• Journal of Communications and Networks
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• 제10권3호
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• pp.338-350
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• 2008

The differentiated services (DiffServ) is proposed to provide packet level service differentiations in a scalable manner. To provide an end-to-end service differentiation to users having a connection over multiple domains, as well as a flow marker, an intermediate marker is necessary at the edge routers, and it should not be operated at a flow level due to a scalability problem. Due to this operation requirement, the intermediate marker has a fairness problem among the transmission control protocol (TCP) flows since TCP flows have intrinsically unfair throughputs due to the TCP's congestion control algorithm. Moreover, it is very difficult to resolve this problem without individual flow state information such as round trip time (RTT) and sending rate of each flow. In this paper, to resolve this TCP fairness problem of an intermediate marker, we propose a fair scalable marker (FSM) as an intermediate marker which works with a source flow three color marker (sf-TCM) operating as a host source marker. The proposed fair scalable marker improves the fairness among the TCP flows with different RTTs without per-flow management. Through the simulations, we show that the FSM can improve TCP fairness as well as link utilization in multiple domain DiffServ networks.

• Earthquakes and Structures
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• 제11권3호
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• pp.505-516
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• 2016

This paper evaluates the scaling of ground motions recorded from nine intermediate-depth earthquakes produced in the Vrancea seismic zone in Romania. The considered ground motion database consists of 363 horizontal recordings obtained on soil classes B and C (according to Eurocode 8). An analysis of the inter- and intra-event spectral accelerations is performed in order to gain information regarding the magnitude and distance scaling of the Vrancea ground motions. The analyses reveal a significant influence of the earthquake magnitude and focal depth on the distance scaling and different magnitude and distance scaling for the two soil classes. A linear magnitude and distance scaling is inferred from the results for the range of magnitudes $5.2{\leq}M_W{\leq}7.1$. The results obtained are checked through stochastic simulations and the influence of the stress drop and kappa values on the ground motion levels is assessed. In addition, five ground motion models which were tested in other studies using recordings from Vrancea earthquakes are analyzed in order to evaluate their corresponding host stress drop and kappa. The results show generally a direct connection between the host kappa values and the host stress drop values. Moreover, all the ground motion models depict magnitude dependent host kappa and stress drop levels.

• Parasites, Hosts and Diseases
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• 제24권2호
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• pp.194-200
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• 1986

1986년 5월부터 동년 10월까지 폐흡충 침윤지로 알려진 경북 울진군을 관류하는 남대천, 광천, 왕피천에서 가재의 분포상을 조사한 다음 가재에서의 폐흡충 피낭유충 기생상을 조사하였다. 가재의 서식밀도는 한사람이 한시간에 잡을수 있는 가재의 평균수로 표시하였으며, 이번 조사에서는 최소 1마리, 최고 13마리, 평균 4마리를 채집 할 수 있었다. 가재에서의 폐흡충 피낭유충 검출률은 총 피검가재 817마리중 127마리 (15.5%)였으며, 지역별로는 두천계곡에서 25.1%로 가장 높았다. 가재 체부위별 검출상은 감염가재 127마리에서 총 219개의 피낭유충을 검출하였으며, 이중 두흉부(60.7%), 아가미(37.4%), 간(1.8%)순으로 검출 할 수 있었으며, 감염가재 1마리당 평균 유출수는 1.7개 이었다. 이상의 성적으로 미루어 보아 경북 울진군 남대천, 광천, 왕피천 유역은 아직도 폐흡충 침윤지로 남아 있음을 알았다.

• Parasites, Hosts and Diseases
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• 제60권2호
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• pp.79-96
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• 2022

The infection nature of Clonorchis sinensis metacercariae (CsMc) in freshwater fish hosts is closely related to the transmission of human clonorchiasis. This article reviewed the infection characteristics of CsMc in freshwater fish in the Republic of Korea (Korea). The status of CsMc infection was examined in a total of 17,792 cyprinid fish of 49 species in 9 water systems, which included Hantan-/Imjin-gang, Han-gang, Geum-gang, Mangyeong-gang, Yeongsan-gang, Tamjin-gang, Seomjin-gang, Nakdong-gang, and streams in the east coastal areas from 2010 to 2020. The infection status of CsMc was examined according to cyprinid fish species and water systems, after which analyzed by endemicity and susceptibility index. The high endemicity was shown in the cyprinid fish from 3 regions (6.1%) in the upper reaches of Nakdong-gang, such as Banbyeon-cheon (stream), Yongjeon-cheon, and Wi-cheon. The moderate levels were observed in fishes from 8 regions (16.3%), and low endemicity was shown in fishes from 20 regions (40.8%). No CsMc were detected in fish from 18 regions (36.7%). The susceptibility of CsMc in index fish, Puntungia herzi, was found to be a reliable index without examination of other fish species. CsMc infection rates were closely related to subfamily groups in the cyprinid fish hosts in a highly endemic area. In Korea, a total of 58 fish species in 10 families has been listed as the second intermediate hosts for C. sinensis. This review provides several novel features of CsMc infection and clarifies the species of second intermediate freshwater fish host in Korea.

• Parasites, Hosts and Diseases
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• 제62권1호
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• pp.1-29
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• 2024

This article analyzed the infection characteristics of metacercariae of Metagonimus spp. (MsMc) in fish from 9 major water systems in Korea. A total of 19,568 fish in 87 species were examined over a period of 10 years (2011-2020). MsMc were detected in fish from all 44 survey areas in 9 water systems. Most of the surveyed sites showed very low and low infection levels (66.7%), while 33.3% of the areas, such as Tamjin-gang and Seomjin-gang, revealed moderate and high infection levels. High endemicity depends on the abundance of susceptible fish species, especially sweet smelt (Plecoglosus altivelis). The susceptibility index (SI) with MsMc in index fish, Zacco spp., was very low and low levels in 62.0%, moderate in 28.0%, and high in 10.0% regions. The SI was highest in the following order: Yeongam-cheon (283.8), Hoeng-cheon (192.3), Togyo-jeosuji (131.2), Deokcheon-gang (119.1), and Joyang-gang (106.3). The recent infection status of MsMc in P. altivelis was analyzed by the survey localities. In addition, except for P. altivelis, 9 fish species were highly infected with MsMc in some survey areas, including Zacco platypus, Z. koreanus, Z. temminckii, Opsariichthys uncirostris, Rhynchocypris oxycephalus, Carassius auratus, Acheilognathus rhombeus, Onchorhynchus masou, and Tribolodon hakonensis. In Korea, 74 fish species (15 families) are collectively listed as second intermediate hosts of Metagonimus spp. This review provides several novel characteristics of MsMc infection and clarifies the fish species of second intermediate host of Metagonimus spp. in this country.

• Parasites, Hosts and Diseases
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• 제28권3호
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• pp.175-182
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• 1990

경남 진주시의 뱀집에서 구입한 유혈목이(Rhabdophis tigrina)에서 Pharyngostomum cordatum의 피낭유충을 검출하였으며, 수집된 피낭유충을 마우스, 횐쥐, 햄스터, 오리, 개 및 고양이에 경구 감염시켰던 바, 고양이에서만 감염 후 5주에 성충이 회수되었다. 피낭유충은 전단이 후단에 비해 조금 풍족하였으며 복측으로 만곡되어 있었고 체내에는 원형 또는 타원형의 배설과립이 충만되어 있었다. 체장은 0.60∼0.85(평균 0.71)mm, 체폭은 0.42∼0.60(평균 0.49)mm이었으며 각 기관의 계측치 및 형태학적 특징이 P. cnrdatum과 일치하였다 고양이로부터 회수한 성충은 충체가 매우 육질성이 었으며 앞, 뒤 두 부분으로 나뉘어져 있었고 체잘은 1.41∼2.19mm(평균 1.74mm)이었다. 각 기관의 계측치 및 형태학적 특징이 기 보고된 Ciurea(1922), Cho and Lee (1951) 등의 결과와 일치하여 P. cerdatum(Diesing, 1850) Ciurea, 1922으로 동정하였다. 이상의 결과로 우리 나라에서 유혈목이가 P. cordatum의 제 2중간숙주(또는 paratenic host)로 작용하고 있음을 확인하였다.

• Parasites, Hosts and Diseases
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• 제62권1호
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• pp.85-97
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• 2024

This study aimed to describe the morphological and molecular characteristics of Paralecithodendrium longiforme (Digenea: Lecithodendriidae) adults and cercariae isolated in Thailand. Adult flukes were isolated from the Chinese pipistrelle bat (Hypsugo sp.), and cercariae were detected in the viviparid snail (Filopaludina martensi martensi) from Chiang Mai province. The morphological characteristics were observed and described using conventional methods, and the molecular characteristics with internal transcribed spacer 2 (ITS2) and 28S rDNA gene sequences. The adult flukes were fusiform, 0.84-0.98 mm in length, and 0.37-0.49 mm in width, and were distinguishable from other species by the presence of longitudinal uterine coils. The cercariae were nonvirgulate xiphidiocercariae, with the oral sucker bigger than the acetabulum, the tail without fin fold, a body size of 117.5-138.3×48.3-52.2 ㎛, and a tail size of 100.7-103.7×15.0-18.9 ㎛. Molecular studies revealed that the adults and cercariae shared 99.3% (ITS2) and 99.6% (28S rDNA) homology with each other. They were phylogenetically close to P. longiforme with an identity of 94.5% for ITS2 and 98.7% for 28S rDNA. This study provides new information on the natural definitive host and first intermediate host of P. longiforme in Thailand. The discovery of its cercarial stage in Filopaludina snails highlights the importance of monitoring the associated second intermediate host and prevention and control of this potentially zoonotic trematode.

• 한국수산과학회지
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• 제6권3_4호
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• pp.112-122
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• 1973

붕어와 금붕어에 기생하는 사상충, Philometroides carassii (Ishii, 1931)를 구제할 목적으로 1971년 4월부터 1972년 12월까지 당년어 붕어 200마리와 금붕어 150마리에 이 충의 유충을 여러가지 방법으로 감염시켜, 생활사를 규명하고 약물치료 실험을 하여 다음과 같은 결과를 얻었다. 1. 이 충은 Cyclops sp.가 중간숙주이며 이것의 복강에 침입한 유충은 3시간 이후에 감염력을 가졌다. 2. Cyclops sp.를 경유하지 않고 직접 먹힌 유충은 어체내에서 24시간내 장에서 소화되거나 배설되었다. 3. 중간숙주를 경유하여 어체의 장에 기생한 유충은 $1\~10$일후 복강속으로 침입하고, 여기서 성장하여 미성숙성충이 되었다. 붕어 복강속에서 기생하는 미성숙 성충은 $18\~20$개월 후 꼬리지느러미로 나와 성충이 되었다. 금붕어 복강속에 기생하는 미성숙 성충은 $7\~8$개월 후 꼬리지느러미로 나와 성충이 되었다. 4. 어체 복강속에 기생하는 미성숙 성중에서 본 종의 수컷을 최초로 발견했으며 암컷보다 대형이었다. 5. 성충에 대한 약물 치료효과는 기대할 수 없었고 성충에서 방출되는 유충에 대해 약욕 치료실험한 결과 dipterex가 가장 효과가 있었으며 4ppm으로 5일만에 대부분 폐사되었다.

• Parasites, Hosts and Diseases
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• 제38권1호
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• pp.1-7
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• 2000

In certain Asian countries, a third form of human Taenia, also known as the Asian Taenia, has been discovered. This Asian Taenia seems to be an intermediate between Taenia solium and T. saginata since in morphological terms it is similar to T. saginata, yet biologically, as it uses the same intermediate host (pigs) , it is more akin to T. solium. Taenia solium causes human cysticercosis, while T. saginata does not. It is not known whether the Asian taeniid is able to develop to the larval stage in humans or not. The arguments proposed by those authors who consider it unlikely that the Asian Taenia causes human cysticercosis are: (a) its molecular similarities with T. saginata: (b) the absence of cases of human cysticercosis in populations where the Asian adult is highly prevalent; and (c) the unsupporting results derived from an experimental infestation study. These three arguments are debated, although bearing in mind that at present there is still no clear scientific data to support that human cysticercosis can be caused by the Asian Taenia.

• Parasites, Hosts and Diseases
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• 제41권2호
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• pp.101-105
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• 2003

The metacercariae of Acanthotrema felis Sohn et at., 2003 (Digenea: Heterophyidae) were discovered in a species of the brackish water fish, Acanthogobius flavimanus, in the Republic of Korea. They were experimentally fed to kittens, and adult flukes were harvested 7 days later. The adults were morphologically characterized by the presence of a bipartite seminal vesicle, the ventral sucker associated with a ventrogenital sac enclosing 3 sclerites (2 long and pointed, and 1 short and thumb-like), and an unarmed gonotyl. The adult flukes were identified as A. felis Sohn et al., 2003, and the brackish water fish A. flavimanus has been verified as one of its second intermediate hosts.