• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.401-409
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• 2005

In this study, reinforced dual concrete beam (RDC beam) composed of steel fiber reinforced concrete (SFRC) in the tension part and normal strength concrete (NSC) in the compression and remaining part is proposed. It is the epochal structural system that improves the overall structural performances of beam by partially superseding the steel fiber reinforced concrete in the lower tension part of conventional reinforced concrete beam (RC beam). Flexural and shear tests are performed to prove the structural excellence of RDC beam in comparison with RC beam. An analytical method is proposed to understand the flexrual behavior and is compared to experimental results. And for shear behavior, experimental results are compared to empirical equations predicting the ultimate shear strength of full-depth fiber reinforced concrete beam to examine the behavior of RDC beam under shear. From this studies, it is proved that RDC beam has more superior structural performance than RC beam, and the analytical method for flexural behavior agrees well with experimental results, and the partial-depth fiber reinforcements have no noticeable effect on ultimate shear strength but it is considerably effective to control and prevent evolutions of crack.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.1
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• pp.71-82
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• 1996

In this paper, the Doppler phase error due to the relative velocity between a satellite and the earth station in communications using a low earth orbit mobile satellite is detected. The performance of BPSK system in the presence of Rician fading with Doppler phase error and interference, noise is compared with that of the system disturbed by Doppler phase error and noise only. The expression of error rate performance of BPSK system is derived as the type of complementary error function. The numerical calculation of the induced equation are performed in terms of satellite-height, orbit-eccentricity, the velocity of the earth, Rician fading parameter, signal to interference rateio (SIR), the ratio of carrier frequency and base band bit rate. The main conclusion that can be drawn from this analysis is that Rician fading channel environment with Doppler phase error and interference effect yields severe performance degradation than Do- ppler phase error and noise effect in satellite communication channel. And using the numerical calculation, we give a quantitative insight how much the satellite communication channel parameters degrade the system performance. Furthermore it is shown that an appropriate transmission power control for the performance enhancement is beneficial to the new satellite communication system planning.

• Journal of the Korean Society of Radiology
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• v.6 no.5
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• pp.395-402
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• 2012

4D-Radiation Therapy is the optimal treatment to track moving organs(tumor) and give the appropriate prescription dose to tumor and low radiation dose to normal tissue surrounding tumor volume. The ABCHES is a 4DRT devices maintaining shallow breathing to patients. It allows the tumor's movement was minimize. Meanwhile, Abdominal compression device is limited the breath compressing abdomen on patients. In this paper we will quantitative analysis the movement of tumor on only ABCHES versus ABCHES with Abdomal compression device and Analysis tumor dose and normal tissue's dose by Dose Volume Histogram on two parts. The result of Comparision ABCHES and ABCHES with Abdominal compression device, SI(Superior-Inferior) direction, AP(Anterior-Posterior) direction and LR(Left-Right) direction was limited 1.0 mm, 0.2 mm, 0.2 mm(average). and also reduction rate of voluume in HPTV was $16{\pm}2%$, and LPTV was $15.8{\pm}0.8%$ under only using ABCHES and ABCHES with compression. The analysis dose volume histogram was more radiation dose in ABCHES and abdominal compression device than only using ABCHES, and less normal tissue-ipsilateral lung, whole lung, kidney-dose in ABCHES and abdominal compression device than only using ABCHES. The overall analysis was ABCHES with abdominal compression better than only using ABCHES method. In hereafter it will be studies that limitation of ABCHES and abdomonal compression device. In other words, patient's discomfort on compression intensity, method of application on patient with inaccurate respiration cycle.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.185-194
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• 2012

Deepwater oil is becoming more attractive because most onshore and shallow water oil is developing or developed. With the on-going trend to deepwater oil developments, flow assurance problems which prevent oil flow from reservoir to processing facilities are becoming an issue because deposited material can be occurred in case oil is exposed to very different environment from reservoir. Wax deposition which is one of flow assurance problems can be a major technical and economic issue because it is very sensitive to temperature. In order to predict and mitigate wax problems, the precise measurement of wax appearance temperature (WAT) which is the starting temperature of wax precipitation is very important. Various methods have been suggested for WAT measurement of opaque oil because there is no standard method for opaque oil. In this study, the WAT of opaque oil samples was measured using viscosity measurement method, differential scanning calorimetry, filter plugging method, and pressurized filter plugging method. Wax deposition test and high temperature gas chromatography analysis were applied to verify measured WAT. As a result of study, the WAT of opaque oils was successfully measured and verified. If WAT measurement methods of opaque oil related to oil characteristics is systematized using the results of this study, it can be a valuable tool for WAT measurement of opaque oil and flow assurance related to wax deposition.

• Korean Journal of Ecology and Environment
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• v.38 no.3 s.113
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• pp.393-402
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• 2005

The field scale experiment was performed to examine the effect of plant coverage on the constructed wetland performance and recommend the optimum development and management of macrophyte communities. Four sets (each set of 0.88 ha) of wetland (0.8 ha) and pond (0.08 ha) systems were used. Water flowing into the Seokmoon estuarine reservoir from the Dangjin stream was pumped into wetland system. Water depth was maintained at 0.3 ${\sim}$ 0.5 m and hydraulic retention time was managed to about 2 ${\sim}$ 5 days; emergent plants were allowed to grow in the wetlands. After three growing seasons of the construction of wetlands, plant coverage was about 90%, even with no plantation, from bare soil surfaces at the initial stage. During the start up period of constructed wetlands, lower water levels should be maintained to avoid flooding newly plants, if wetland plants are to be started from germinating seeds. Effluent T-N concentration in low plant coverage wetland was higher in winter than high plant coverage wetland, whereas no T-P effluent concentration and removal efficiency difference was observed within 15% plant coverage. Dead vegetation affected nitrogen removal during winter because it is a source of organic carbon which is an essential parameter in denitrification. Biomass harvesting is not a realistic management option for most constructed wetland systems because it could only slightly increase the removal rate and provide a minor nitrogen removal pathway due to lack of organic carbon.

• Journal of Life Science
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• v.22 no.5
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• pp.595-599
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• 2012

Allergic response is associated with mast cells, through the release of arachidonic acid, proinflammatory cytokines, and histamine. We investigated the effect of Platycodon grandiflorum including platycodin D (PG-Platycodin D) on allergic responses in an animal model and on mast cell degranulation. PG-Platycodin D suppressed the release of ${\beta}$-hexosaminidase, a type of marker associated with degranulation. PG-Platycodin D efficiently inhibited the passive cutaneous anaphylaxis (PCA) reaction in ICR mice. In addition, molecular analysis demonstrated that PG-Platycodin D inhibited mRNA expression of both IL-3. These results suggest that PG-Platycodin D can inhibit mast cell degranulation through the inhibition of IL-3 mRNA expression, and that PG-Platycodin D may potentially serve as an anti-allergic agent.

• Journal of the Korean Chemical Society
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• v.57 no.4
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• pp.493-498
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• 2013

Liposomes, which can deliver payload at target site, have been studied as drug carrier. However, conventional liposomes have limitation for drug release at target site. Therefore, we developed hydroxyapatite (HA) coated ultrasound sensitive liposomes to increase drug release at target site and to enhance stability in blood stream. Control liposome was prepared using hydrogenated soy phosphatidylcholine (HSPC) and cholesterol, and then we assessed HA coating on the surface of control liposomes using calcium acetate, phosphoric acid, and 25% ammonium solution. Doxorubicin was used as a model drug. Size of HA coated liposomes was 120 nm and encapsulation efficiency of doxorubicin in liposomes was up to 95%. Size of HA coated liposomes are not changed in 30% serum solution, however, the control liposomes was 1.4 fold increased. After ultrasound triggered drug release from liposomes, intracellular efficiency of drug released from HA coated liposomes was 3 fold increased compared to control liposomes. In this study, we developed ultrasound sensitive liposomes to enhance drug release, which will be applied in controlled drug release at disease site.

• Clean Technology
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• v.20 no.3
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• pp.226-231
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• 2014

This study presents a micromolding for the synthesis of Janus particles with reconfigurable shape by pH stimuli. First, we use acrylic acid (AA) as pH responsive monomer in the hydrophilic part and trimethylolpropane triacylate (TMPTA) in the hydrophobic part, respectively. The change of acidity in solvent induces the swelling of hydrophilic part in the Janus particles. The pH-responsive Janus particles show different swelling ratio of hydrophilic part in according to composition of acrylic acid in diverse range (0-70% v/v) and pH (3-11). As the concentration of acrylic acid in the hydrophilic part and environmental pH increase, the hydrophilic part in the Janus particles is proportionally swelled. Second, we fabricate novel type of Janus particles with two different hydrophilicities. As a proof of concept, we have applied acrylic acid (AA) and 2-(dimethylamino)ethyl methacrylate (DAEMA) into each part because the monomers provide reverse responsive activity. As expected, these Janus particles show different shape anisotropies with reconfigurable property in accordance with the polarity of each part at same acidity of environmental solvent. We envision that the stimuli responsive Janus particles have a wide application from fundamental science to diagnostic apparatus.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.84-84
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• 1999

최근 큰 잔류분극을 가진 강유전체 Pb(Zr, Ti)O3 박막을 이용한 비휘발성 기억소자의 연구가 활발히 진행되고 있다. 그러나 Pb(Zr, Ti)O3 박막을 비휘발성 기억소자로 응용하는 경우 분극피로(polarization fatigue), imprint, 누설전류 등의 문제점이 나타나는 것으로 알려져 있다. 특히 분극반전 횟수가 증가할수록 잔류분극이 감소하는 분극피로 현상은 비휘발성 기억소자의 응용에 있어서 치명적인 장애가 되므로 기억소자의 실용화를 위해서는 분극피로 현상의 개선이 무엇보다 중요하다. 본 연구에서는 Pb(Zr, Ti)O3 강유전체 박막의 분극피로 현상을 규명하고 개선하기 위해서 다음과 같은 세가 실험적 방법으로 접근하였다. 먼저 Pt와 금속산화물인 LaNiO3을 이용하여 상·하부 전극을 달리하여 제조한 축전기에 대해서 분극피로 특성을 관찰하고 이로부터 분극피로 현상에 대한 전극의 효과를 조사하였다. 여기서 금속산화물인 LaNiO3 박막과 Pt 박막은 r.f. 스퍼트 법으로 증가하였으며 Pb(Zr, Ti)O3 박막은 LaNiO3/Si(100)/와 Pt/Ti/SiO2/i(100) 기판위에 졸겔법으로 제조하였다. 다음으로 분극피로된 박막의 상부전극에 극성이 다른 직류전압을 인가해주었을 때 나타나는 분극회복 현상을 광범위하게 관찰하였으며, 특히 직류전압의 극성에 따라 비대칭적인 분극회복 특성을 보였다. 마지막으로 이와 같은 직류전압에 대한 비대칭적인 분극회복현상에 착안하여 양과 음의 방향으로 바이어스된 스윗칭 펄스를 인가하여 분극피로 특성을 조사한 결과 비대칭적인 분극피로 현상을 관찰할 수 있었다. 이와 같은 Pv(Zr, Ti)O3 박막의 분극피로와 회복의 비대칭적인 현상은 분극피로 현상의 기구를 밝히는 중요한 근거가 되었으며, 본 연구에서는 하부 계면에서의 산소빈자리의 역할로 분극피로 현상을 모형화하였다.식각하기 시작하였으며, 19.5J/cm2에서 유리기판의 rudraus(격벽 두께 130$\mu\textrm{m}$)까지 식각하였다. 대한 정보(RDF)는 명확하게 얻을 수 있었다.nospec과 SEM으로 관찰하였다. 또한 Ge 함량 변화에 따른 morphology 관찰과 변화 관찰을 위하여 AFM, SEM, XRD를 이용하였으며, 이온주입후 열처리 온도에 따른 활성화 정도의 관찰을 위하여 4-point probe와 Hall measurement를 이용하였다. 증착된 다결정 SiGe의 두게를 nanospec과 SEM으로 분석한 결과 Gem이 함량이 적을 때는 높은 온도에서의 증착이 더 빠른 증착속도를 나타내었지만, Ge의 함량이 30% 되었을 때는 온도에 관계없이 일정한 것으로 나타났다. XRD 분석을 한 결과 Peak의 위치가 순수한 Si과 순수한 Ge 사이에 존재하는 것으로 나타났으며, ge 함량이 많아짐에 따라 순수한 Ge쪽으로 옮겨가는 경향을 보였다. SEM, ASFM으로 증착한 다결정 SiGe의 morphology 관찰결과 Ge 함량이 높은 박막의 입계가 다결정 Si의 입계에 비해 훨씬 큰 것으로 나타났으며 근 값도 증가하는 것으로 나타났다. 포유동물 세포에 유전자 발현벡터로써 사용할 수 있음으로 post-genomics시대에 다양한 종류의 단백질 기능연구에 맡은 도움이 되리라 기대한다.다양한 기능을 가진 신소재 제조에 있다. 또한 경제적인 측면에서도 고부가 가치의 제품 개발에 따른 새로운 수요 창출과 수익률 향상, 기존의 기능성 안료를 나노(nano)화하여 나노 입자를 제조, 기존의 기능성 안료에 대한 비용 절감 효과등을 유도 할 수 있다. 역시 기술적인 측면에서도 특수소재 개발에 있어 최적의 나노 입자 제어기술 개발 및 나노입자를 기능성 소재로 사용하여 새로운 제품의 제조와 고압 기상 분사기술의 최적화에

• Journal of Bio-Environment Control
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• v.18 no.1
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• pp.23-28
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• 2009

This study was conducted to evaluate the effect of optimized environment conditions with growth stage in photoautotrophic micropropagation on the growth of potato (Solanum tuberosum L. cv. Dejima) plantlets and energy efficiency. Optimum environment conditions at each stage were decided in our previous study. For the evaluation of optimized environment control, potato plantlets were cultured under four different conditions: photoautotrophic optimum conditions of photosynthetic photon flux density (PPFD) and $CO_2$ levels with growth stage (POG), photoautotrophic constant condition with average PPFD and $CO_2$ levels (PCA), photoauototrophic constant condition with maximum PPFD and $CO_2$ levels (PCM), and photomixotrophic conventional condition with 3% sucrose (PMC) as control. As a result, environment control with growth stage (POG) significantly promoted all the growth characteristics such as the number of nodes and unfolded leaves, shoot height, shoot diameter, and fresh and dry weights of potato grown in vitro. In addition, based on dry weight consumed electricity and $CO_2$ were the lowest in POG suggesting the highest energy efficiency among the treatments. After transferring potato plantlets to greenhouse, the plantlets under POG showed vigorous growth, which was pretty similar with those under PMC. The accumulations of dry matter in POG were 4.7 times in vitro and 3.8 times in greenhouse as much as those in the conventional control (PCM). Thus, we concluded that in vitro environment control with growth stage induced vigorous growth of potato plantlets both in vitro and in greenhouse with less energy consumption.