강재 품질에 따른 격자지보재의 성능평가

정혁상,신영완,송기일,신종호,Jung, Hyuk-Sang,Shin, Young-Wan,Song, Ki-Il,Shin, Jong-Ho 한국터널지하공간학회 2016 한국터널지하공간학회논문집 Vol.18 No.2

본 논문은 격자지보재의 규격자재와 비규격자재의 성능평가에 대한 내용을 다루었다. 격자보재는 강봉으로 제작된 아치형의 터널지보공을 말하며 터널 굴착시 지반의 변형을 최대로 억제하여 터널의 안정성을 확보하기 위하여 사용되어지는 지보재이다. 이런 격자지보재의 성능평가는 휨강도시험과 인장강도시험을 통해 평가할 수 있으며 터널표준시방서에서는 항복강도 500MPa 이상인 용접용 강재를 사용도록 규정하고 있다. 그러나 저품질의 강재가 사용될 경우 현장에서 규격자재와 비규격자재를 육안으로 구분하기 어렵게 되었다. 따라서 본 논문에서는 격자지보재의 규격자재와 비규격자재에 대한 성능평가를 실시하여 비규격자재의 항복강도 저하의 문제점을 분석하였다. This paper dealt with contents on the performance evaluation of standardized steel and non-standardized steel of lattice girder. Lattice girder is arch type tunnel supports made of structural steel bar and it is girder used to ensure the stability of tunnel by suppressing any transformation of ground as much as possible during tunnel excavation. The performance evaluation of lattice girder can be conducted through bending strength test, tensile strength test and tunnel standard specification specifies that welding structural steel with over 500MPa yield strength shall be used. However, it is difficult to distinguish visually between standardized steel and non-standardized steel onsite if low-quality structural steel is used. Accordingly, this paper conducted performance evaluation of standardized steel and non-standardized steel of lattice girder to point out the issue of deteriorated yield strength of non-standardized steel, while proposed a method of verifying yield strength onsite.

홍경천(紅景天)추출물(KH101)이 강제유영 흰쥐의 피로회복에 미치는 영향

정혁상,김은영,심은섭,이현삼,문은정,김진화,김선여,손영주,손낙원,Jung, Hyuk-Sang,Kim, Eun-Young,Shim, Eun-Sheb,Lee, Hyun-Sam,Moon, Eun-Jung,Jin, Zhen-Hua,Kim, Sun-Yeou,Sohn, Young-Joo,Sohn, Nak-Won 대한한방내과학회 2008 大韓韓方內科學會誌 Vol.29 No.4

Objectives : Rhodiola rosea has been used in herbal medicine to treat various conditions, such as antimelancholia, antifatigue, improvement of work competence and prevention of altitude sickness. In this study, we investigated effects of Rhodiola rosea extract (KH101) on fatigue in forced swimming rats. Methods : Sprague-Dawley rats were induced with fatigue by forced swimming, then rats in each group were treated with KH101. We observed changes of glucose, LDH and cortisol in serum and LDH, glycogen, hexokinase, citrate synthase MDH, SDH and CK in muscle. Results : Obtained results were as follows: 1. Continuance times of exercise significantly increased in all groups at day 1, in the 50 mg/kg concentration group at day 2, in all groups at day 3 and in the 50 mg/kg conc. group at day 4. 2. In serum, glucose significantly decreased in all concentration groups. 3. In the soleus muscle, LDH significantly decreased in the 50 mg/kg concentration group. HK significantly decreased in the 100 mg/kg conc. group. SDH significantly increased in the 100 mg/kg conc. MDH were significantly decreased in all conc. groups. 4. In the gastrocnemius muscle, HK significantly decreased in all concentration groups, while MDH significantly increased all conc. groups. Conclusions : It is concluded that the KH101 has and anti-fatigue effect in rats. Additional studies are needed to find the mechanism of the association between each single herb.

비파괴법을 활용한 격자지보의 성능평가 기법 제안

정혁상,Jung, Hyuk-Sang 한국터널지하공간학회 2016 한국터널지하공간학회논문집 Vol.18 No.5

본 논문은 비파괴 기법을 활용한 격자지보재의 품질평가 기법에 대한 내용을 다루었다. 일반적인 격자지보재의 성능평가는 강재의 인장강도시험과 육안조사로 이루어진다. 강재의 인장강도시험은 현장에 반입되는 격자지보의 시편을 확보하여 수행하게 되는데 이때 시편 확보를 위해 격자지보재를 훼손시켜야하는 단점을 가지고 있고 대부분의 현장에서는 인장강도시험기를 보유하고 있지 않아 시험인증기관에 의뢰해야하는 불편함을 가지고 있다. 또한 강재 생산시 발행된 성적서(Mile sheet)로 대체하기도 하나 이는 신뢰성이 결여될 수 밖에 없다. 더욱이 현장에서의 육안조사는 신뢰성이 결여되는 문제점을 가지고 있기 때문에 현장에서 자재의 훼손없이, 쉽고 빠르게 격자지보재의 품질을 평가할 수 있는 방법이 필요하게 되었다. 따라서 본 연구에서는 동일 시편에 대한 인장강도시험의 항복강도와 계장화압입시험의 항복강도를 비교 분석하여 비파괴시험법의 적용성을 분석하였다. 시험결과 계장 화압입시험은 95%이상의 정밀도를 보였으며 현장에서 성능평가가 가능한 계장화압입시험에 의한 품질평가기법을 제안하고자 한다. This paper dealt with contents of the quality evaluation method of lattice girder utilizing non-destructive method. Quality evaluation of ordinary lattice girder is performed through the tensile strength test of structural steel and visual inspection. The tensile strength test of structural steel is performed by collecting samples of lattice girder brought into the site, during which lattice girder must be damaged to obtain sample. In addition to such disadvantage, tensile strength tester is not available at the site in most cases, requiring an inconvenient service from test certification agency. In addition, it is substituted by mile sheet issued during the production of structural steel, which inevitably lacks reliability. Furthermore, visual inspection at the site entails a problem of lack of reliability, thereby requiring a method of easily and quickly evaluating the quality of lattice girder without damaging the material. Accordingly, this study comparatively analyzed the yield strength of tensile strength test and the yield strength of instrumented indentation test with same sample. The test results ensured over 95% precision level for the instrumented indentation test, based on which a quality evaluation method based on instrumented indentation test that allowed onsite direct quality evaluation is proposed.

뇌해마의 장기양 조직배양을 이용한 한약물의 뇌신경세포손상 보호효능 연구

정혁상,손낙원,이원철,Jung, Hyuk-Sang,Sohn, Nak-Won,Lee, Won-Chul 대한한방내과학회 2004 大韓韓方內科學會誌 Vol.25 No.3

Objectives : For the screening of neuroprotective effects of medicinal herbs, the complex system of animal models suffer some disadvantages in controlling critical parameters such as blood pressure and body temperature. Additionally, application of drugs to the appropriate brain area sometimes is difficult, due to poor permeability though the blood brain barrier, and so potential protective effects might be masked. Methods : Organotypic hippocampal slice culture (OHSC) method has the advantages of being relatively easy to prepare and of maintaining the general structure, including tissue integrity and the connections between cells. Drugs can easily be applied and neuronal damage can easily be quantified by using tissues and culture media. This study demonstrates neuroprotective effects of Puerariae radix (葛根, PR), Salviae miltiorrhizae radix (丹蔘, SR), Rhei rhizoma (大黃, RR), and Bupleuri radix (柴胡, BR). These were screenedand compared to MK-801, antagonist of NMDA receptors, by using OHSC of 1 week-old Sprague-Dawley rats. Oxygen/glucose deprivation (OGD) were conducted in an anaerobic chamber $(85%\;N_2,\;10%\;CO_2\;and\;5%\;H_2)$ in a deoxygenated glucose-free medium for 60 minutes. Water extracts of each herbs were treated to culture media with $5\;{\mu}g/ml$ for 48 hours. Results : Neuronal cell death in the cultures was monitored by densitometric measurements of the cellular uptake of propidium iodide (PI). PI fluorescence images were obtained at 48 hours after the OGD and medicinal herb treatment. Also TUNEL-positive cells in the CAI and DG regions and LDH concentrations in culture media were measured at 48 hours after the OGD. According to measured data, MK-801, PR, SR and BR demonstrated significant neuroprotective effect against excessive neuronal cell death and apoptosis induced by the OGD insult. Especially, PR revealed similar neuroprotective effect to MK-801 and RR demonstrated weak neuroprotective effect. Conclusions : These results suggest that OHSC can be a suitable method for screening of neuroprotective effects of medicinal herbs. (This work was supported by the research program of Dongguk University and Grant 01-PJ9-PG1-01CO03-0003 from Ministry of Health & Welfare.)

국내 초연약지반의 비배수전단강도 특성 및 개량표준관입시험기 개발

정혁상(Jung Hyuksang),조창구(Cho Changkoo),천병식(Chun Byungsik) 한국지반환경공학회 2009 한국지반환경공학회논문집 Vol.10 No.6

본 연구에서는 국내 초연약지반의 비배수전단강도 특성파악을 위해 남해안 일대 초연약지반 5개 현장에서 표준관입시험, 베인전단시험, 콘관입시험을 실시하여 분석하였고, 초연약지반상에서 적용 가능한 개량표준관입시험기를 개발한 내용을 다루었다. 연구결과 초연약지반(N값 2미만)의 비배수전단강도는 표준관입시험의 결과를 선행연구자들이 제안한 식으로 비배수전단강도를 환산했을 경우 12.5㎪ 이하, 현장시험에서의 베인전단강도 분석결과 50㎪ 이하, 콘관입시험결과 65㎪ 이하의 범위에 있는 것으로 나타났다. 원위치시험의 결과가 표준관입시험의 결과를 비배수전단강도로 환산한 값보다 높게 나타났고 초연약지반의 비배수 전단강도는 실질적으로 상당히 폭넓은 전단강도의 범위를 가지고 있는 것으로 분석되었다. 또한 개량표준관입시험기에 의한 Nm값과 베인전단시험에 의한 비배수전단강도와의 상관관계는 Su=1.76Nm-10.47, 콘관입시험에 의한 비배수전단강도와의 상관관계는 Su=1.82Nm-9.71로 분석되었다. In this study, SPT, FV, and CPT tests were performed at five very soft grounds in southern coast of Korea to characterize the Su of very soft ground. In addition, a new modified SPT that is applicable to very soft ground was developed. Tests results showed that in very soft ground (N<2), the Su was lower than 12.5 ㎪ using the empirical N-Su correlation, and lower than 50 ㎪ and 65 ㎪ using vane shear test and CPT, respectively. It was shown that the results of in-situ tests were higher than those estimated from the N-Su correlation, and it was also demonstrated that the range of estimated Su was quite wide. New correlations that relate the modified SPT Nm with Su from FV and CPT were developed, which are Su=1.76Nm-10.47 and Su=1.82Nm-9.71, respectively.

화강풍화토와 무기질 결합재를 활용한 친환경 흙포장에 관한 연구

정혁상(Jung Hyuksang),장철호(Jang Cheolho),안병제(An Byungjae),천병식(Chun Byungsik) 한국지반환경공학회 2009 한국지반환경공학회논문집 Vol.10 No.4

본 연구의 목적은 기존 흙 포장의 문제점인 장기적인 내구성 결여 및 균열발생을 보완한 친환경적 흙포장재를 개발하기 위한 것이다. 액상형태의 혼합이 용이한 무기질 결합재와 화강풍화토를 첨가량별로 배합하여 일축압축시험 및 투수시험을 실시하였다. 시험결과에 따라 적정 배합비를 산정하고 6가크롬(Cr<SUP>6+</SUP>)검출시험, 재령별 SEM촬영, 동결융해시험을 실시하여 적정성을 검증하였다. 연구 결과, 분말형 무기계 결합재의 배합비는 시멘트:플라이애시:석고의 비율이 각각 50:33:7이 가장 적합한 것으로 판단되었다. 그리고 6가크롬(Cr<SUP>6+</SUP>) 검출시험결과 6가크롬(Cr<SUP>6+</SUP>)의 발생량이 미미하였고, SEM촬영 결과 재령 3일에 에트린자이트 형성이 확인되어 재료가 화학적으로 조기강도 발현이 가능함을 알 수 있었다. In this study, the problem of existing soil pavement is a long-term durability lack and crack occurrence. It complements in order to develop the environmental soil pavement material which composites readily blended mineral binder of liquid and decomposed granite soils. It was estimated optimal mixture proportion for unconfined compressive strength, permeability, CR<SUP>6+</SUP> detection test, SEM test with age, freezing and thawing test. It resulted mixture proportion of powder types mineral binder for rates of cement : fly ash : plaster was optimal rates of 50 : 33 : 7, and CR<SUP>6+</SUP> detection test as a result was a slight production. SEM test with 3days as a result was made Ettringite. It was found that this material was early development of early-strength for chemical. This study indicated that it will execute field appliciability Evaluation test, examination of soil pavement method with decomposed granite soils and mineral binder.

쉴드 TBM 성능예측모델과 굴진자료 분석을 통한 굴진성능 개선방안

정혁상(Jung Hyuksang),강형남(Kang Hyoungnam),최정명(Choi Jungmyung),천병식(Chun Byungsik) 한국지반환경공학회 2010 한국지반환경공학회논문집 Vol.11 No.2

쉴드공법은 막장을 굴착함과 동시에 원통형 강재를 지반속에 추진시켜 터널을 축조하는 공법이다. 1818년 마크 브루넬이 런던의 템즈강 하저 굴착공사에 처음 사용한 이래 지반조건에 따른 다양한 쉴드 TBM이 개발되어 도로, 지하철, 전력구, 상하수도등에 널리 활용되고 있다. 막장상태를 수시로 관찰하며 지반변화에 빠르게 대처할 수 있는 NATM 공법과 달리, 쉴드 공법은 굴진이 시작되면 장비 교체가 거의 불가능하다. 따라서 지반조사 및 실내시험 결과에 따라 적절한 장비를 설계하고, 막장상태에 따라 압입 깊이, 커터헤드 회전속도 등을 효율적으로 관리하여 장비의 성능을 최대한 활용하여 굴착공사를 수행해야 한다. 본 연구에서는 분당선 한강하저터널의 지반조건을 NTNU, QTBM, 합경도, KICT-SNU 등의 모델에 적용하여 굴진성능을 예측하고, 실시공 굴진자료와 비교?분석하여 예측모델의 적용성을 검토하였으며, 한강하저터널 하행선의 굴진성능 저하원인을 분석하였다. Shield method is the tunnel boring method that propels a steel cylinder in the ground and excavates tunnels at once. After Marc Isambard Brunel started using the method for the Thames Riverbed Tunnel excavation in London, many kinds of TBM (Tunnel Boring Machine) developed and applied for the construction of road, railway, electricity channel, pipeline, etc. In comparison with NATM concept that allows to observe ground condition and copes with difficulty. The machine selected before starting construction is not able to be changed during construction in shield TBM. Therefore the machine should be designed based on the ground survey result and experiment, so that the tunnel might be excavated effectively by controlling penetration speed, excavation depth and cutter head speed according to the ground condition change. This research was conducted to estimate penetration depth, excavate speed, wear of disc cutter on Boondang Railway of the Han Riverbed Tunnel ground condition by TBM performance prediction models such as NTNU, QTBM, Total Hardness, KICT-SNU and compare the estimated value with the field data. The estimation method is also used to analyze the reason of poor excavation efficiency at south bound tunnel.

防己가 백서 중대뇌동맥 폐쇄에 의한 국소뇌허혈손상에 미치는 보호효과

정혁상(Hyuk-Sang Jung),이현삼(Hyun-Sam Lee),원란(Ran Won),강철훈(Chul-Hun Kang),손낙원(Nak-Won Sohn) 대한한의학회 2001 대한한의학회지 Vol.22 No.1

저회 뒤채움재의 열저항 특성에 관한 실험적 연구

정혁상(Jung, Hyuk Sang),백용(Baek, Yong),김영석(Kim, Young Seok),공진영(Kong, Jin Young) 대한토목학회 2017 대한토목학회 학술대회 Vol.2017 No.10

하천제방의 건전도 평가를 위한 수치해석적 연구

정혁상(Jung Hyuksang),변요셉(Byun Yoseph),천병식(Chun Byungsik),최봉혁(Choi Bonghyuck),김진만(Kim Jinman) 한국지반환경공학회 2010 한국지반환경공학회논문집 Vol.11 No.11

하천제방 건전도 평가에 대한 영향인자는 누수의 경우 제체, 기초를 구성하는 지반의 투수계수가 있으며, 제방의 높이, 둑마루 폭 등 기하학적 요인이 있고, 비탈면 안정성의 경우 제체 및 기초 지반의 재료적 특성, 제체 비탈면의 형상, 강우나 하천수의 침투에 따른 영향 등이 있다. 본 연구에서는 하천제방 침투해석에 중요한 투수계수 변화에 따른 영향 검토를 위하여 기존 설계결과 타당성 검토, 문헌자료 투수계수 사용에 따른 안정성 평가, 기초지반 투수계수변화에 따른 안정성 검토를 수행하였다. 영향인자 평가 결과, 설계 시 사용되는 투수계수는 동일한 토질에 대해서도 설계문헌에 따라 상이한 것으로 나타났으며, 검토 결과 파이핑 안전율에 큰 영향을 미치는 것으로 평가되었다. An influence factors for soundness evaluation of river levee include consisting embankment in case piping, permeability coefficient of ground, height of embankment, the width of crest, material characteristics of embankment and foundation ground, shape of embankment slope, an influence for penetration of rainfall or river water in case slope stability. In this study, it was operated a feasibility investigation of existing design result, stability evaluation for permeability coefficient use and permeability coefficient change of foundation ground to investigate an influence in line with permeability coefficient change for result of river levee penetration analysis. The evaluation results of influence factors, the permeability coefficient was used in design and it was evaluated influence in safety factor of piping. After the evaluation of influence factors, the permeability coefficient used in the design appears with the fact that differs in a design report about same soil.