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이봉직(李奉稙) 아동문학평론사 2022 兒童文學評論 Vol.47 No.2

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이봉직(李奉稙) 아동문학평론사 2016 兒童文學評論 Vol.41 No.1

연약지반의 침하특성을 고려한 샌드매트의 실용적 설계를 위한 고찰

이봉직,권영철,이종규 한국지반환경공학회 2007 한국지반환경공학회논문집 Vol.8 No.5

The practical design method on sandmat uses a drain length, rate of consolidation settlement and permeability of sand as a major design factors. And, on the basis of this design process, it has been installed beneath the embankment with same thickness. However, the possibility the underestimation on the thickness of sandmat and the delayed drain have been pointed out by several authors caused by a differential settlement at the center and the end of embankment. In this study, therefore, the effect of the differential settlement on the thickness of sandmat and delayed drain through the numerical analysis of embankment was analyzed. As a result, a substantial sandmat thickness becomes small and the possibility of the delayed drain can be certified because of the development of differential settlement at the center and ends of embankment. As a countermeasure to overcome this problem, the applicability of the mound type sandmat was also investigated by the numerical method. It can be concluded that it maintains the designated substantial sandmat thickness throughout consolidation process, and is useful method to maintain the drain capacity. Especially, the mound type sandmat is effective method for a construction site where can cause a differential settlement such as embankment. Furthermore, it has to be designed on the basis of the accurate prediction of consolidation settlement as well as rate of consolidation settlement, drain length and permeability of sand. 현재 실무에서 사용되고 있는 샌드매트의 설계법에서는 주로 수평배수층의 배수거리, 침하속도, 투수성 등을 설계 인자로 사용하고 있으며, 현장 시공 시에는 성토체 하부에 동일한 두께로 시공하고 있다. 그러나 하부 연약지반의 변형에 따라 성토 중앙부와 양단에서 부등침하가 발생하게 되어 샌드매트 두께산정에 있어 과소평가될 가능성과 배수지연을 유발할 우려가 있음이 지적되어왔다. 본 연구에서는 연약지반의 변형으로 인해 생기는 부등침하의 발생이 배수지연 및 샌드매트의 두께산정에 어떠한 영향을 미칠 수 있는지 여부를 수치해석을 통해 분석하였다. 해석 결과 부등침하로 인하여 실질 유로두께의 감소를 확인할 수 있었으며, 새로운 위치수두의 차가 발생하여 배수지연 현상을 유발할 가능성이 있음이 확인되었다. 이에 대한 대응책으로 본 연구에서는 사전에 부등침하를 예측하여 성토 중앙부의 샌드매트 두께를 증가시킨 마운드형 샌드매트의 적용성에 대하여 검토하였으며, 압밀의 진행에 따라 변형이 크게 발생하여도 소정의 실질 유로두께를 유지하고 있음을 확인하였다. 특히, 마운드형 샌드매트는 연약지반 성토와 같이 변형의 분포가 위치에 따라 다른 경우의 건설공사에 매우 유효하리라 판단하며, 경제적이고 합리적인 수평배수재로서 적용이 가능할 것으로 판단되었다. 또한, 마운드형 샌드매트의 설계를 위해서는 성토단계별로 압밀속도, 배수거리나 투수성뿐만 아니라 연약지반의 침하특성을 정확하게 예측하는 것이 필수적이라고 사료된다.

치과진료 중 발생 가능한 측두하악장애의 유형과 진단

서봉직,이경은 대한치과의사협회 2006 대한치과의사협회지 Vol.44 No.11

양단정착형 쏘일네일링의 인발특성

이봉직,김조순,이종규 한국지반환경공학회 2007 한국지반환경공학회논문집 Vol.8 No.4

In this study, several pullout tests were carried out under various field conditions to evaluate the pullout force of the end fixed nails. Pullout resistance force, displacement and friction force between the grouting and nail were measured in end fixed nails installed in soft rock, weathered rock and weathered soil. Furthermore, the field test were also carried out under the same condition using the conventional type nails. Based on the test results, it is concluded that the end fixed nails showed larger ultimate resistance force compared with conventional types nails, approximately two times in weathered soil and 1.6 times of weathered rock, respectively. The skin friction is also increased in end fixed type about 1.8~3.0 times. Finally, it is concluded in the base of the force transfer properties that using the end fixed nails could decrease the displacement and show a uniform resistance in entire length of nails. 양단정착형 네일의 인발력을 평가하기 위하여 여러 조건에 대한 현장실험을 실시하였다. 현장인발시험은 연암, 풍화암 및 토사지반를 대상으로 인발력, 변위 및 그라우트와 네일의 마찰력 등을 측정하였으며, 이의 결과를 동일 조건에서 실시된 일반네일의 시험결과와 비교하였다. 시험결과 한계인발력은 양단정착형네일이 일반네일에 비하여 토사지반에서는 2배 이상, 풍화암에서는 약 1.6배 큰 것으로 분석되었으며, 단위길이당 주면마찰력도 양단정착형네일이 일반네일에 비하여 약 1.8~3배정도 증대되는 효과가 있는 것으로 분석되었다. 또한, 네일종류에 따른 하중전이특성 분석결과 양단정착형네일의 경우에는 변위는 작고, 네일 전 길이에 걸쳐 하중을 균등하게 부담함을 알 수 있다.

Endoscopic Versus Traditional Craniofacial Resection for Patients with Sinonasal Tumors Involving the Anterior Skull Base

김봉직,김대우,김시환,한두희,김동영,이재서,이철희 대한이비인후과학회 2008 Clinical and Experimental Otorhinolaryngology Vol.1 No.3

Objectives. With the advent of microdebriders and image guidance systems, endoscope-assisted surgery is now more widely used for the treatment of tumors involving the base of the skull. The aim of this study was to analyze the clinical features of tumors involving the anterior skull base and to evaluate the treatment outcomes according to the surgical approach, which included the traditional craniofacial resection (TCFR) and the endoscopic craniofacial resection with craniotomy (ECFR). Methods. Forty-six patients who underwent craniofacial resection from 1989 through 2006 at Seoul National University Hospital and Seoul National University Bundang Hospital were included in this study. Demographics, histology, surgical management, surgical outcomes, complications, and morbidity were analyzed. Results. The number of malignant and benign lesions was 40 and 6 cases respectively. The most common diagnosis was olfactory neuroblastoma occurring in 41% of the cases followed by squamous cell carcinoma and malignant melanoma. Thirty-six patients underwent TCFR, while ECFR was performed with or without adjunctive chemotherapy or radiotherapy in 10 patients. The overall five-year survival rate for patients with malignant tumors of the anterior skull base was 47.4%. Out of 19 patients with olfactory neuroblastomas, 10 patients had TCFR and six among them died of their disease. Nine patients underwent ECFR, and none of them died of their disease. The ECFR group had lower morbidity and cosmetic deformity than did the TCFR group. Conclusion. The ECFR may be considered as an alternative option for the treatment of selected tumors with anterior skull base invasion. This approach offers the advantages of avoiding facial incisions with comparable treatment results. Objectives. With the advent of microdebriders and image guidance systems, endoscope-assisted surgery is now more widely used for the treatment of tumors involving the base of the skull. The aim of this study was to analyze the clinical features of tumors involving the anterior skull base and to evaluate the treatment outcomes according to the surgical approach, which included the traditional craniofacial resection (TCFR) and the endoscopic craniofacial resection with craniotomy (ECFR). Methods. Forty-six patients who underwent craniofacial resection from 1989 through 2006 at Seoul National University Hospital and Seoul National University Bundang Hospital were included in this study. Demographics, histology, surgical management, surgical outcomes, complications, and morbidity were analyzed. Results. The number of malignant and benign lesions was 40 and 6 cases respectively. The most common diagnosis was olfactory neuroblastoma occurring in 41% of the cases followed by squamous cell carcinoma and malignant melanoma. Thirty-six patients underwent TCFR, while ECFR was performed with or without adjunctive chemotherapy or radiotherapy in 10 patients. The overall five-year survival rate for patients with malignant tumors of the anterior skull base was 47.4%. Out of 19 patients with olfactory neuroblastomas, 10 patients had TCFR and six among them died of their disease. Nine patients underwent ECFR, and none of them died of their disease. The ECFR group had lower morbidity and cosmetic deformity than did the TCFR group. Conclusion. The ECFR may be considered as an alternative option for the treatment of selected tumors with anterior skull base invasion. This approach offers the advantages of avoiding facial incisions with comparable treatment results.

실시간 웹서버 시스템을 위한 통합 스케줄링 방안

강봉직,정석용,이현숙,최경희,정기현,유해영,Kang, Bong-Jik,Jung, Suk-Yong,Lee, Hyun-Suk,Choe, Gyeong-Hui,Jeong, Gi-Hyeon,Yu, Hae-Yeong 대한전자공학회 2002 電子工學會論文誌-CI (Computer and Information) Vol.39 No.6

본 논문에서는 웹서버를 탑재한 내장형 시스템에서 실시간 속성을 만족시킬 수 있는 스케줄링 기법을 제안한다. 내장형 시스템에 웹서버를 응용프로그램의 형태로 탑재하는 경우 운영체제와 웹서버간의 이원화된 스케줄링 때문에 우선 순위 역전 현상이 발생하여 실시간 속성을 만족시키지 못한다. 이에 본 논문에서는 웹서버의 일부 스케줄링 기능을 운영체제의 스케줄러와 통합 내장시켜 일관된 스케줄링 방법을 제공한다. 제안된 스케줄링 기법을 실험용 내장형 시스템에 적용한 결과, 웹서버를 일반 태스크로 구현한 경우와 달리 우선 순위 역전 현상이 발생하지 않았다. 또한 우선 순위에 따라 태스크별 응답 시간이 시스템 부하에 관계없이 일정하여 제안된 스케줄링 기법이 실시간 내장형 웹서버 시스템에 적합하다. This paper proposes an integrated scheduling mechanism for embedded system with real-time web server to meet the characteristics of real time task. The proposed scheduling mechanism may solve the so-called priority inversion problem in scheduling between urgent web requests and tasks with low priorities. The priority inversion problem happens because of operating two independent schedulers, web scheduler and operating system scheduler in a system without considering the requirements of each other. In the proposed mechanism, two schedulers are integrated in an operating system and the integrated scheduler schedules tasks for urgent web requests with real time characteristics and other application tasks together. Since all tasks are scheduled by one unified scheduler that knows the characteristics of tasks, the tasks are scheduled with their absolute priorities and thus the priority inversion problem can be eliminated. The performance is measured on a prototype embedded system with the proposed algorithm.

스트레스하에서 구강안면동통 경험이 심리적 증상에 미치는 영향에 관한 연구

서봉직,Suh, Bong-Jik 대한안면통증구강내과학회 1999 Journal of Oral Medicine and Pain Vol.24 No.2

The author studied the prevalence and sites of orofacial pain during the latest 6 months, and psychologic symptoms under the emotional stress through SCL-90-R in thirty-five dental students(nineteen men and sixteen women) of school of Dentistry, Chonbuk National University. 26 students(74.3%), 12 men and 14 women, experienced the orofacial pain; headache, toothache, facial & buccal pain, TMJ pain and intraoral pain were occurred in 51.4%, 37.1%, 25.7%, 17.1% and 17.1% respectively. In psychological scores in before-, during- and after examination, there was no significant difference between men and women. On the other hand, when these scores were compared each other in one group with orofacial pain experience and the other group without pain experience, the former showed significantly higher values in somatization, depression, hostility, and paranoid ideation dimension before examination, interpersonal sensitivity and anxiety dimension during examination, and somatization dimension after examination than those of the later group(P<0.05). The changes of psychologic symptoms in before-, during-, and after examination were observed in one group with pain experience and the other group without pain experience, respectively; in the former group the significantly higher values of anxiety dimension in during examination than after examination, and the significantly higher values of interpersonal sensitivity dimension in before examination than after examination(P<0.05) were evaluated.

점성토 지반에서의 다중 헬리컬 앵커의 인발 특성

이봉직,이준대,이종규 한국산업안전학회 1997 한국안전학회지 Vol.12 No.4

Helical anchors are foundation structure that designed to resist uplift loads are installed by applying in load to shaft while rotating it into the ground. These can be a cost effective means of proving tension anchorage for foundation where soil conditions permit their installation because of ease of installation. At present time, tapered helical anchors are commonly used to carry uplift loads. The uplift capacity includes the following factors : the height of overburden above the top helix, the resistant along a cylinder, the weight of the soil in the cylinder and suction force. In order to make clear behavior chacteristics of helical anchors with pullout, model tests were conducted with respect to various embedment depth, space of helix, shape of helix. Based on the experimental study, the following conclusions are drawn. 1) The uplift capacity of multi helical anchors increase with embedment ratio of anchors The increase is smooth after critical uplift capacity. 2) Critical breakout factors and critical embedment ratio of multi helical anchor exist 7∼8, 4∼6 respectively 3) Variation of uplift capacity with helix spaces show down after S/D=5. 4) Critical breakout factors of helical anchor in the laboratory test are similar to Das's theory.

점토의 변형률 속도 의존성을 고려한 비선형 유한변형 압밀해석

이봉직(Lee Bongjik),이흥길(Lee Heunggil),권영철(Kwon Youngcheul) 한국지반환경공학회 2008 한국지반환경공학회논문집 Vol.9 No.6

재료적 비선형성과 합리적인 좌표계의 도입이 압밀문제에 있어 중요한 자리를 점한다는 인식에서 비선형 유한변형압밀이론이 제안되어 왔으나 너무 어려운 매개변수 설정 등의 문제점에 의해 일반적인 압밀해석에서 널리 사용되고 있지는 못하다. 본 연구에서는 구분선형(piecewise-linear) 압밀이론을 이용하여 점토의 변형률 속도 의존성을 고려한 압밀해석이 가능한 해석법을 제시하는 것을 목표로 하였다. 특히 유사한 방법에서 큰 문제가 되어 왔던 압축곡선의 유일성을 해결할 수 있는 방안으로 기준곡선을 이용하는 방안을 도입하였다. 개발된 해석법의 검증을 위해 실시된 일련의 과정을 통해 모델의 적용성을 일부 확인하였으며 향후 제한적인 실내실험결과에서 확장하여 실제 압밀문제에 대한 적용성 확인 등의 연구가 수행되어야 할 것으로 판단하고 있다. In recent years, finite strain consolidation theories including a mechanical nonlinearity and a reasonable coordinate system have been proposed and used in educations and practical consolidation problems. However, despite their reasonable ability to predict the consolidation behavior, their failure in the field can be attributed to the complexity of estimating and selecting proper parameters for simulating the consolidation phenomenon. In this study, therefore, the application of a piecewise-linear method was proposed to solve such problems including the assumption of the uniqueness in compressibility. Especially, the concept of reference curve was introduced to define the effect of strain rate dependency of clay. The applicability of the methodology is verified by several tests. It was found that the proposed method is applicable in restrictive ranges of study carried out in the laboratory. Finally it is expected that the verification in field consolidation problem has to be carried out through future study.