지구온난화에 따른 제주도 근해의 해수면 상승과 제주도 동부 지역 지하수의 염수대 변화

김경호,신지연,고은희,고기원,이강근,Kim, Kyung-Ho,Shin, Ji-Youn,Koh, Eun-Heui,Koh, Gi-Won,Lee, Kang-Kun 한국지하수토양환경학회 2009 지하수토양환경 Vol.14 No.3

Groundwater is the main water resource in Jeju Island because storage of surface water in reservoir is difficult in the island due to the permeable volcanic rocks. Because of this reason, the groundwater is expected to be very vulnerable to seawater intrusion by global warming, which will cause sea level rise. The long term change of mean sea level around the Korean Peninsula including Jeju Island was analyzed for this study. The sea level rise over the past 40 years was estimated to be of $2.16\;{\pm}\;1.71\;mm/yr$ around the Korean Peninsula. However, the rising trend around the eastern part of Jeju Island was more remarkable. In addition, the groundwater/seawater intrusion monitoring network operated by the Jeju Special Self-Governing Province shows that seawater intrusion becomes more prominent during dry 4-5 months in a year when the sea level increases. This implies that the fresh groundwater lens in the eastern part of Jeju Island is influenced by the sea level rise due to global warming in the long term scale. 제주도는 투수성이 좋은 화산암류로 형성이 되어 지표수의 발달이 빈약하므로 수원의 대부분을 지하수에 의존하고 있다. 따라서 지구 온난화로 인한 해수면 상승이 발생하여 지하수로의 해수 침투가 발생할 경우 매우 심각한 문제에 봉착할 수 있는 취약성을 지녔다. 본 연구에서는 장기 조위 관측 자료를 토대로 한반도 주변과 제주도 근해의 장기적인 해수면 변화를 분석하였다. 그 결과, 최근 40년 간 한반도 주변에서 해수면이 $2.16\;{\pm}\;1.71\;mm/yr$의 속도로 뚜렷한 상승 양상을 보였으며 제주도 해안에서는 더욱 빠른 속도로 해수면이 상승해 왔음을 알 수 있었다. 또한 제주특별자치도의 지하수/해수침투관측망의 지하수 관측 자료를 통하여 갈수기 중 해수면이 연주기적으로 상승하는 4-5개월 정도의 시기 동안 해수면의 상승에 따라 염수대가 육지 쪽으로 확장하여 침투하고 있는 것을 관측할 수 있었다. 이를 통하여 제주도 동부 지역이 장기적으로 해수면의 상승에 따라 염수대가 육지 쪽으로 확장하여 침투하였음을 간접적으로 보였다. 이는 지구 온난화에 의한 해수면의 상승이 그 동안 관찰되어 왔던 제주도 동부 지역의 해수 침투현상의 한 원인이 될 수 있음을 제시하고 있다.

III급 부정교합의 조기치료

김경호,Kim, Gyeong-Ho 대한치과의사협회 1999 대한치과의사협회지 Vol.37 No.1

Debonding

김경호,백형선,Kim, Gyeong-Ho,Baek, Hyeong-Seon 대한치과의사협회 1992 대한치과의사협회지 Vol.30 No.5

핵연료 봉의 마찰변태구조 관찰과 프레팅 마멸 특성

김경호,이민구,이창규,위명용,김흥회,Kim, Kyeong-Ho,Lee, Min-Ku,Rhee, Chang-Kyu,Wey, Myeong-Yong,Kim, Whung-Whoe 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.12

In this research, fretting tests were conducted in air to investigate the wear characteristics of fuel cladding materials with the fretting parameters such as normal load, slip amplitude, frequency and the number of cycles. A high frequency fretting wear tester was designed for this experiment by KAERI. After the experiments, the wear volume and the shape of wear contour were measured by the surface roughness tester. Tribologically transformed structures(TTS) were analysed by means of optical and scanning electron microscopes to identify the main wear mechanisms. The results of this study showed that the wear volume were increased with increasing slip amplitude, and the shape of wear contour was transformed V-type to W-type. Also, it was found that the critical slip amplitude was 168${\mu}{\textrm}{m}$. These phenomena mean that wear mechanism transformed partial slip to gross slip to accelerate wear volume. The wear depth increased with an increase of friction coefficient due to increase of normal load and frequency. The fretting wear mechanisms were believed that, after adhesion and surface plastic deformation occurred by relative sliding motion on the contact between two specimens, TTS creation was induced by surface strain hardening and wear debris were detached from the contact surface which were produced by the micro crack propagation and creation.

성공과 리더십-위기를 성공의 기회로 바꾸는 10가지 방법

김경호,Kim, Gyeong-Ho 대한산업안전협회 2008 안전기술 Vol.121 No.-

고속액체크로마토그래피에 의한 알로에 제제 중의 알로에신의 정량

김경호,김현주,박정일,신영근,Kim, Kyeong-Ho,Kim, Hyun-Ju,Park, Jeong-Hill,Shin, Young-Geun 대한약학회 1996 약학회지 Vol.40 No.2

The contents of aloesin in aloe preparations were determined by HPLC. Aloesin was extracted 3 times with ethanol for 30 minutes. The ethanol extract was concentrated and suspend ed in saturated NaCl aqueous solution and successively partitioned with dichloromethane, n-butanol. Prepared samples were analyzed by HPLC on a reverse column(Inertsil ODS-2). In assay, internal standard was a puerarin and regression of calibration curve was 0.998. Recoveries of aloesin added to aloe preparation were 98~123(%).

황반부 망막전막 환자에서 내경계막 제거 후 발생한 시야 결손

김경호,이지웅,이지은,엄부섭,Kyong Ho Kim,Ji Woong Lee,Ji Eun Lee,Boo Sup Oum 대한안과학회 2011 대한안과학회지 Vol.52 No.3

Purpose: To report a case of visual field defect developed after internal limiting membrane (ILM) peeling in a patient with macular epiretinal membrane (ERM). Case summary: A 33-year-old female without a history of specific diseases presented with a gradually decreased visual acuity in the right eye for 3 years. The patient was diagnosed as having macular ERM and underwent vitrectomy. During ILM peeling, retinal hemorrhage occurred in the superior region of macula, which spontaneously disappeared 2 weeks after surgery. Transmission electron microscopy showed Müller cell end feet with damaged appearance adherent to the ILM. At 3 months after surgery, the patient developed retinal nerve fiber layer (RNFL) defect in the area where the spot retinal hemorrhage had occurred. Optical coherence tomography showed focal RNFL thinning in the superotemporal region. The automated perimetry revealed corresponding inferior nasal step and scotomas in the right eye. Intraocular pressure was normal throughout the follow-up period and there was no evidence of glaucomatous optic disc change. Conclusions: The results obtained from the patient in the present study indicated that visual field defect may be the result of a mechanical damage to the RNFL during ILM peeling. J Korean Ophthalmol Soc 2011;52(3):378-384

유전 알고리듬을 이용한 매니퓰레이터 조인트의 마찰력 규명 및 실험적 검증

김경호,박윤식,Kim, Gyeong-Ho,Park, Yun-Sik 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.6

Like many other mechanical dynamic systems, flexible manipulator systems experience stiction or sticking friction, which may cause input-dependent instabilities. Manipulator performance can be enha nced by identifying friction but it is hard and expensive to measure friction by direct and precise sensing of contact displacements and forces. This study addresses the problem of identifying flexible manipulator joint friction. A dynamic model of a two-link flexible manipulator based upon finite element and Lagrange's method is constructed. The dynamic model includes the effects of joint compliances and actuator dynamics. Friction is also incorporated in the dynamic model to account for stick-slip at the joints. Next, the friction parameters are to be determined. The identification problem is posed as an optimization problem to be solved using nonlinear programming methods. A genetic algorithm is used to increase the convergence rate and the chances of finding the global optimum. The identified friction parameters are experimentally verified and it is expected that the identification technique is applicable to a system parameter identification problem associated with a wide class of nonlinear systems.

기증자 이야기

김경호,김지환,박희경,임우택,Kim, Gyeong-Ho,Kim, Ji-Hwan,Park, Hui-Gyeong,Im, U-Taek 한국조혈모세포은행협회 2005 나누는사람들 Vol.30 No.-

Effect of Niobium and Tin on Mechanical Properties of Zirconium Alloys

김경호,최병권,백종혁,김선재,정용환,Kim, Gyeong-Ho,Choe, Byeong-Gwon,Baek, Jong-Hyeok,Kim, Seon-Jae,Jeong, Yong-Hwan Materials Research Society of Korea 1999 한국재료학회지 Vol.9 No.2

2원계 (Zr-xNb, Zr-xSnl 와 3원계 (Zr-O.8Sn-xNb, Zr-O.4Nb-xSnl Zr합금의 기계적 특성에 미치는 Nb와 Sn의 영향올 조사하기 위하여 인장시험 빛 마세조직 분석을 실시하였다. Nb와 Sn량이 많이 첨가될수록 2원계와 3원계 합금의 강도는 정진적으로 증가하는 경향을 보이는데, Nb와 Sn이 고용도 이상으로 첨가될 때 강도중가는 더욱 두드러진 것으로 냐타났다. 강도 증가현상을 고용강화, 석출강화, 결정립 미세화에 의한 강화, 집합조직에 의한 강화효과 관정에서 분석한 결과, 고용강화 효과가 가장 두드러지며 Nb와 Sn이 고용도 이상에서는 석출강화가 강도에 기여하는 것으로 냐타났다. 합금원소 첨가에 따른 결정립미세화도 강도에 약간은 영향을 미치는 것으로 사료된다. 그러나 집합조직은 합금원소 변화에 따라서 거의 변화가 없는 것으로 냐타났으므로 집합조직은 강도증가에 기여하지 않는 것으로 생각된다. To investigate the effect of niobium and tin on the mechanical properties of zirconium alloys, the tensile test and the microstructural analysis were performed on the Zr-based binary(Zr-xNb, Zr-xSn) and ternary(Zr-0.8Sn-xNb, Zr-0.4Nb-xSn) alloys. As the content of Nb or Sn element increased, the strengths of the Zr-based alloys tended to gradually increase. The increase of mechanical strength was remarkable strength was remarkable in the range more than the solubility of Nb and Sn. The strengthening effects were discussed on the basis of the solid solution hardening, the precipitate hardening, the grain size effect, and the texture effect. The mechanical strength is mainly controlled by the solid solution hardening and additionally by the precipitate hardening in the content more than solubility limit of Nb and Sn. The grain refinement also has a slight effect on the strength of the zirconium alloys with the addition of Nb and Sn. However, the texture effect can be excluded due to the same Kearns number regardless of the content of alloying elements.