• 공업화학
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• 제21권6호
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• pp.593-602
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• 2010

천연고분자물질로서 키토산(chitosan)은 생체적합성, 생분해성, 무독성과 같은 생체재료로서의 우수한 물리화학적 특성에도 불구하고 산(acid)으로 용해하여야 한다는 문제점으로 인해 유전질병이나 암과 같은 불치병의 치료를 위한 생리활성 물질의 생체 내 전달물질로서의 응용이 어려운 실정이다. 따라서 키토산의 이러한 문제점을 획기적으로 해결한 높은 반응성과 강한 양전하(+)를 띠고 있는 저분자량 수용성 키토산(low molecular weight water-soluble chitosan, LMWSC)을 이용하여 난용성 약물뿐만 아니라 치료유전자와 같은 생리활성물질을 안전하게 생체 내 표적위치에 운반할 수 있는 전달체를 제조할 수 있고, 인체 내 무해하고 치료효율이 높은 치료시스템을 개발할 수 있을 것으로 사료된다. 또한 질병의 치료를 위해 무엇보다 중요한 인자는 특정 병소조직에만 발현되는 항원이나 수용체를 밝혀내고 이들과 결합할 수 있는 항체나 리간드를 다양한 생체재료에 개질함으로써 질병 치료의 효율을 높이는 것이 가장 중요한 전략이라고 할 수 있다. 약물이나 유전자를 전달할 수 있는 많은 양이온성 합성고분자에 대한 연구가 활발히 이루어지고 있으나 체내 독성이나 효율성 면에서 많은 문제점을 가지고 있다. 따라서 본 총설에서는 인체 내 전달 효율을 높이기 위한 기능성기의 도입과 유전자와의 복합체 형성을 가능하게 하는 유리 아민기를 가진 인체 무해한 저분자량 수용성 키토산을 이용하여 특정 조직을 표적할 수 있는 다양한 기능성기 도입의 특성과 치료 전략에 대해 기술하고자 한다. 이러한 전달체의 개발은 앞으로 인간에게 유발되는 가장 난치병 중의 하나인 암 치료에 있어 밝은 전망이 될 수 있을 것으로 사료된다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.83-85
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• 2002

Yonsei Cancer Center introduced an IMRT System at the beginning of February, 2002. The system consists of CORVUS(NOMOS) inverse planning machine, LANTIS(SIEMENS), PRIMEVIEW and PRIMART Linac(SIEMENS). The optimization of CORVUS planning system with PRIMART is an important work to get an efficient treatment plan. So, we studied two Finite Size Pencil Beams, 1.0 x 1.0 cm$^2$ and 0.5 x 1.0 cm$^2$, and four leaf transmission sets, 5%, 10%, 20%, 33%. We compared the dose distribution of target volume and delivery efficiency of the plan results.

• Industrial Engineering and Management Systems
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• 제11권1호
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• pp.48-53
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• 2012

Due to the customer needs of reducing cost and delivery date shorting, prompt change in the production plan became more important. In the multi period system (For instance, production line.) where target processing time exists, production, idle and delay risks occur repeatedly for multiple periods. In such situations, delay of one process may influence the delivery date of an entire process. In this paper, we discuss the minimum expected cost of the case mentioned above, where the risk depends on the previous situation and occurs repeatedly for multiple periods. This paper considers the optimal switching frequency to minimize the total expected cost of the production process. In this paper, first, the optimal switching frequency model is proposed. Next, the mathematic formulation of the total expectation is presented. Finally, the policy of optimal switching frequency is investigated by numerical experiments.

• Journal of Periodontal and Implant Science
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• 제53권1호
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• pp.20-37
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• 2023

Purpose: Our pilot study showed that a 3-dimensional dual drug delivery scaffold (DDDS) loaded with Chinese herbs significantly increased the regenerated bone volume fraction. This study aimed to confirm the synergistic anti-inflammatory and osteogenic preclinical effects of this system. Methods: The targets and pathways of parthenolide and naringin were predicted. Three cell models were used to assess the anti-inflammatory effects of parthenolide and the osteogenic effects of naringin. First, the distance between the cementoenamel junction and alveolar bone crest (CEJ-ABC) and the bone mineral density (BMD) of surgical defects were measured in a rat model of periodontitis with periodontal fenestration defects. Additionally, the mRNA expression levels of matrix metallopeptidase 9 (MMP9) and alkaline phosphatase (ALP) were measured. Furthermore, the number of inflammatory cells and osteoclasts, as well as the protein expression levels of tumor necrosis factor-alpha (TNF-α) and levels of ALP were determined. Results: Target prediction suggested prostaglandin peroxidase synthase (PTGS2) as a potential target of parthenolide, while cytochrome P450 family 19 subfamily A1 (CYP19A1) and taste 2 receptor member 31 (TAS2R31) were potential targets of naringin. Parthenolide mainly targeted inflammation-related pathways, while naringin participated in steroid hormone synthesis and taste transduction. In vitro experiments revealed significant antiinflammatory effects of parthenolide on RAW264.7 cells, and significant osteogenic effects of naringin on bone marrow mesenchymal stem cells and MC3T3-E1 cells. DDDS loaded with parthenolide and naringin decreased the CEJ-ABC distance and increased BMD and ALP levels in a time-dependent manner. Inflammation was significantly alleviated after 14 days of DDDS treatment. Additionally, after 56 days, the DDDS group exhibited the highest BMD and ALP levels. Conclusions: DDDS loaded with parthenolide and naringin in a rat model achieved significant synergistic anti-inflammatory and osteogenic effects, providing powerful preclinical evidence.

• Journal of information and communication convergence engineering
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• 제3권1호
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• pp.56-61
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• 2005

In this paper, we present a video rate control scheme for storage and delivery in which the time-varying viewing interests are controlled by human gaze. To track the gaze, the pupil's movement is detected using the three-step process : detecting face region, eye region, and pupil point. To control bit rates, the quantization parameter (QP) is changed by considering the static parameters, the video object priority derived from the pupil tracking, the target PSNR, and the weighted distortion value of the coder. As results, we achieved human interfaced visual model and corresponding region-of-interest rate control system.

• 대한환경공학회지
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• 제39권12호
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• pp.714-722
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• 2017

수질오염총량관리제도(이하 총량제)는 하천의 목표수질을 달성하기 위해 유역에서 배출되는 오염물질의 총량을 관리하는 제도이다. 유역에서 배출되는 오염물질의 허용총량은 수질모델을 활용하여 산정하며, 이과정에서 오염부하량은 발생, 배출, 유달부하량으로 구분할 수 있다. 유달부하량은 배출부하량과 유달율의 곱으로 계산되며 유달율은 유역에서 배출된 오염물질이 하천의 특정지점에 도달하는 비율로 정의된다. 본 연구에서는 Hwang(2016) 등이 제시한 기준유량 조건의 유달율 추정방법을 영강유역에 적용하고 QUALKO2 수질모델의 수질 입력자료를 생성하여 기준유량 조건의 유달율 산정방법(식 (3))과 평균 개념의 유달율 산정 방법(식 (2))의 비교분석을 통해 유달율 추정방법에 대한 검증 연구를 수행하였다. 연구결과, 유달율 함수식은 식 (2)와 식 (3) 모두 사용 가능하나, 배출계수 적용에 따라 방법론을 달리할 필요가 있다. 식 (2)를 사용할 경우는 배출계수를 저수량, 평수량 구분없이 1로 동일하게 사용해야 하며, 식 (3)을 사용할 경우는 기술지침에서 정한 배출계수(저수량 0.15, 평수량 0.5)를 적용해야 할 것으로 판단된다.

• 한국산학기술학회논문지
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• 제17권4호
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• pp.340-350
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• 2016

의료법에서는 의원은 외래환자를, 상급종합병원은 중증의 입원환자를 전문적으로 치료하는 의료기관으로 규정하고 있다. 그러나 일차의료를 제공하는 의원의 외래환자수는 위축되는 반면 상급종합병원의 외래진료비 비중은 지속적으로 증가하고 있다. 이 연구에서는 우리나라 의료전달체계를 정상화하기 위한 보다 근원적인 방안으로 두 가지 정책안을 제시하고 이 정책을 정착시키고 성공시키기 위한 보건의료정책 거버넌스에 관한 제안을 담고 있다. 상급종합병원의 중증 환자 진료기능을 강화하기 위하여 현행 종별가산율을 외래와 입원 종별가산율로 분리하고 외래진료비 목표관리제 도입이라는 두 가지 방안을 제시하였다. 그리고 이들 정책안을 큰 부작용없이 성공시키기 위한 보건의료 정책 거버넌스를 제안하였다. 보건의료 정책 거버넌스는 의료공급자, 환자의 참여와 동기부여가 전제되어야 하며 장기적인 관점에서는 향후 의료 질을 반영할 수 있도록 설계되어야 한다.

• 센서학회지
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• 제32권6호
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• pp.418-424
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• 2023

Natural killer (NK) cells play a crucial role in combating infections and tumors. However, their therapeutic application in solid tumors is hindered by challenges, such as limited lifespan, tumor penetration, and delivery precision. Our research introduces a novel ultrasonic actuation technique to navigate NK cells more effectively in the vascular system, particularly at vessel bifurcations where targeted delivery is most problematic. We use a hemispherical ultrasonic transducer array that generates phase-modulated traveling waves, focusing on an ultrasound beam to steer NK cells using blood-flow dynamics and a focused acoustic field. This method enables the precise obstruction of non-target vessels and efficiently directs NK cells toward the tumor site. The simulation results offer insights into the behavior of NK cells under various conditions of cell size, radiation pressure, and fluid velocity, which inform the optimization of their trajectories and increase targeting efficiency. The experimental results demonstrate the feasibility of this ultrasonic approach for enhancing NK cell targeting, suggesting a potential leap forward in solid tumor immunotherapy. This study represents a significant step in NK cell therapeutic strategies, offering a viable solution to the existing limitations and promising enhancement of the efficacy of cancer treatments.

• Radiation Oncology Journal
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• 제32권3호
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• pp.103-115
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• 2014

To summarize current knowledge regarding mechanisms of radiation-induced normal tissue injury and medical countermeasures available to reduce its severity. Advances in radiation delivery using megavoltage and intensity-modulated radiation therapy have permitted delivery of higher doses of radiation to well-defined tumor target tissues. Injury to critical normal tissues and organs, however, poses substantial risks in the curative treatment of cancers, especially when radiation is administered in combination with chemotherapy. The principal pathogenesis is initiated by depletion of tissue stem cells and progenitor cells and damage to vascular endothelial microvessels. Emerging concepts of radiation-induced normal tissue toxicity suggest that the recovery and repopulation of stromal stem cells remain chronically impaired by long-lived free radicals, reactive oxygen species, and pro-inflammatory cytokines/chemokines resulting in progressive damage after radiation exposure. Better understanding the mechanisms mediating interactions among excessive generation of reactive oxygen species, production of pro-inflammatory cytokines and activated macrophages, and role of bone marrow-derived progenitor and stem cells may provide novel insight on the pathogenesis of radiation-induced injury of tissues. Further understanding the molecular signaling pathways of cytokines and chemokines would reveal novel targets for protecting or mitigating radiation injury of tissues and organs.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.53-60
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• 2002

Motion of lung tumors from respiration has been reported in the literature to be as large as of 1-2 cm. This motion requires an additional margin between the Clinical Target Volume (CTV) and the Planning Target Volume (PTV). While such a margin is necessary, it may not be sufficient to ensure proper delivery of Intensity Modulated Radiotherapy (IMRT) to the CTV during the simultaneous movement of the DMLC. Gated treatment has been proposed to improve normal tissues sparing as well as to ensure accurate dose coverage of the tumor volume. The following questions have not been addressed in the literature: a) what is the dose error to a target volume without gated IMRT treatment\ulcorner b) what is an acceptable gating window for such treatment. In this study, we address these questions by proposing a novel technique for calculating the 3D dose error that would result if a lung IMRT plan were delivered without gating. The method is also generalized for gated treatment with an arbitrary triggering window. IMRT plans for three patients with lung tumor were studied. The treatment plans were generated with HELIOS for delivery with 6 MV on a CL2100 Varian linear accelerator with a 26 pair MLC. A CTV to PTV margin of 1 cm was used. An IMRT planning system searches for an optimized fluence map ${\Phi}$ (x,y) for each port, which is then converted into a dynamic MLC file (DMLC). The DMLC file contains information about MLC subfield shapes and the fractional Monitor Units (MUs) to be delivered for each subfield. With a lung tumor, a CTV that executes a quasi periodic motion z(t) does not receive ${\Phi}$ (x,y), but rather an Effective Incident Fluence EIF(x,y). We numerically evaluate the EIF(x,y) from a given DMLC file by a coordinate transformation to the Target's Eye View (TEV). In the TEV coordinate system, the CTV itself is stationary, and the MLC is seen to execute a motion -z(t) that is superimposed on the DMLC motion. The resulting EIF(x,y)is inputted back into the dose calculation engine to estimate the 3D dose to a moving CTV. In this study, we model respiratory motion as a sinusoidal function with an amplitude of 10 mm in the superior-inferior direction, a period of 5 seconds, and an initial phase of zero.