• Parasites, Hosts and Diseases
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• 제22권1호
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• pp.116-126
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• 1984

The present study was designed to elucidate the recent prevalence of the intestinal protozoa and to demonstrate the relationship on prevalence of the surveyed population with their academic career and living conditions. During the period from May to July 1981, total 2, 735 fecal specimens were collected from the inhabitants of 11 areas in Gyeong-gi Do(province) near by Seoul City, and 6 areas in Jeonra Bug Do, southwestern part of Korea. The samples were fixed with SAF solution and were examined by formalin-ether sedimentation technique. The results are summarised as follows: 1, Overall positive rate of intestinal protozoa was 11. l% : Gyeong-gi Do, 10.7%; Jeonra Bug Do, 11.7%. 2. Five species of intestinal protozoa were detected: Entamoeba histolytica 0.69% : Entamoeba cali 5.52%; Endolimax nana 2.71%, Giardia lamblia 2.23%; lodamoeba biitschlii 0.18%. 3. Highest positive rates among the examined areas were recognized: Incheon City of Gyeong-gi Do, 26.7%; Im-sil Gun(county) of Jeonra Bug Do, 19.9%. 4. By species, E. nana showed the highest prevalence rate (13.74%) in Incheon City, and E. histolytica (2.37%) and E. coli (9.95%) in Im-sil Gun. 5. Prevalence of E. histolytica in rural areas was higher than in urban areas. 6. No significant difference in the prevalence rate by sect and age was recognized, although the group under 10 years and over 60 years were lower than in other age groups. 7, The highest positive rate of E. histolytica was observed in pauper group and significant linearity of prevalence rate of E. histozytica by monthly income was observed. 8. The inhabitants who used conventional latrine showed higher prevalence, 11.5%, than the group of inhabitants who used modified privy. 9. Although no significant difference of positive rate was recognized by academic career, but the lowest prevalence rate was observed in college graduates. 10. Over half of the surveyed population, 64.8% has no experience on anthelmintic practice. Number of anthelmintic application resulted no difference in prevalence. In conclusion, prevalences of intestinal protozoa in Gyeong-gi Do and Jeonra Bug Do decreased remarkably in comparison with those of one decade before. However, economic level, academic career and anthelmintic administration seemed no essential reasons for such declination.

• 한국컴퓨터정보학회지
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• 제14권2호
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• pp.235-244
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• 2006

본 논문은 VoIP 서비스 네트워크에서 UDP, ICMP, Echo, TCP Syn 패킷 등을 조작한 SYN Flooding 방법, TCP/UDP을 이용한 어플리케이션을 통한 DoS 공격, IP Source Address Spoofing과 Smurf을 이용한 공격, 웜과 트로이목마를 혼합한 알려지지 않는 DoS 공격을 하였다. IPS에서 방어를 위한 동적 업데이트 엔진의 필요성을 정의하고, 엔진의 설계 시에 내 외부의 RT통계에서 트래픽 양을 측정하며, 학습모듈과 통계적 공격에 대한 퍼지 로직 엔진모듈을 설계한다. 엔진은 3가지 공격 등급(Attack, Suspicious, Normal)을 판단하여, Footprint Lookup 모듈에서 AND나 OR 연산을 통해 최적의 필터링 엔진 상태를 유지한다. 실험을 통해 IPS 차단 모듈과 필터링엔진의 실시간 업데이트되어 DoS 공격의 차단이 수행됨을 확인하였다. 실시간 동적으로 업데이트되는 엔진과 필터는 DoS 공격으로부터 VOIP 서비스를 보호하여 유비쿼터스 보안성을 강화시킨 것으로 판명되어졌다.

• 한국컴퓨터정보학회논문지
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• 제11권6호
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• pp.165-174
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• 2006

본 논문은 VoIP 서비스 네트워크에서 UDP, ICMP, Echo, TCP Syn 패킷 등을 조작한 SYN Flooding 방법, TCP/UDP을 이용한 어플리케이션을 통한 DoS 공격, IP Source Address Spoofing과 Smurf을 이용한 공격, 웜과 트로이목마를 혼합한 알려지지 않는 DoS 공격을 하였다. IPS에서 방어를 위한 동적 업데이트 엔진의 필요성을 정의하고, 엔진의 설계 시에 내 외부의 RT통계에서 트래픽 양을 측정하며, 학습모듈과 통계적 공격에 대한 퍼지 로직 엔진모듈을 설계한다. 엔진은 3가지 공격 등급(Attack, Suspicious, Normal)을 판단하여, Footprint Lookup 모듈에서 AND나 OR 연산을 통해 최적의 필터링 엔진 상태를 유지한다. 실험을 통해 IPS 차단 모듈과 필터링엔진의 실시간 업데이트되어 DoS 공격의 차단이 수행됨을 확인하였다. 실시간 동적으로 업데이트되는 엔진과 필터는 DoS 공격으로부터 VoIP 서비스를 보호하여 유비쿼터스 보안성을 강화시킨 것으로 판명되어졌다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권3호
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• pp.245-250
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• 2006

The effects of aliphatic hydrocarbons (n-hexadecane and n-dodecane) on the volumetric oxygen mass transfer coefficient $(k_L\;a)$ were studied in flat alveolar airlift reactor and continuous stirred tank reactors (CSTRs). In the flat alveolar airlift reactor, high aeration rates (>2vvm) were required in order to obtain efficient organic-aqueous phase dispersion and reliable $k_La$ measurements. Addition of 1% (v/v) n-hexadecane or n-dodecane increased the $k_La$ 1.55- and 1.33-fold, respectively, compared to the control (superficial velocity: $25.8{\times}10^{-3}m/s$, sparger orifice diameter: 0.5 mm). Analysis of the gas-liquid interfacial area a and the liquid film mass transfer coefficient $k_L$ suggests that the observed $k_La$ increase was a function of the media's liquid film mass transfer. Addition of 1% (v/v) n-hexadecane or n-dodecane to analogous setups using CSTRs led to a $k_La$ increase by a factor of 1.68 and 1.36, respectively (superficial velocity: $2.1{\times}10^{-3}m/s$, stirring rate: 250 rpm). These results propose that low-concentration addition of oxygen-vectors to aerobic microbial cultures has additional benefit relative to incubation in purely aqueous media.

• 한국환경교육학회지:환경교육
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• 제19권2호
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• pp.96-107
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• 2006

Inquiry has great value in environmental education(EE). Being able to see the world environmentally through 'inquiry-based environmental education' can be an important value and goal of EE. In this study, we intended to develop an EE program of measuring activity of dissolved oxygen(DO), based on the theory of 'inquiry-based EE'. Especially, we recognized the potential that DO meter can be used in 'inquiry-based EE', and we tried to develop a model of inquiry-based EE using DO meter. As a result of this research, we present specific models of inquiry-based EE about how to perform measuring activity of DO and how to use the DO meter in laboratories and streams from the perspective of inquiry of water environment. In the process of program development, we considered organization of the inquiry process, use of concept and knowledge, scientific inquiry and insightful inquiry, integration, sustain-ability, content components of 'Environmental Studies for EE', developmental level and in-forest of students. The developed EE model is a scientific inquiry model, pursuing 'explanation' based on data collection. Through this model, we tried to make students see water environment more deeply. The developed program can be applied to various water environments, like laboratories, streams, ponds, etc. It can be more effective inquiry activity if we perform measuring activities simultaneously with PH, electrical conductivity, and turbidity meters.

• 한국작물학회지
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• 제49권4호
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• pp.284-288
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• 2004

The response of dissolved oxygen (DO) concentrations caused significant change in root number, root length, coleoptile length, shoot length and leaf age of seedlings. The genotypic difference in the effect of DO also highly significant (P<0.01) for all of the seedling traits. The number and length of root were extremely inhibited at the condition of $0.39\pm0.09$ DO concentration. While the coleoptile elongated markedly in the lowest DO concentrations, the shoot did not develop. The root growth was improved slightly at the $1.39\pm0.27mg L^{-1}$, however, there were no difference among genotypes at these two low DO concentrations. As the DO concentration become higher, the growth of root and shoot was improved remarkably. Root number, root length and shoot length was significantly different between $20\;and\;30^{\circ}C$ in DO rich and normal conditions, the development of those traits were apparently accelerated in high water temperature, however those traits of seedlings in DO deficiency were not different between the two temperatures except for shoot length. On the other hand the coleoptile length was not affected by the stagnant water temperature; it was stimulated by the low DO concentration. The competition of DO was greater as the seedling density was increased in the stagnant water, therefore the seedlings grown under high density have long and white coleoptiles, and the growth of roots and shoots was retarded severely.

• KSBB Journal
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• 제21권4호
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• pp.241-247
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• 2006

용존산소 센서 및 시스템에서 손실되는 산소량을 보정하기 위해 멸균처리 기법을 도입하였다. 멸균처리 시료의 DO 거동과 비멸균처리 시료의 DO 거동차(${\Delta}$DO)는 시스템의 영향과 무관하게 폐수 자체의 순수한 미생물만이 소모하는 산소변화량을 구하였다. 용존산소 센서로 축산폐수의 시간에 따른 DO거동(-d${\Delta}$DO/dt)을 측정하여 구한 폐수 자체의 미생물에 의한 산소소모속도는 0.00074mg $O_2/{\ell}{\cdot}sec$이었다. 축산폐수의 원액을 희석하여 다양한 BOD값을 갖도록 시료를 제조한 후 DO meter로 측정하여 구한 DO 변화량은 동일한 시료를 5일 BOD 측정방법인 Winkler Azide화 변법으로 구한 BOD값과 선형구간($30{\sim}60$분)에서 97.72%의 높은 상관 선형성을 보였다. 따라서 본 연구의 multi-biosensor 시스템은 축산폐수의 BOD를 짧은 시간에 정확하게 측정할 수 있는 가능성을 제시하였다.

• 한국식품위생안전성학회지
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• 제24권4호
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• pp.307-311
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• 2009

The objectives of this study were to compare the biochemical profiles with biogroups for the identification of Cronobacter spp. (formally known as Enterobacter sakazakii) isolates using biochemical identification kits. A total of 38 Cronobacter spp. contained 5 clinical, 31 food, and 2 environmental isolates were used. All isolates were identified as Cronobacter spp. with the Vitek II system and ID 32E kit. The API 20E kit identified all isolates as Cronobacter spp. but the percentage identification was 51.1% for 16 of 38 isolates. These strains were contained to Biogroup 2, 9, 10, and 11. The utilization of inositol is a factor determining the percentage identification of Cronobacter spp. with the API 20E kit.

• 한국산학기술학회논문지
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• 제9권2호
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• pp.395-400
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• 2008

본 논문은 GPS 신호를 수신할 때 재머신호의 제거를 위한 성능 개선을 목적으로 2차원 원형 배열 안테나를 이용한 도래각(DoA : Direction of Arrival) 추정 알고리즘의 성능 분석에 관한 것이다. 배열 안테나를 사용하여 DoA를 추정한 후 공간 필터링을 수행함으로서 원하지 않는 방향으로부터의 재머신호를 널링(nulling)시키고, 원하는 방향으로의 빔을 형성하므로서 수신 신호의 품질을 개선할 수 있다. 논문에서는 4 소자와 7 소자 원형 배열 안테나에서 재머신호의 각도와 전력을 고정시킨 후 DoA 추정을 위하여 MUSIC, MinNorm 알고리즘을 적용한다. 이들 알고리즘의 성능 분석을 위하여 추정 결과와 추정 오차를 컴퓨터 시뮬레이션을 통하여 계산한다. 추정 결과 신호대 잡음비가 양호한 경우 Azimuth각과 Elevation각 추정에서는 MUSIC과 MinNorm이 우월하며, 신호대 잡음비가 낮은 경우 MUSIC이 MinNorm보다 우월한 성능을 보인다.

• Parasites, Hosts and Diseases
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• 제42권1호
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• pp.1-6
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• 2004

The present study was undertaken to investigate the infection status of Cryptosporidium parvum in the villagers and the reservoir hosts in several rural areas in Korea. A total 5,262 fecal samples were collected from the inhabitants residing at Gangwon-do, Chungcheongbuk-do, Jeollanam-do, and Gyeongsangnam-do between the dates of September, 2001 to June, 2002. In addition, 1,453 fecal samples were collected from livestock reared in Gokseong-gun, Jeollanam-do and Chungju-si, Chungcheongbuk-do. All the fecal smears were prepared by formalin-ether sedimentation, and examined by light microscopy after modified acid-fast staining. The overall positive rate of human cryptosporidiosis was 3.3%. Gokseong-gun, Jeollanam-do showed a 8.2% positive rate and appeared as the highest endemic area among the surveyed areas. Haman-gun, Gyeongsangnam-do showed a 0.4% positive rate and was the lowest endemic area. The positive rate of livestock infection in Gokseong-gun, Jeollanam-do was 94%, which was more than ten times higher than that of Chungju-si, Chungcheongbuk-do (9.3%). From these results, it was revealed that cryptosporidiosis was an endemic disease in some rural areas of Korea, and the livestock could be an important source of human infection.