• 한국안전학회지
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• 제33권2호
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• pp.86-93
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• 2018

Recently, the use of composite steel plate concrete structural modules filled with concrete between steel plates of complex internal structure, in which a large amount of studs are installed, is increasing in order to reduce the weight and to increase workability of structures such as LNG storage tanks. However, in Korea, there is no systematic criterion for evaluating the construction performance of composite steel plate concrete structural modules. Therefore, in this study, we propose a filling guideline of concrete for composite steel plate structural module. For this purpose, high filling performance concrete with general strength range was formulated and tested for filling ability and permeability for each formulation. Rheology analysis was performed to quantitatively evaluate the flow characteristics of concrete. The reliability of $T_{500}$ and plastic viscosity was evaluated to reflect the results of each test, and a guideline for high filling concrete satisfying the reliability of 0.9 or more was derived by reflecting the results of the study on the relationship between the $T_{500}$ and plastic viscosity. Through final fill-box test, filling performance was verified and guidelines were suggested.

• 한국가스학회지
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• 제19권3호
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• pp.38-43
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• 2015

지하에 매설된 도시가스 배관은 부식으로부터 보호하기 위하여 전기방식조치를 하도록 하고 있으며, 전기방식시설의 효과적인 유지관리를 위해 1년마다 배관의 전위를 측정 하도록 하고 있다. 방식전위의 측정은 테스트박스(T/B)에서 실시하게 되는데, 도심에 설치된 T/B의 경우 대부분 도로상에 설치되어 있어 전위를 측정할 때 어려움이 있다. 즉, 교통량이 많은 도로에서 전위를 측정하기 위해서는 차량을 통제하거나, 교통량이 적은 심야에 실시해야 하는 등 어려움이 있다. 본 연구에서는 이러한 방식전위 측정의 문제점을 해결하기 위해 고체기준전극 및 무선통신기술을 이용한 원격전위 측정시스템 개발에 관한 연구를 수행하였다. 고체기준 전극을 개발하여 실험실에서 성능테스트를 실시하고, 도시가스 배관이 설치된 현장에 직접 매설하여 전위 값의 변화를 관찰하였다. 또한, 무선통신을 이용하여 측정된 전위값을 서버로 전송하고, 사무실에서 전위값의 변화를 확인하였다. 고체기준전극을 이용한 전위값은 국내에서 사용되고 있는 타사 제품과 큰 차이가 없는 것으로 확인되었으며, 현장에서 측정한 전위 값과 웹서버로 보내진 전위값의 차이는 없었다. 개발된 고체기준전극은 향후 도심에 설치된 테스트 박스의 전위를 차량을 이용하여 측정하는데 사용할 계획이다.

• 한국산업보건학회지
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• 제19권1호
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• pp.25-29
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• 2009

The purpose of this study was to investigate the effect of two different lifting posture on the plantar foot pressure, force and COP(center of pressure) trajectory path during object lifting. Fourteen healthy adults who had no musculoskeletal disorders were instructed to lift with two postures(stoop and squat) and two object weights(empty box and 10 kg box). Plantar foot pressures, forces and COP trajectory path were recorded by the F-mat system(Tekscan, Boston, USA) during object lifting with barefoot. Plantar foot surface was defined as seven regions for pressure measurement; two toe regions, three forefoot regions, one midfoot region and one heel region. Paired t-test was used to compare the outcomes of peak pressure and maximum force with different two lifting postures and two object weights. Plantar peak pressure and maximum force under hallux was significantly greater in squat posture than stoop posture during the two different boxes lifting(p<.05). During the empty box lifting, maximum force under lessor toes was significantly less and plantar peak pressure under second metatarsal region was significantly greater in squat than stoop(p<.05). Maximum force under heel was significantly less in squat than stoop posture during 10kg box lifting(p<.05). Finally, COP trajectory path was significantly greater in squat than stoop(p<.05). These findings confirm that there are significantly change in the structure and function of the foot during the object lifting with different posture. Future studies should focus on the contribution of both structural and functional change to the development of common foot problems in adults.

• 한국환경과학회지
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• 제31권8호
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• pp.691-706
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• 2022

Magnetic activated carbon was prepared by adding a magnetic material to activated carbon that had been prepared from waste citrus peel in Jeju. The adsorption characteristics of an aqueous solution of the antibiotic trimethoprim (TMP) were investigated using the magnetic activated carbon, as an adsorbent, and response surface methodology (RSM). Batch experiments were carried out according to a four-factor Box-Behnken experimental design affecting TMP adsorption with their input parameters (TMP concentration: 50~150 mg/L; pH: 4~10; temperature: 293~323 K; adsorbent dose: 0.05~0.15 g). The significance of the independent variables and their interaction was assessed by ANOVA and t-test statistical techniques. Statistical results showed that TMP concentration was the most effective parameter, compared with others. The adsorption process can be well described by the pseudo-second-order kinetic model. The experimental isotherm data followed the Langmuir isotherm model. The maximum adsorption capacities of TMP, estimated with the Langmuir isotherm model were 115.9-130.5 mg/g at 293-323 K. Also, both the thermodynamic parameters, ΔH and ΔG, have both positive values, indicating that the adsorption of TMP by the magnetic activated carbon is an endothermic reaction and proceeds via an involuntary process.

• 대한방사선치료학회지
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• 제16권2호
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• pp.81-89
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• 2004

목적 : 방사선 치료에서 환자와 근무자에 의한 setup error등은 치료성적이 결정될 수 있는 중요한 요인이라고 볼 수 있다. 이에 환자와 근무자에 의한 SET-UP ERROR가 환자치료에 미치는 영향에 대하여 비교 분석하고자 한다. 대상 및 방법 : 실험은 human phantom을 이용하여 C-T scan시 Left방향의 Lateral Level을 0mm, 3mm, 5mm, 7mm, 10mm, 15mm, 20mm로 변화시켜 SET-UP ERROR를 유발하였고, 각각에 대하여 C-T scan을 시행하였고, SET-UP ERROR가 유발된 각각의 C-T image를 얻어 RTP장비를 이용하여 임상에서 많이 사용되는 plan을 사용하여 7개의 C-T image에 각각의 plan-대향이문조사plan, Box-4문조사plan, 3Dimension plan-3개를 시행하여 총 21개의 plan을 실시하였다. (CTV+1cm margin, CTV+0.5cm margin, CTV+0.3cm margin = PTV) 이렇게 얻어진 plan을 이용하여 SET-UP ERROR가 유발이 안된 0mm image의 plan 3개와 SET-UP ERROR가 있는 6개 image의 총 18개의 plan을 대향이문조사plan, Box4문조사plan, 3Dimension plan으로 나누어 선량분포와 DVH를 이용하여 비교 분석하였다. 결과 : SET-UP ERROR를 유발시킨 3mm, 5mm, 7mm C-T image에서는 대향이문조사plan을 제외하고는 모든 plan에서 충분히 치료에 영향을 미칠만한 변화가 나타났으며, Box4문조사plan에서는 SET-UP ERROR에 의한 CTV가 Field 밖으로 빠짐으로 선량분포와 DVH가 나빠지는 현상이 나타났다. 결론 : 환자의 움직임, CTV 3차원형태, CTV margin등이 치료에 영향을 미친다. 이러한 영향을 줄이기 위해서는 환자의 긴장감과 움직임을 줄일 수 있는 환자교육과 정확한 환자setup능력이 치료의 승패를 좌우한다고 생각된다. 또한 재현성과 움직임을 줄일 수 있는 accessory 개발과 보급이 중요하다.

• 방송과미디어
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• 제19권2호
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• pp.36-45
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• 2014

With major sports events such as FIFA World Cup and The Olympic Games coming up, UHDTV technology has been given a major push by broadcasters, test and measurement (T&M), and consumer electronics (TV and set-top box) manufacturers. The increase in picture resolution ($3840{\times}2160$) for 4K and ($7680{\times}4320$) for 8K compared to current HDTV ($1920{\times}1080$), as well as the need to deliver these services in higher frame rates (50/60 up to 100/120fps) translate to a big challenge in UHDTV content delivery to households over terrestrial transmission due to higher data rates. DVB-T2 has been favored by many countries across the world as it is proven to give the best spectral efficiency for terrestrial broadcasting. On the other hand MPEG-4 appears to be the bottleneck for UHDTV since a much higher data rate is needed to deliver such services. Therefore HEVC becomes mandatory for UHDTV delivery over DVB-T2. In this paper, we will give an overview about a complete end-to-end solution for UHDTV delivery over DVB-T2 based on a realistic SFN scenario in Seoul metropolitan area.

• 한국지반공학회논문집
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• 제17권6호
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• pp.163-171
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• 2001

콘크리트 구조물과 토공의 인접부인 구조물 뒷채움의 구조적 연속성을 위해서는 뒷채움 시공이 중요하다. 뒷채움부의 구조적 연속성을 증가시키기 위해서는 양질의 뒷채움재 사용과 대형 진동다짐장비에 의한 정밀다짐이 효과적이다. 그러나 정밀다짐시에 발생하는 과도한 토압에 의해 암거 구조물에 구조적 결함이 발생할 수 있다. 본 연구에서는 다짐재와 다짐방법을 변화시키면서 2개소의 암거를 건설하였다. 뒷채움재로는 선택층재와 노상토재를 사용하였다. 뒷채움 다짐시에 큰 다짐에너지를 얻기 위하여 대부분의 경우 총중량 11~12톤의 다짐롤러를 2000rpm 에서 2400rpm의 주파수로 적용하였다. 노상토를 사용하여 뒷채움 시공을 하는 경우에는 충격완화재를 설치하여 동적 수평하중에 미치는 영향을 분석하였다. 충격완화재로는 EPS재와 타이어 칩을 사용한 패널들을 사용하였으며, 뒷채움 시공시에 이들 충격완화재를 암거의 외벽체에 부탁하였다. 본 논문에서는 콘크리트 암거의 뒷채움 시공시에 발생하는 동적지응력 특성을 기술하였다. 계측 결과, 다짐하중에 의한 수직토압과 수평토압의 크기는 다짐재료, 다짐 측정깊이 및 다짐방법에 의존하고 있었다. 뒷채움 다짐시에는 정적토압계수 보다 큰 동적토압계수$(\DeltaK_{dyn}=\DeltaK\sigma_h\DeltaK\sigma_v)$를 나타내고 있어 동적토압에 의해 암거에 유해한 영향을 줄 수 있다. 충격완화재 EPS(t=10cm)와 고무계(t=5cm)는 암거 벽체에 작용하는 동적 수평토압을 경감시키는데 효과적인 것을 알았다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.551-558
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• 2001

The horizontal drain method is one of methods improving reclamation ground. This method reduces consolidation time by using drained installed horizontally, and negative pressure is applied on end of these drains by vacuum pump. But, effective negative pressure still wasn't evaluated in applying this method to reclamation ground. To estimate optimum negative pressure, soil box test that make a model the in-situ by installing horizontal drains in the center is performed pressing different vacuum pressure In the laboratory, and the variations in settlement and volume of drained water through the drains during consolidation process were measured. Also, water content with distance from drain and with depth is measured after the test.

• Steel and Composite Structures
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• 제14권2호
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• pp.105-120
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• 2013

Flexural behavior of thin walled steel-concrete composite sections as cross sections for beams is investigated by conducting an experimental study supported by applicable analytical predictions. The experimental study consists of testing up to failure, simply supported beams of effective span 1440 mm under two point loading. The test specimens consisted of composite box and channel (with lip placed on tension side and compression side) sections, the behavior of which was compared with companion empty sections. To understand the role of shear connectors in developing the composite action, some of the composite sections were provided with novel simple bar type and conventional bolt type shear connectors in the shear zone of beams. Two RCC beams having equivalent ultimate moment carrying capacities as that of composite channel and box sections were also considered in the study. The study showed that the strength to weight ratio of composite beams is much higher than RCC beams and ductility index is also more than RCC and empty beams. The analytical predictions were found to compare fairly well with the experimental results, thereby validating the applicability of rigid plastic theory to cold-formed steel concrete composite beams.

• IMMUNE NETWORK
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• 제8권2호
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• pp.39-45
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• 2008

Background: Down regulation of major histocompatibility complex class II transactivator (CIITA) has been identified as a major factor of immunosuppression in sepsis and the level of CIITA expression inversely correlates with the degree of severity. However, it has not been fully elucidated whether the lower expression of CIITA is a cause of disease process or a just associated sign. Here we determined whether the CIITA deficiency decreased survival rate using murine sepsis model. Methods: Major histocompatibility complex class II (MHC-II) deficient, CIITA deficient and wild type B6 mice were subjected to cecal ligation puncture (CLP) surgery. CIITA and recombination activation gene (RAG)-1 double deficient mice were generated to test the role of lymphocytes in CIITA-associated sepsis progression. Results: Sepsis mortality was enhanced in CIITA deficient mice, not by impaired bacterial clearance resulted from CD4 T cell depletion, but hyper-inflammatory response such as excessive release of a pro-inflammatory cytokine, high-mobility group box 1 (HMGB1). Conclusion: Our results demonstrate that CIITA deficiency affects the course of sepsis via the unexpected function of CIITA, regulation of cytokine release.