• Microbiology and Biotechnology Letters
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• v.7 no.3
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• pp.141-147
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• 1979

Naringinase from Atpergillus nidulans was immobillized on DEAE-Sephadex A-25 and its characteristics were studied. The optimal conditions for the preparation of the immobilized enzyme were as follow; optimal pH, incubation time and the suitable amount of enzyme were 6.0, 30 min. and 110 units per gram of the dried ion exchage resin, respectively. The optimal pH of the immobilized enzyme was higher than that of the native enzyme. The optimal temperature increased from 4$0^{\circ}C$ to 5$0^{\circ}C$. The heat and pH stability of the immobillized enzyme were better than those of the native enzyme. No significant difference in the Michaelis constant was detected. Activation energy of the immobilized enzyme was 7.96 Kcal/mole, and the apparent Michaelis rate equation was used to describe the action of this material. The degree of hydrolysis was dependant on the flow rate at low rate of perfusion through the column. As the flow rate increased, the value of the apparent Km decreased.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.199-204
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• 2018

Smart phones that have lost their existing physical home buttons are being released at the same time, and the flow of users is also changing. The flow is highly subjective and can vary depending on the individual's tendencies. Therefore, this study investigated the change of the flow of smart phone users by Q methodology which is a method of subjectivity research. As a result, the proficiency level of how to turn on the power to start the screen showed a tendency to decrease the flow, and the playability, which is a result of curiosity about the new thing, The results were very positive in the continuity of navigation due to the use of software buttons instead of buttons. Therefore, it can be seen that the change in the hardware smartphone has a positive effect on the flow.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.51-56
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• 2017

With the rapid increase in the number of mobile terminals, demand for wireless technologies has sharply increased these days. While wireless communication provides advantages such as ease of deployment, mobility of terminals, continuity of session, and almost comparable transmission bandwidth to the wired communication, it has vulnerability to malicious radio attacks such as eavesdropping, denial of service, session hijacking, and jamming. Among a variety of methods of preventing wireless attacks, the MTD(Moving Target Defense) is the technique for improving the security capability of the defense system by constantly changing the ability of the system to be attacked. In this paper, in order to develop a resilient software defined radio communication testbed system, we present a novel MTD approach to change dynamically and randomly the radio parameters such as modulation scheme, operating frequency, packet size. The probability of successful attack on the developed MTD-based SDR communication system has been analysed in a mathematical way and verified through simulation.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2
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• pp.35-43
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• 2001

Many speech recognition systems have used pronunciation lexicon with possible multiple phonetic transcriptions for each word. The pronunciation lexicon is of often manually created. This process requires a lot of time and efforts, and furthermore, it is very difficult to maintain consistency of lexicon. To handle these problems, we present a model based on morphophon-ological analysis for automatically generating Korean pronunciation variants. By analyzing phonological variations frequently found in spoken Korean, we have derived about 700 phonemic contexts that would trigger the multilevel application of the corresponding phonological process, which consists of phonemic and allophonic rules. In generating pronunciation variants, morphological analysis is preceded to handle variations of phonological words. According to the morphological category, a set of tables reflecting phonemic context is looked up to generate pronunciation variants. Our experiments show that the proposed model produces mostly correct pronunciation variants of phonological words. Then we estimated how useful the pronunciation lexicon and training phonetic transcription using this proposed systems.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.4
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• pp.436-442
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• 1987

The variations of the anther and pistil length of some rice cultivars at the different planting density and fertility levels were tested and their inheritance mode was studied. The anther length of a spikelet on a secondary panicle branch was longer than the one of a spikelet on a primary panicle branch. In the cultivar Z97B, both the anther and the pistil length were increased slightly along the increased plant-ing spacings, But, in the cultivar IR43 no general tendency was observed. The fertilizer levels applied n the field did not affect both the anther and pistil length of a given cultivar. In a cross of IR56/IR8, the anther length showed continuous variation with longer anther being recessive in the F2 population. While, the pistil length showed a continuous variation with longer pistil being over-dominance. In all of the crosses which IR56 involved, the general and specific combining abilities were high for both the anther and pistil length. The broad sense heritability for anther length was 0.46, and for pistil length was 0.88. The correlation coefficients of anther length and pistil length were 0.33 for phenotypic and 0.44 for geno-typic.

• Journal of Life Science
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• v.13 no.3
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• pp.252-257
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• 2003

The genetic variabilities of second chromosomes of Drosophila melanogaster concealed in Busan natural and experimental populations have been analyzed by the Cy//Pm method. The experimental population was composed of D. melanogaster which had the lethal-free second chromosome, collected Sasang natural population in 1982. The frequencies of deleterious genes were estimated to be 14.3∼25.4% in Busan natural population and 26.5∼27.2% in experimental population. The allelism rates in lethal genes isolated from the natural and experimental populations were calculated to be about 0.76% and 9.76∼14.17%, respectively. The value of elimination by the frequencies of deleterious genes and allelism rate was 0.0106and the effective population size estimated to be about 430 flies at the 6570 days population.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2023.04a
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• pp.30-30
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• 2023

한국산 체꽃속(Scabiosa L.)의 외부형태형질을 바탕으로 구분한 5가지 변이 유형[솔체꽃(S. comosa) Type 1-2, 체꽃(S. tschiliensis f. pinnata) Type 3-4, 구름체꽃(S. tschiliensis f. alpina) Type 5]에 대해 잎 표피와 화분의 미세구조를 관찰하였다. 잎 표피세포의 크기는 향축면은 평균 12.4 × 6.7 ㎛로, Type 1이 가장 작고 Type 3가 가장 컸으며, 배축면은 평균 9.4 × 4.6 ㎛로 모든 유형이 비슷하게 나타났다. 모용은 단세포성 선상 모용이 일부 유형에서, 다세포성 비선상 모용이 모든 유형에서 관찰되었다. 선상 모용은 향축면에서 Type 1과 5에만 있었으며, 두 유형 중 Type 5의 모용이 길이 72.2 ㎛로 더 길고, 단위면적 (0.01 mm²) 당 개수도 5개로 더 많았다. 배축면에서는 Type 1, 3 및 5에 있고, 단위면적 당 개수가 Type 1과 5는 3~6개로 비슷하였으나, Type 3은 1개 이하로 매우 드물게 나타났다. 기공복합체는 부등형으로 양면에 분포하며, 향축면의 공변세포 크기는 평균 4.4 × 2.7 ㎛로 너비는 유사하나 길이는 Type 1과 5가 3.1 ㎛, 3.9 ㎛로 나머지에 비해 작았다. 단위면적 당 기공의 수는 향축면과 배축면이 평균 40.2개, 149.2개이고, 양면 모두 Type 1이 66.3개와 177.2개로 가장 많았다. 화분은 모두 단립으로 삼구형이고, 극축 길이(P)와 적도면 지름(E)의 비율은 0.83~1.12로 모양은 아단구형~약장구형이다. 표면무늬는 과립상 표면에 자상 돌기가 있고, Type 3과 4에서만 유공상이 확인되었다. 이상의 결과에서, 솔체꽃 유형인 Type 1과 2가 잎 표면의 선상 모용 유무 및 기공의 수에 뚜렷한 차이를 보여 Type 1은 솔체꽃과는 다른 새로운 변종 또는 품종일 가능성이 있다고 생각된다. 또한 체꽃 유형인 Type 3과 4의 경우, Type 3의 잎 배축면에 털이 드물게 있으나, 두 유형의 화분 표면무늬가 동일하고, 다른 형질들도 모두 중복되어 연속적인 변이로 보이며, 구름체꽃 유형인 Type 5는 나머지 유형과 뚜렷이 구분되었다.

• KDI Journal of Economic Policy
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• v.34 no.1
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• pp.169-197
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• 2012

It is often argued that the parental leave should be extended in order to help employees achieve the balance of work and family life. However, one should be careful in designing the parental leave since there is a tradeoff between the continuity of employment after childbearing and the depreciation of human capital due to the time off the work. The paper investigates whether the parental leave payment introduced in Korea in 2001 helped women's take-up of the leave and employment after giving birth. The results are as follows. First, the increase in the payment indeed raised the female take-up of the leave. Second, women returned to labor market less often after giving birth in the short run, but the size of the effect tends to decrease in the long run. However, the negative effect on returning to the same workplace after the birth remains significant in the long run. Lastly, there is no evidence that the share of women of childbearing age at workplace changed due to the increase in the parental leave payment. Although there is a limitation in that the analysis is based only on the employment covered by the Employment Insurance, these findings imply that the increase in the parental leave payment may not be an effective policy tool for promoting female labor market participation. On the other hand, it should be noted that it is necessary to pay attention to child development as well as female employment as an objective in order to make an overall judgement on the parental leave policy.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.669-677
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• 2009

Twenty-four beam specimens were tested to examine the effect of the maximum aggregate size on the shear behavior of lightweight concrete continuous beams. The maximum aggregate size varied from 4 mm to 19 mm and shear span-to-depth ratio was 2.5 and 0.6 in each all-lightweight, sand-lightweight and normal weight concrete groups. The ratio of the normalized shear capacity of lightweight concrete beams to that of the company normal weight concrete beams was also compared with the modification factor specified in ACI 318-05 for lightweight concrete. The microphotograph showed that some unsplitted aggregates were observed in the failure planes of lightweight concrete beams, which contributed to the enhancement of the shear capacity of lightweight concrete beams. As a result, the normalized shear capacity of lightweight concrete continuous beams increased with the increase of the maximum aggregate size, though the increasing rate was lower than that of normal weight concrete continuous beams. The modification factor specified in ACI 318-05 was generally unconservative in the continuous lightweight concrete beams, showing an increase of the unconservatism with the increase of the maximum aggregate size. In addition, the conservatism of the shear provisions of ACI 318-05 was lower in lightweight concrete beams than in normal weight concrete beams.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.4
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• pp.272-279
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• 2002

The time-dependent frequency and energy of free vibration of the spagetti problem, that is the axially moving continuum with time-varying length, are investigated. Exact expressions for the natural frequency and time-varying vibration energy are derived by dealing with traveling waves. The vibration period increases with increasing length, but the free vibration energy decreases. When the string undergoes retraction, the vibration energy increases with time. The free response of the time-varying string is represented by superposing two traveling waves.