• 한국정보통신학회논문지
• /
• 제11권8호
• /
• pp.1558-1563
• /
• 2007

논문은 fractional-N 방식의 주파수 합성기(PLL)를 낮은 차수의 ${\Delta}{\Sigma}$변조기로 더욱 높은 성능의 PLL로 설계하기 위하여 대역폭 가변 방식의 PLL과 ${\Delta}{\Sigma}$방식의 fractional-N PLL의 구조를 합성한 새로운 방식의 PLL을 제안한다. Matla으로 대역폭 가변을 이용한 ${\Delta}{\Sigma}$방식의 fractional-N PLL의 시뮬레이션을 수행하여 제안된 구조의 특성을 관찰하였다. 본 논문의 대역폭 가변 PLL은 HSPICE 0.35um CMOS 공정을 이용하여 시뮬레이션 하였고, 그 결과 제안된 PLL은 빠른 록이 가능하고 fractional spur를 20dB 정도 낮출 수 있었다.

• 식물분류학회지
• /
• 제39권2호
• /
• pp.120-123
• /
• 2009

서울특별시 은평구 불광동의 나지에서 채집한 덩굴해란초(Cymbalaria muralis P. Gaetrn.)를 국내 미기록 귀화식물로 보고한다. Cymbalaria속은 국내에 처음 보고되는 속으로 현삼과에 속하며, 손바닥 모양의 잎을 가지고, 덩굴손은 없으나 땅에 닿는 마디에서 뿌리를 내려 퍼져 나가는 모습이 덩굴에 가까우며, 꽃의 모양에 있어서 뒤편에 거가 있어 현삼과의 다른 식물과 쉽게 구별된다. 국명은 형태를 따라 덩굴해란초로 신칭하였으며 종의 형태적 특징과 그림을 제시하였다.

• Imaging Science in Dentistry
• /
• 제49권2호
• /
• pp.103-113
• /
• 2019

Purpose: Anatomical variations of the external nasal wall are highly important, since they play a role in obstruction or drainage of the ostiomeatal complex and ventilation and can consequently elevate the risk of pathological sinus conditions. This study aimed to assess anatomical variations of the nasal cavity and ethmoidal sinuses and their correlations on cone-beam computed tomography (CBCT) scans. Materials and Methods: This cross-sectional study evaluated CBCT scans of 250 patients, including 107 males and 143 females, to determine the prevalence of anatomical variations of the nasal cavity and ethmoidal sinuses. All images were taken using a New Tom 3G scanner. Data were analyzed using the chi-square test, Kruskal-Wallis test, and the Mann-Whitney test. Results: The most common anatomical variations were found to be nasal septal deviation (90.4%), agger nasi air cell (53.6%), superior orbital cell(47.6%), pneumatized nasal septum(40%), and Onodi air cell(37.2%). Correlations were found between nasal septal deviation and the presence of a pneumatized nasal septum, nasal spur, and Haller cell. No significant associations were noted between the age or sex of patients and the presence of anatomical variations (P>0.05). Conclusion: Radiologists and surgeons must pay close attention to the anatomical variations of the sinonasal region in the preoperative assessment to prevent perioperative complications.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2009년도 춘계학술대회
• /
• pp.690-692
• /
• 2009

PLL은 위상주파수검출기(PFD), 차지펌프(Charge Pump), 루프필터(Loop Filter), 전압제어발진기(VCO), Divider로 구성하고 있는데 본 논문에서는 설계된 차지펌프 PLL을 시뮬레이션을 해보고 그 결과를 정리하고 레이아웃(layout)까지 하였다. 차지펌프 설계에 있어서 전류 부정합, 전하 공유, 전하주입, 누설 전류등을 고려할 필요가 있다. 설계된 차지펌프는 전류 부정합을 감소시키기 위해 전류뺄셈회로를 이용하여 전류 부정합을 감소시켰으며, spurs를 억제할 수 있도록 설계되였다. 설계된 회로는 $0.18{\mu}m$ CMOS 공정 기술을 사용하여 CADENCE사의 specter로 시뮬레이션 하였으며, virtuso2로 레이아웃 하였다.

• 한국기계가공학회지
• /
• 제19권10호
• /
• pp.36-43
• /
• 2020

A marine turning gear is the main auxiliary machine that enables the disassembly of and maintenance on the main engines. In this study, a marine turning gear based on a helical planetary reducer was developed through analysis of a marine turning gear based on a spur planetary reducer. Nonlinear numerical analysis was performed to determine the ideal contact ratio between the sun gear and the idle gear. Based on this, the surface durability, tooth bending strength, and contact ratio were calculated. In addition, the helix direction was selected to utilize the existing bearings. Gears were manufactured based on the helical gear design values, and the turning gear was evaluated using the FTA standards of MAN Co. Ltd. As a result, a lifetime of 3,000 to 5,000 hours was verified, the maximum torque measured was 105kNm, and the efficiency was measured to be 87.4%.

• 한국기계가공학회지
• /
• 제20권8호
• /
• pp.1-10
• /
• 2021

Gears, which rotate and transmit power by interlocking two cogwheels, were invented in BC. They have been used in various systems, including industrial machinery, transportation devices, and living facilities, through the industrial revolution. Regardless of how they are used, gears are a major source of noise and vibration. Many effective measures are being taken to reduce the radiation noise generated from gears, most commonly by lubrication. Lubrication in gear units reduces friction on interlocking gear surfaces, dampening radioactive noise. This can be very useful for quiet gear design if these lubricating damping effects can be reflected in the analytical phase for gear design. This study experimentally confirms the properties of lubricated and non-lubricated radioactive noise by designing a decelerator gearbox and analyzing the radioactive noise characteristics by torque, rotation, and the number of gears using computer analysis.

• 산경연구논집
• /
• 제13권11호
• /
• pp.1-10
• /
• 2022

Purpose: This study measures the influence of facilitating conditions on employees' attitudes towards the adoption of big data analytics by selected medical aid organizations in Durban. In the health care sector, there are various sources of big data such as patients' medical records, medical examination results, and pharmacy prescriptions. Several organizations take the benefits of big data to improve their performance and productivity. Research design, data, and methodology: A survey research strategy was conducted on some selected medical aid organizations. A non-probability sampling and the purposive sampling technique were adopted in this study. The collected data was analysed using version 23 of Statistical Package for Social Science (SPSS) Results: the results show that the "facilitating conditions" have a positive influence on employees' attitudes in the adoption of big data analytics Conclusions: The findings of this study provide empirical and scientific contributions of the facilitating conditions issues regarding employee attitudes toward big data analytics adoption. The findings of this study will add to the body of knowledge in this field and raise awareness, which will spur further research, particularly in developing countries.

• 산경연구논집
• /
• 제14권8호
• /
• pp.9-17
• /
• 2023

Purpose: This study is to examine how modern art museums might develop into resilient, proactive, and adaptive enterprises. That implies that this study seeks to spur meaningful change by analyzing and comprehending the numerous facets of this issue, paving the path for a long-term future for contemporary art institutions worldwide. Research design, data and methodology: To achieve the purpose of this study, the current author has reviewed numerous relevant prior studies systemically. The technique used in this study was meticulously designed to guarantee accurate data collection and analysis, providing a thorough comprehension of the subject. An organized strategy was used, including finding, reviewing, and synthesizing earlier studies. Results: Based on the investigation of the current literature analysis, this study figured out four workable business models that might increase the prosperity of modern art museums. They result from a thorough examination of previous studies and these initiatives center on improving digital presence, enhancing community participation, diversifying revenue streams, and forming powerful alliances and partnerships. Conclusions: In sum, this study concludes that the use and integration of digital technology enable museums to reach a larger audience and open up opportunities for developing cutting-edge, interactive exhibitions that reflect modern patterns of participation and communication.

• 무역학회지
• /
• 제47권4호
• /
• pp.103-124
• /
• 2022

For venturing into international markets, small and medium enterprises (SMEs) have not only emphasized internal resources but entrepreneurial orientation has also become the need of the day due to its significant role in increasing firm's competitive capabilities. Although research indicates that the competitive strategies can significantly impact export performance, minor attention is given to the relationship between entrepreneurial orientation, business competitive strategy and export performance of small and medium enterprises (SMEs). This study scrutinizes the effect of each dimension of entrepreneurial orientation (i.e., innovativeness, risk-taking, and proactiveness) and each of generic competitive strategies (i.e., cost leadership and differentiation) on the export performance of Chinese SMEs. And we investigated the moderating effect of entrepreneurial orientation on the relationship between the competitive strategies and export performance. We surveyed 217 Chinese SMEs through a structured questionnaire. For the data analysis and hypotheses testing, we used AMOS. 27. The findings display that differentiation and cost leadership strategies significantly improve export performance. The innovativeness, risk-taking and proactiveness also spur Chinese SME's export performance. Further we find that adding entrepreneurial orientation significantly improves our model of the relationship between the competitive strategies and export performance. Thus, our study extends the entrepreneurial orientation literature and provides interesting new insights into how entrepreneurial orientation helps firms create more successful export operations.

• 치과방사선
• /
• 제29권2호
• /
• pp.477-491
• /
• 1999

Objectives : To evaluate the anatomic variations of the paranasal sinuses on computed tomographs. Materials and Methods : The author examined the CT images of the paranasal sinuses retrospectively in 500 patients who visited Chonbuk National University Hospital between January 1996 and December 1997. Results : The highest incidence of anatomic variation of the paranasal sinuses in bilateral structures was agger nasi cel1(73.2％), followed by concha bullosa(31.1％), Onodi cell(24.0％), Haller ce1109.8％), maxillary sinus septum(3.0％), paradoxical middle turbinate(2.5％), pneumatized uncinate process(2.0％), and bent uncinate process. The highest incidence of anatomic variation in midline structures was nasal septum deviation(53.2％), followed by nasal septum aerated(29.4％), bulla galli(24.7％) asymmetric intersphenoid septum(22.3％), and nasal septum spur(13.8％). The correlation between anatomic variation and paranasal sinusitis was not found. Conclusions : The results of this study will aid in the diagnosis and treatment of paranasal sinus diseases, especially in the treatment planning before functional endoscopic surgery.