다중 이동통신 사업자의 LTE 망을 활용한 Multipath TCP 성능 평가

김응협,서원경,조유제 한국통신학회 2023 韓國通信學會論文誌 Vol.48 No.5

인터넷 상에서 이용되는 콘텐츠들이 다양해지고 품질이 높아지면서 요구되는 네트워크 대역폭이 급증하였다. IETF에서는 전송계층 표준 프로토콜인 MPTCP (Multipath TCP)를 제안하며, 다중 인터페이스 기반의 여러 서브플로우를 하나로 aggregation하여 높은 대역폭의 서비스를 지원하고 있다. 따라서 MPTCP 기능을 가지고 있는 장비를 활용하여 WiFi/LTE와 같은 이기종 네트워크 또는 여러 사업자의 LTE 망을 aggregation하면 사용자에게 더높은 품질의 서비스를 제공할 수 있다. 하지만, 인터넷에 존재하는 모든 장비에 MPTCP 기능을 추가하는데 어려움이 있어 전송 경로 상의 MPTCP 프록시를 활용한 다중 경로 aggregation 기술들이 연구되고 있다. 본 논문에서는 네트워크 처리량을 높이기 위해 MPTCP라우터 및 MPTCP프록시를 활용하여 KT와 SKT의 LTE 사업자 망을aggregation하였고 실제 환경에서 성능개선을 위한 테스트를 수행하였다. 또한 기존에 제안된 MPTCP 스케줄러및 혼잡제어 알고리즘을 LTE 환경에 적용하고 단일 LTE 사업자 망과 다중 LTE 사업자 망에서의 성능을 비교분석하였다.

Analysis of Risk Factors for Myringosclerosis Formation after Ventilation Tube Insertion

김응협,박기완,이승훈,김봉직,박용호 대한의학회 2020 Journal of Korean medical science Vol.35 No.13

Background: This study examined possible risk factors for myringosclerosis formation after ventilation tube insertion (VTI). Methods: A retrospective study was performed in a single tertiary referral center. A total of 582 patients who underwent VTI were enrolled in this study. Patients were divided into two groups based on the presence or absence of myringosclerosis: MS+ and MS−. Characteristics of patients were collected through medical chart review; these included age, gender, nature and duration of effusion, type of ventilation tube (VT), duration and frequency of VTI, incidence of post-VTI infection, incidence of intraoperative bleeding, and presence of postoperative perforation. Incidences of risk factors for myringosclerosis and the severity of myringosclerosis in association with possible risk factors were analyzed. Results: Myringosclerosis developed in 168 of 582 patients (28.9%) after VTI. Patients in the MS+ group had an older mean age than those in the MS− group. The rates of myringosclerosis were higher in patients with older age, serous otitis media, type 2 VT, post-VTI perforation, and frequent VTI. However, there were no differences in occurrence of myringosclerosis based on gender, duration of effusion, duration of VT placement, incidence of post-VTI infection, or incidence of intraoperative bleeding. The severity of myringosclerosis was associated with the duration of effusion and frequency of VTI. Conclusion: Older age, serous effusion, type 2 VT, presence of post-VTI perforation, and frequent VTI may be risk factors for myringosclerosis after VTI; the severity of myringosclerosis may vary based on the duration of effusion and frequency of VTI.

견갑거근에 발생한 섬유종증 1예

김응협,이건호,구본석,윤여훈 대한이비인후과학회 2009 대한이비인후과학회지 두경부외과학 Vol.52 No.12

Fibromatosis is a benign tumor arising from the musculoaponeurotic tissues of the body. The natural history of fibromatosis is slow, progressive growth with invasion of adjacent tissues but this tumor has no malignant or metastatic potential. Complete surgical excision is the mainstay of treatment. However, it is often difficult due to the complex anatomy, close proximity of vital structures in the head and neck region. Preoperative core needle biopsy and MR images can make it possible to diagnose preoperatively and outline the tumor extent, which are very important to treat patients with fibromatosis. In this report, a rare case of fibromatosis occurring in the levator scapulae muscle is presented with a review of literatures.

경부 자상 후 발생한 뇌척수액 누출 및 기뇌증 1예

김응협,이건호,구본석,윤여훈 대한이비인후과학회 2009 대한이비인후과학회지 두경부외과학 Vol.52 No.6

Pneumocephalus is defined as the presence of air within the cranial cavity. Trauma such as automobile accidents, motorcycle accidents, and missile injuries is the most common cause of pneumocephalus. There have previously been four reported cases of pneumocephalus following stab wounds to the neck in the English literature. We present an unusual case of pneumocephalus following a neck stab wound with a review of the literatures.

지연내성망 환경에서 확률 기반의 효율적인 메시지 전달 방안

김응협(Eung-Hyup Kim),남재충(Jae-Choong Nam),최재인(Jae-In Choi),김도희(Do-Hee Kim),조유제(You-Ze Cho) 한국통신학회 2013 한국통신학회 학술대회논문집 Vol.2013 No.11

Spray and Wait 라우팅을 위한 확률 기반의 메시지 전달 방안 및 버퍼 관리 방안

김응협 ( Eung-hyup Kim ),이명기 ( Myung-ki Lee ),조유제 ( You-ze Cho ) 한국정보처리학회 2016 정보처리학회논문지. 컴퓨터 및 통신시스템 Vol.5 No.7

Delay Tolerant Network(DTN)은 종단간 연결성이 보장되지 않는 환경에서 store-carry-forward 방식의 메시지 전달을 기본으로 하는 네트워크이다. DTN 환경에서 메시지 전달을 위한 라우팅 방안뿐만 아니라 버퍼 관리 정책 또한 전달률을 높이기 위한 중요한 요소이다. 본 논문에서는 기존 spray and wait 라우팅 방안의 메시지 전달률을 높이기 위한 확률 기반의 spray and wait 방안을 제안한다. 또한 버퍼 오버플로우 발생 시, L 값에 따라 메시지를 폐기하는 버퍼 관리방안도 제안하였다. 기존의 DTN 라우팅 방안인 Epidemic, PRoPHET, spray and wait 프로토콜과 성능을 비교하였으며 전달률 및 오버헤드의 성능이 개선되는 것을 시뮬레이션을 통해 확인하였다 Delay Tolerant Network (DTN) is a network that employed method of store-carry-forward in intermittently connected networks. In DTNs, routing and buffer management scheme are important to improve successful message delivery. This paper proposes an improve spray and wait routing protocol based on delivery probability to a destination. Also, a buffer management scheme is proposed to drop the queued messages according to the number of copies (L value). Simulation results show that the proposed method provides a better delivery ratio and lower communication overhead when compared to existing schemes such as Epidemic, PRoPHET and spray and wait

실험적으로 유도한 Gentamicin 전정독성 기니픽 모델에서 Memantine의 효과

박찬희,김응협,김수일,나기상,박용호 대한이비인후과학회 2010 대한이비인후과학회지 두경부외과학 Vol.53 No.2

Background and ObjectivesZZIn general, aminoglycosides are known to cause ototoxicity through the glutamate induced nitric oxide production. The N-methyl-D-aspartate (NMDA) related glutamate receptors have a pivotal role in aminoglycoside induced ototoxicity. Memantine is known as a safe NMDA antagonist and is also used in some neurologic insults, such as the Alzheimer disease. In this study, we observed the effect of memantine on gentamicin induced vestibulotoxicity in an animal model. Materials and MethodZZVestibulotoxicity was induced with intratympanic administration of gentamicin and memantine was injected intraperitoneally to a study group. Histomorphological studies for vestibule were performed via light and electron microscopy. Immunohistochemical studies were performed for iNOS, nitrotyrosine and apoptosis via TUNEL staining. ResultsZZThe numbers of hair cells were decreased significantly in the gentamicin group than in the gentamicin-memantine group. Increased immunoreactivities for iNOS and nitrotyrosine were observed in the gentamicin group than in the memantine-pretreated gentamicin group. TUNEL positive cells were more frequently observed in the gentamicin group than in the memantinepretreated gentamicin group. ConclusionZZThis result shows that memantine has a protection effect on gentamicin-induced vestibulotoxicity in an animal model. Korean J Otorhinolaryngol-Head Neck Surg 2010;53:77-83

만성 중이염 및 진주종성 중이염 환자에서 Biofilm의 형성

박용호,김응협,서성태,이상희,김진만,구본석,김용민,나기상 대한이비인후과학회 2009 대한이비인후과학회지 두경부외과학 Vol.52 No.2

Background and Objectives:In many chronic infections, bacteria are present as a form of biofilms. Recently, bacterial biofilm has been implicated in persistent or recurrent chronic otolaryngologic infections, because they are highly resistant to treatment with antimicrobial agents and capable of shedding individual bacteria to the surrounding tissues. In this study, we aimed to evaluate biofilm in chronic middle ear infections. Subjects and Method:A total of 85 cases with chronic middle ear infections were included in this study. Histomorphologic studies for middle ear granulations and cholesteatomas were performed using light and electron microscopy. Results:In middle ear granulations, about 33% of the cases showed the evidence of bacterial biofilm. In comparison, about 64% of the cases in cholesteatoma tissues have the evidences of bacterial biofilm. Conclusion:Biofilms are associated with chronic middle ear infection and they may play a role in the pathogenesis of refractory or persistent chronic middle ear infections.

포도상구균 장독소의 비점적이 알레르기비염 마우스에서 알레르기 염증반응에 미치는 영향

김용민,김응협,박찬희,윤여훈,김진만,나기상 대한이비인후과학회 2009 대한이비인후과학회지 두경부외과학 Vol.52 No.11

Background and Objectives The role of Staphylococcus aureus enterotoxin B (SEB) in allergic rhinitis remains controversial. We used a mouse model of airway allergy to determine the effects of nasal instillation of SEB on allergic inflammation. Materials and Method BALB/c mice were intranasally sensitized with compound of Aspergillus melleus proteinase (AMp) and ovalbumin (ova) in the presence (group 3) or absence of SEB (group 2). Control mice were intranasally sensitized with either phosphate buffered saline (PBS)(group 1) or SEB (group 4) alone. The production of serum antigen-specific antibodies and total IgE, and concentrations of cytokines including interleukin-4 (IL-4), IL-5, interferon-γ (IFN-γ) in nasal lavage fluid (NLF) and broncoalveolar lavage fluid (BALF) were compared among the groups. Pathologic studies for eosinophilic infiltrations in the nasal mucosa and peribronchial area were also conducted. Results Serum ova-specific immunoglobulin E (IgE) & immunoglobulin G1 (IgG1) were significantly increased in group 2 and 3 compared to group 1. The concentrations of IL-4 in BALF were significantly increased in group 2, 3, and 4 compared to group 1. The concentrations of IL-5 in BALF and NLF were significantly increased in Group 2, 3, and 4 compared to group 1. The concentrations of IFN-γ were significantly increased in group 3 and 4 compared to group 2 although there was no significant difference among the groups in NLF. Group 2 demonstrates increased infiltration of eosinophils in the nasal mucosa and peribronchial area compared to group 3 and 4. Conclusion These results suggest that the nasal exposure to SEB did not aggravate inflammation in allergic mice.

BALB/c 마우스에서 포도상구균 내독소의 비강내 점적이 비점막 및 기관지 점막에 미치는 영향

진성용,나기상,김응협,이건호,박영규,김용민 대한비과학회 2011 Journal of rhinology Vol.18 No.1

Background and Objectives:The effect of nasal exposure to staphylococcal enterotoxin in the pathogenesis of allergic rhinitis remains controversial. We sought to determine the effect of increasing doses of intranasally applied Staphylococcus aureus enterotoxin B (SEB) on the respiratory mucosa, especially the nasal mucosa. Materials and Methods:Nasal application of SEB was performed on four occasions (days 0-4-8-12) in unsensitized BALB/c mice. Control mice were intranasally treated with phosphate buffered saline (PBS), and 5 ng, 50 ng, 500 ng, and 5 μg of SEB was applied to the respective ex-perimental group. The concentrations of IL-4, IL-5, and IFN-γ in bronchoalveolar lavage fluid (BALF), nasal lavage fluid (NLF) and serum were compared among groups. Also, the counts of total inflammatory cells, macrophages, lymphocytes, neutrophils, eosinophils, and basophils in BALF and NLF were compared among the groups. Pathologic studies for inflammatory cell infiltration in the nasal mucosa and peribronchial area were conducted. Results:IL-4 and IFN-γ showed higher concen-trations with increasing stimulation dose of SEB in NLF and serum. The IL-5 concentration showed a tendency to increase in NLF and serum, but these changes were not statistically significant. Total inflammatory cell count, especially macrophage count, in BALF and NLF was higher with increasing stimulation dose of SEB. Infiltration of inflammatory cells into the nasal mu-cosa showed a tendency to increase in a dose-dependent manner. Conclusion:These results suggest that nasal exposure to SEB may induce Th1 and Th2 inflammatory responses in the respiratory mucosa, especially the nasal mucosa.