• 대한화장품학회지
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• 제27권1호
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• pp.119-131
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• 2001

Exposure of the human skin to UV-light can cause sun-tanning, photoaging and even photo-carcinogenesis. Melanin is important in protecting the skin against UV damage, but excessive or uneven melanin production can lead to the formation of freckles and aged spot. Control of hyperpigmentation is becoming even more important as aged population continues to grow. These needs led us to develop effective and safe depigmenting-agent, kojyl 3-aminopropyl phosphate (kojyl-APPA), called Whitegen. The development of whitegen was based on the fact that phosphate group of 3-aminopropyl phosphate can make kojic acid more compatible to the skin membrane and more stable. Instability of kojic acid has been a problem in cosmetic use. The insertion of phosphoester group has been recognized as a powerful tool to improve such physical properties as solubility and stability, because the phosphodiester residue is well characterized as a non-toxic moiety, having a high affinity for cell membranes. Kojyl-APPA showed no tyrosinase inhibition effect compared to kojic acid in vitro, but showed tyrosinase inhibition effect in situ. It means that kojyl-APPA is converted to kojic acid enzymatically in cells. Kojyl-APPA showed the inhibitory activity on melanin synthesis in mouse melanoma and normal humal melnaocytes and also showed long-lasting stability in comparison with its original form (kojic acid). Kojyl-APPA showed depigmenting effects when applied to UVB-induced hyperpigmentated region of guinea pig skin. Based on these results, kojyl 3-aminopropyl phosphate can be used as a safe and effective ingredient for the brightness and cleanness of skin.

• 한국인터넷방송통신학회논문지
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• 제17권5호
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• pp.199-208
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• 2017

리튬 폴리머 배터리는 높은 안전성, 빠른 충전 및 긴 라이프 사이클 등으로 인해 에너지 저장치(ESS: Energy Storage System), 전기자동차(EVs: Electric Vehicles)등에 채택이 되어 사용되고 있으며, 그리고 현재는 농업용 드론에서 까지 사용이 되고 있다. 그러나 리튬 폴리머 배터리는 과충 방전에는 리튬-이온 배터리 내의 격차구조가 파괴되어 배터리 수명이 줄어들게 되며, 과충 방전을 방지하기 위해 불균등한 셀 전압을 균등 제어 할 수 있는 셀 밸런싱 시스템이 필수적이다. 본 논문은 각 셀의 충 방전할때의 전압차이를 검출하여 불균형된 셀을 확인하여 비선형 시스템에 적합한 퍼지 제어기를 개발하여 적용한 셀별 밸런싱 알고리즘을 제안한다. 본 논문은 농업용 드론의 배터리팩의 셀 밸런싱을 퍼지제어를 하여 셀 간 균등 제어를 위해 설계하였으며, 최종 결과로 셀 간 밸런싱이 잘 되는지 확인하고 자 셀이 2개 있을 때와 6개 그리고 최종적으로 12개의 각 셀 밸런싱이 되는지를 확인하였다. 이는 다른 제품에도 사용할 수 있는지를 실험하고자 하였으며, 확인결과 사용된 셀의 개수와는 관계없이 셀별 밸런싱이 잘 되고 있음을 확인하였다.

• 한국인구학
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• 제26권2호
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• pp.175-195
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• 2003

본 연구는 1990년대 중반 이후 한국 사회변동의 주요 동인의 하나를 지식정보화라고 전제하구 지식의 창조와 사회적 의사결정 과정에서 핵심적 역할을 담당하는 지식정보직업군의 공간적 분포에 대한 분석을 지리정보시스템(GIS)을 이용하여 제시하고 있다. 1995년 및 2000년 인구센서스 자료를 가지고 분석해 본 결과 한국 사회에서 관료제화 및 지식정보화가 지역별로 불균등하게 진행됨에 따라 서울을 포함한 대도시 및 그 주변에서는 지식정보직업군이라 할 수 있는 전문ㆍ기술직과 관리ㆍ행정직의 비중이 높아지는 반면에, 나머지 지역은 여전히 전통적인 직업구성을 보이는 것으로 나타났다. 이러한 분포의 불균형은 대도시 내부에서도 나타났는데, 서울의 경우 지식정보직업군은 강남구. 서초구. 송파구로 집중되고 있는 것으로 나타났다. 직업분포의 이러한 공간적 불균형은 산업사회의 전형적인 결과라 할 수 있으며 지식정보화에 따라 쉽게 반전될 것으로 보이지는 않는다. 그러나 정보기술의 사회경제적인 활용에 대한 적절한 정책적 대응이 이루어진다면 지역적 불균형이나 양극화는 완화될 수 있을 것이다.

• 대한지리학회지
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• 제37권1호
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• pp.15-40
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• 2002

본 연구의 목적은 지역경제와 산업발전에 중요한 역할을 담당하고 있는 수도권을 대상으로 1997년에 실시된 화물 유동량 조사자료를 이용하여 품목별 화물유동의 공간적 패턴을 도출하고, 그 특성을 파악하는데 있다. 본 연구에서 기능지역을 도출하기 위하여 사용한 분석방법은 인자분석이고. 취급된 품목은 화물유동의 60% 이상을 차지하는 3개 품목. 즉 화학공업품. 경공업품. 금속기계공업품을 대상으로 하였다. 연구대상인 수도권의 분석단위는 36개 존으로 구분하였다. 분석결과 대상품목별로 정도의 타이는 있으나, 화물유동의 공간적 패턴이 지역별로 분산되어 있기보다는 특정지역에 과다하게 집중되어 있음을 알 수 있었다. 특히 서울 도착 지향적 특색이 두드러졌다. 유동이 특히 탁월한 지역은 주로 유통시설 분포가 양호한 지역을 중심으로 이루어지지만 일부 그 시설분포가 양호하지 못한 지역도 유동이 탁월한 양상을 보였다. 이는 특정지역을 중심으로 그 시설이 편재되어 있기 때문으로 사료된다.

• 한국전기전자재료학회논문지
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• 제30권8호
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• pp.469-473
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• 2017

We investigated the effect of different thin-film thicknesses (25, 30, and 40 nm) on the electrical performance of solution-processed indium-zinc-oxide (IZO) thin-film transistors (TFTs). The structural properties of the IZO thin films were investigated by atomic force microscopy (AFM). AFM images revealed that the IZO thin films with thicknesses of 25 and 40 nm exhibit an uneven distribution of grains, which deforms the thin film and degrades the performance of the IZO TFT. Further, the IZO thin film with a thickness of 30 nm exhibits a homogeneous and smooth surface with a low RMS roughness of 1.88 nm. The IZO TFTs with the 30-nm-thick IZO film exhibit excellent results, with a field-effect mobility of $3.0({\pm}0.2)cm^2/Vs$, high Ion/Ioff ratio of $1.1{\times}10^7$, threshold voltage of $0.4({\pm}0.1)V$, and subthreshold swing of $0.7({\pm}0.01)V/dec$. The optimization of oxide semiconductor thickness through analysis of the surface morphologies can thus contribute to the development of oxide TFT manufacturing technology.

• 한국기계가공학회지
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• 제18권2호
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• pp.1-6
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• 2019

With the increase in number of the athletic population and elderly demographic, the demand for orthopedic splints, which are used to support a damaged body, has rapidly increased. Current splints mainly consist of inner and outer parts, which are multiple fabrics covered with polyurethane and nonwoven fabrics, respectively. However, the laminated materials with directly applied pre-polymer coating lead to a high defect rate because of the uneven thickness on the surface. Thus, this study proposes an indirect coating method using a precise clearance controller, which enables the even application of the coating material on multiple inner parts while maintaining a constant thickness. In addition, a roll-to-roll (R2R) technique is applied instead of the sewing mechanism to bond the inner and outer materials together and enhance the productivity in the final stage. In the advanced methods, there is a storage tank that contains polyurethane, a clearance controller, and pairs of rollers in the upper and lower rows. To improve the quality of the products and optimize the equipment, three controllable factors are determined: the viscosity of polyurethane, angle of the gap controller and number of pairs of rollers in the R2R system.

• 척추신경추나의학회지
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• 제16권1호
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• pp.91-105
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• 2021

Objectives A case report is a detailed medical description of previously unreported observations or complications of medical conditions, unique use cases of tests, or new side effects. The purpose of this study was to evaluate the quality of case reports published in the Journal of Korea CHUNA Manual Medicine for Spine & Nerves (JKCMSN). Methods Case reports published in the JKCMSN from January 2013 to December 2020 were selected using the Oriental Medicine Advanced Searching Integrated System (OASIS). The quality of the reports was assessed based on the Consensus-based Clinical Case Reporting Guideline Development (CARE) guidelines. Results Sixty case reports that met the inclusion criteria were included in the assessment. Our analysis revealed that 71.42% of the case reports included all the necessary information and their level of reporting was good. However, their scores in the qualitative subdivisions of the reporting level parameters showed that the quality level was uneven. More than 65% of the papers did not report in the following categories: "Keywords," "Patient information," "Timeline," "Diagnostic assessment," "Therapeutic interventions," "Follow-up and outcomes," "Patient perspective," and "Informed consent." Conclusions Our analysis shows that CARE guidelines need to be followed more rigorously to improve the quality of reporting in the JKCMSN. Further efforts are necessary to develop reporting guidelines and evaluation tools relevant to the Korean clinical context.

• 시스템엔지니어링학술지
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• 제18권2호
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• pp.58-74
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• 2022

Deterministic accident analysis plays a central role in the nuclear power plant (NPP) safety evaluation and licensing process. Traditionally the conservative approach opted for the point kinetics model, expressing the reactor core parameters in the form of reactivity and power tables. However, with the current advances in computational power, high fidelity multi-physics simulations using real-time code coupling, can provide more detailed core behavior and hence more realistic plant's response. This is particularly relevant for transients where the core is undergoing reactivity anomalies and uneven power distributions with strong feedback mechanisms, such as reactivity initiated accidents (RIAs). This work addresses a RIA, specifically a control element assembly (CEA) withdrawal at power, using the multi-physics analysis tool RELAP5/MOD 3.4/3DKIN. The thermal-hydraulics (TH) code, RELAP5, is internally coupled with the nodal kinetics (NK) code, 3DKIN, and both codes exchange relevant data to model the nuclear power plant (NPP) response as the CEA is withdrawn from the core. The coupled model is more representative of the complex interactions between the thermal-hydraulics and neutronics; therefore the results obtained using a multi-physics simulation provide a larger safety margin and hence more operational flexibility compared to those of the point kinetics model reported in the safety analysis report for APR1400. The systems engineering approach is used to guide the development of the work ensuring a systematic and more efficient execution.

• 농업과학연구
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• 제49권4호
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• pp.937-948
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• 2022

Agricultural operations are performed in uneven environments by attaching an implement on the 3-point hitch of a tractor. A high load is thus placed on the 3-point hitch, and fatigue and failure of the hitch may occur during agricultural operations. In this study, a dynamic simulation model was developed to predict the load occurring on the eyebolt of a 3-point hitch, which is the main damaged component. The simulation model was developed and validated using agricultural data as simulation input and validation data. The dynamics model was developed using the specifications of a 78 kW class tractor. A measurement system was constructed to measure the simulation input and validation data. The simulation model was validated using a traction load on an eye bolt, which was measured during plow tillage operation. The measurement results showed that the average traction load on the left and right lower link and the top link were 8,099.97, 4,943.06, and 636.11 N, respectively. The simulation results and the measured traction load on the left eyebolt were respectively 610.30 and 597.15 N. The simulation results and measured traction load on the left eyebolt were respectively 1,179.78, and 1,145.06 N. The error between the simulation and measurement data was roughly 2% on the left eyebolt and 3% on the right eyebolt.

• Steel and Composite Structures
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• 제50권6호
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• pp.659-674
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• 2024

Casting Ultra High-Performance Concrete (UHPC) on an orthotropic steel deck and forming a composite action by connectors could improve the steel deck fatigue performance. This study presents the mechanical performance of a proposed post-combination connection between UHPC and steel, which had a low constraint effect on UHPC shrinkage. A total of 10 push-out tests were conducted for static and fatigue performance investigations. And the test results were compared with evaluation methods in codes to verify the latter's applicability. Meanwhile, nonlinear simulation and parametric works with material damage plasticity models were also conducted for the static and fatigue failure mechanism understanding. The static and fatigue test results both showed that fractures at stud roots and surrounding local UHPC crushes were the main failure appearances. Compared with normally arranged studs, group arrangement could result in reductions of static stud shear stiffness, strength, and fatigue lives, which were about 18%, 12%, and 27%, respectively. Compared with the test results, stud shear capacity and fatigue lives evaluations based on the codes of AASHTO, Eurocode 4, JSCE and JTG D64 could be applicable in general while the safety redundancies tended to be smaller or even insufficient for group studs. The analysis results showed that arranging studs in groups caused obviously uneven strain distributions. The severer stress concentration and larger strain ranges caused the static and fatigue performance degradations of group studs. The research outcome provides a very important basis for establishing a design method of connections in the novel post-combination steel-UHPC composite deck.