matter of under standing nature under suitable scientific categories. His argument, based on the objectivist epistemology, is basically a disjunctive syllogism : a) The concept of appreciation, derived from traditional disinterestedness and Stolnitz's aesthetic attitude, provides an insight into the explanation of aesthetic appreciation of nature, and is objectivistic in the light of its object-oriented character. b) Nature must be appreciated as nature itself, and the natural environmental model is the appropriate loci of our nature appreciation. c) The paradigmatic form of our nature appreciation is order appreciation. d) There can be a correct and objective aesthetic judgment of nature, and the sources of guiding categories pertinent to it is natural science and natural history. In regarding nature as an environment and as natural, his natural environmental model is meaningful. Nevertheless, his stance results in some serious problems : a) The natural environmental model excludes certain very common appreciative responses to nature-responses of a less intellective, more visceral sort. Therefore, the arousal model with appropriate emotions might be one of our characteristic forms of nature appreciation. b) Even if we consider the scientific knowledge as an objective source of our nature appreciation, this gives rise to the question of whether the natural science can be objective or not. Is there an objectivist aesthetic appreciation of nature\ Does aesthetic appreciation of nature need to be science-based\

• Food Science of Animal Resources
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• v.41 no.2
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• pp.173-184
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• 2021

Clean labeling is emerging as an important issue in the food industry, particularly for meat products that contain many food additives. Among synthetic additives, nitrite is the most important additive in the meat processing industry and is related to the development of cured color and flavor, inhibition of oxidation, and control of microbial growth in processed meat products. As an alternative to synthetic nitrite, preconverted nitrite from natural microorganisms has been investigated, and the applications of pre-converted nitrite have been reported. Natural nitrate sources mainly include fruits and vegetables with high nitrate content. Celery juice or powder form have been used widely in various studies. Many types of commercial starter cultures have been developed. S. carnosus is used as a critical nitrate reducing microorganism and lactic acid bacteria or other Staphylococcus species also were used. Pre-converted nitrite has also been compared with synthetic nitrite and studies have been aimed at improving utilization by exploiting the strengths (positive consumer attitude and decreased residual nitrite content) and limiting the weaknesses (remained carcinogenic risk) of pre-converted nitrite. Moreover, as concerns regarding the use of synthetic nitrites increased, research was conducted to meet consumer demands for the use of natural nitrite from raw materials. In this report, we review and discuss various studies in which synthetic nitrite was replaced with natural materials and evaluate pre-converted nitrite technology as a natural curing approach from a clean label perspective in the manufacturing of processed meat products.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.162-165
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• 2003

Differential learning relies on the differentiated values of nodes, whereas the conventional learning depends on the values themselves of nodes. In this paper, I elucidate the differential learning in the framework maximum likelihood learning of linear generative model with latent variables obeying random walk. I apply the idea of differential learning to the problem independent component analysis(ICA), which leads to differential ICA. Algorithm derivation using the natural gradient and local stability analysis are provided. Usefulness of the algorithm is emphasized in the case of blind separation of temporally correlated sources and is demonstrated through a simple numerical example.

• Proceedings of the Korean Society for Language and Information Conference
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• 1996.02a
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• pp.137-146
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• 1996

Our research goal has been the development of a domain independent natural language processing (NLP) system suitable for information retrieval. As part of that research, we have investigated ways to automatically extend the semantics of a lexicon derived from machine-readable lexical sources. This paper details the extraction of thematic roles derived from lexical patterns in a machine-readable dictionary.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1977.10a
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• pp.192-193
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• 1977

It is certainly a difficult work to find out novel-type "practical" antibiotic from natural sources. In fact, chemically modified antibiotics, such as synthetic penicillins, cephalosporins, derivatives of tetracycline, lincomycin, rifamycin and kanamycin are most widely used in medical practice at present. However, as the possibility of success gained by chemical modification is limited, it would be the buty of our applied microbiologists to offer novel antibiotics to chemist and physician without interruption. In this lecture, some practical problems in new antibiotic research will be discussed.(중략)

• The Journal of the Acoustical Society of Korea
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• v.24 no.2E
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• pp.54-60
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• 2005

A new multichannel blind deconvolution algorithm is proposed for speech mixtures. It employs unidirectional filters and normalization of gradient terms in the frequency domain. The proposed algorithm is shown to be approximately nonholonomic. Thus it provides improved convergence and separation performances without whitening effect for nonstationary sources such as speech and audio signals. Simulations using real world recordings confirm superior performances over existing algorithms and its usefulness for real applications.