• 한국정보통신학회논문지
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• 제20권7호
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• pp.1237-1242
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• 2016

본 논문은 병렬 결합선로(coupled-line)와 부채꼴(radial) 개방형 스터브(stub)를 이용한 고조파가 억압된 저역통과 여파기에 대해 제안을 한다. 본 제안한 저역통과 여파기의 특징은 병렬 결합선로의 구조 때문에 고조파가 광대역으로 억압되었다는 결과를 얻을 수 있었다. 저역통과 여파기의 개방형 스터브는 부채꼴로 구성되어 있으며 이는 여파기의 크기를 조절 할 수 있다. 제안한 저역통과 여파기의 크기는 $6.98{\times}7.60mm2$이며 차단 주파수는 2.45 GHz 이다. 분포정수소자(distributed element)로 구성되어 있어 단가면에서 경제적이고 제작이 쉬우며 대량 생산이 가능한 이점이 있다. 또한 광대역 고조파 억압에 대한 대역폭은 128 %이며 여파기의 삽입 및 반사 손실은 각각 1.07 dB 및 19.5 dB를 얻었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1587_1588
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• 2009

In this paper, PCB embedded balanced-to-unbalamced duplexer using coupled LC resonator was introduced for low cost dualband WiMax front-end-module application. In order to obtain the function of bandpass filter and balun transformer, proposed duplexer was configured by using magnetically coupled LC resonator. Out-of-band suppression was enhanced by applying two m-Derived transform circuits to obtain transmission zeros at 2GHz and 4.8GHz. In order to reduce the size of embedded duplexer, BaSrTiO3 (BST) composite high Dk RCC film was applied to improve the capacitance density. This high Dk film provided the capacitance density of 12.2 pF/mm2. The simulation results shows that fabricated duplexer had an insertion loss of 2.9dB and 5.5dB and return loss of 15dB and 16dB for 2.5GHz~2.6GHz and 3.5GHz~3.6GHz, respectively. The maximum magnitude and phase imbalance were 0.01dB and 0.17dB, and 1degree and 2degree in its passband, respectively. The out-of-band suppression was observed approximately 29dB and 40dB below 1.9GHz and over 4.5GHz, respectively. It has a volume of 6 mm $\times$ 7 mm $\times$ 0.7 mm (height).

• 한국환경보건학회지
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• 제37권5호
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• pp.369-375
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• 2011

Objectives: Exposure to hazardous chemicals during pregnancy may result incritical reproductive health outcomes. Indoor residential levels are significant component of personal exposure. The collection of residential exposure data has been hampered by the cost and participant burden of health studies of indoor air pollution. This study utilized a participant-based approach to collect volatile organic compounds concentration from homes. Methods: Four hundred thirteen women were recruited from three major hospitals in Seoul and Gyeongi Provence and 411 agreed to participate. A passive sampler (OVM 3500, 3M, USA) with instructions were given to the participants, as well as a questionnaire. They were asked to deploy the sampler in their homes for three to five days and return them viapre-stamped envelope. Results: Three hundred forty six participants returned the sampler. Among the returned samplers, three hundred samplers satisfied our monitoring quality criteria. The success rate of the monitoring method was 73%. The geometric mean of TVOC level was 429(2) ${\mu}g/m^3$. The TVOC guideline of 500 ${\mu}g/m^3$ was exceeded in 38% of the houses. The residential VOC levels were significantly associated with remodeling of the house. Conclusions: The results suggested that a participant-based sampling approach may be a feasible and costeffective alternative to exposure assessment involving home visits by a field technician.

• International Journal of Computer Science & Network Security
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• 제21권8호
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• pp.141-148
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• 2021

Project management is a current trend of management in the public sphere, based on different principles, methods and tools. The tools include information technologies providing control over time, cost, quality and planning process in order to ensure accountability to interested parties. The goal of the research was to examine the impact of the integration of information systems in project management of the public sphere on the quality of public governance and administration using the example of infrastructure projects involving the private sector in developing countries. The methodology of the research is based on the concepts of "digital-era governance" (DEG), "Information governance" and "project governance" to determine the effectiveness of information systems and technologies in the management of infrastructure projects in the public sphere. The data from the countries with Lower middle income (India, Indonesia, Philippines, Ukraine, Vietnam) and Upper middle income (Argentina, Brazil, China, Colombia, Mexico, Peru, Romania, Russian Federation, Thailand, Turkey) for 1996-2020 were used to study the effects of DEG. The results show two main trends in the countries with Lower middle income and Upper middle income. The first trend is the development of digital governance, the concept of "digital-era governance" through information systems and performance measurement of the governance system, forecasting of investment flows of infrastructure projects, measurement of payback and effectiveness parameters for investment management in the public sector, decision support. The second trend is the existence of systemic challenges related to corruption, social and institutional factors through the development of democracy in developing countries and the integration of NPM similar to developed countries. The confidence of interested parties, especially private investors, in public authorities is determined by other factors - the level of return on investment, risks and assignment of responsibility, probability of successful completion of the project. These data still remain limited for a wide range of project participants, including citizens.

• 대한토목학회논문집
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• 제30권5D호
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• pp.513-522
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• 2010

도시인구 과밀현상, 지상도로교통망 포화 등의 문제를 해결하기 위한 효율적 토지활용방안으로 지하도로교통망, 복합단지, 저장시설 등 다양한 형태의 지하구조물 건설이 증가하고 있다. 본 연구에서는 지하구조물 시공 시 열악한 환경에 적합한 작업자의 3차원 위치와 통신 연락을 위한 현장지원 통합관리시스템 개발의 경제적 타당성 분석을 수행하였다. 본 분석을 위해 터널 및 지하철건설을 대상으로 현장조사 및 작업자 설문조사를 수행하여 현행 지하구조물 건설 현장관리 프로세스 분석, 문제점 파악 및 시스템 도입을 통해 발생할 것으로 예상되는 편익의 정량적 도출을 실시하였으며, 본 시스템 도입으로 발생할 것으로 예상되는 사고감소, 현장관리비 절감, 생산성 향상을 편익으로 추정하고 경제성 분석기법인 편익/비용비(B/C), 순 현재가치(NPV), 내부수익률(IRR)을 활용하여 시스템 도입의 경제적 타당성 분석을 수행하였다. 분석 결과, 편익/비용비는 1.79로 도출되었으며, 순현재가치와 내부수익률은 각 103,423,797원, 47.01%로 산출되어, 본 시스템 도입의 경제성을 확보할 수 있는 것으로 분석되었으며, 변수들의 불확실성을 고려하여 민감도 분석을 실시하였다.

• 한국광학회지
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• 제20권3호
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• pp.143-147
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• 2009

맨체스터 부호로 코딩된 하향신호의 재변조를 이용하여 가입자내에 광원을 필요로 하지 않고 파장 및 전력제어회로를 제거할 수 있어 가입자 장치를 단순화시킬 수 있고, 상하향 데이터간의 비동기가 가능한 비대칭 2.5 Gbps / 622 Mbps의 광가입자 망을 제안한다. 하향 데이터의 형태에 따른 재변조한 상향신호의 평균오차율을 이론적으로 분석하고, 매트랩을 이용한 시뮬레이션에 의해 그 효용성을 분석한다. 제안시스템에서 SNR의 변화에 따라 임계치를 최적치로 설정할 경우 고정된 종래의 광수신기에 비하여 평균오차율이 향상되고, 수신감도도 3 dB 향상된다. 따라서 하향신호의 재변조를 이용한 제안 시스템을 경제적이고 단순구조를 가지는 광가입자 장치에서 비동기 및 비대칭 쌍방향 데이터 전송에 유용한 방식임을 알 수 있다.

• 설비공학논문집
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• 제26권1호
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• pp.1-7
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• 2014

A field test of a 70 kW heat pump system with flue gas heat recovery was performed by an experiment at the Korea Institute of Energy Research. The flue gas is exhausted from a 320 RT absorption chiller-heater in the heating season. Using this flue gas, source water of the heat pump is heated by a condensed-type heat exchanger in the chimney. The operating characteristics of the heat recovery heat pump system were analyzed. Based on the results of the experiments, operating maps were obtained, and an optimum operating range is suggested, in which the return and heat source water temperature are $51^{\circ}C$ and $31^{\circ}C$, respectively. Additionally, economic analysis of this system was conducted and about 50% energy cost savings can be expected in the heating season.

• Strategy21
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• 통권46호
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• pp.29-56
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• 2020

Despite the deep concerns against the DPRK and the harsh sanctions imposed on it, the country renders the sanctions futile by facilitating various illegal trades such as the ship-to-ship transfers of petroleum or coal. Recently, the international community went into paying attention to solve this matter. Among the measures the community can take, "reinforcing the search and inspection of the DPRK related vessels transiting in the high and territorial seas" is the best policy approach to reduce the sanction evasion and provide the international community with considerable bargaining advantages. This measure requires the forceful action by legal enforcement agencies, also known as VBSS. (Visit, Board, Search, and Seizure) It would make the deals prohibited by the UNSCRs (United Nation Security Council Resolutions) less profitable by reducing the expected return on the deals and increasing the cost for them. So, it would make the illegal deals under the table less attractive. The DPRK has been able to render the sanctions futile by exploiting the limitations of the current maritime sanctions. The resolutions are short of being specific about law enforcement, and the PSI (Proliferation Security Initiative) is legally nonbinding. However, if the UNSCRs and the PSI are combined, they can generate a new source of power and exploit the weakness of the DPRK. Noting that the recent UNSCRs stipulated all the legal discussions in the resolutions are confined and applied only to the DPRK, the PSI can target the commercial trade as well as the WMD-related materials in the case of the DPRK's illegal maritime practices. Therefore, the PSI endorsing partners should go beyond mere commitments. They should discuss action plans to implement the maritime interdictions to the extent that they discourage the DPRK and its business partners continuing the illegal activities.

• 한국전자파학회논문지
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• 제13권1호
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• pp.40-46
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• 2002

본 논문에서는 skeleton slot 복사기를 이용하여 GSM 900과 GSM 1800에서 사용할 수 있는 이중대역 안테나를 설계 및 제작하고 측정 결과를 비교 분석하였다. 기본적인 skeleton slot구조에서는 높은 주파수 대역에서 수평 빔폭이 일정치 않고, 정재파비 특성이 좋지 않은 문제점이 있었으나, 급전부와 측면 방사부분의 다중경로 형성 및 절곡 구조를 이용하여 이를 해결하였다. 안테나의 크기는 반사판이 190$\times$190(mm), 복사기는 154$\times$106(mm), 높이는 33 mm로 하여 현재 서비스 사업자들이 주로 사용하는 크기로 구성하였다 구성 재질은 1mm 두께의 알루미늄판을 이용하며, 이를 NCT로 타공 및 절곡하여 제작하였기 때문에 대량 생산 시 단가를 낮출 수 있다. 측정결과 900 MHz 대역에서 13.7 %, 1,800 MHz 대역에서 16.4 %의 -10 dB 반사손실 대역폭을 만족하고, 방사패턴도 대역별로 $\pm$1$^{\circ}$이내의 일정한 양상을 보여 이중대역 안테나로서의 요구를 만족하였다.

• 한국수산과학회지
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• 제55권5호
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• pp.681-687
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• 2022

The government has implemented a policy to promote the use of extruded pellets in sustainable aquaculture by protecting fishery resources and managing the ocean environment. A survey on the production status and the cost of targeting olive flounder Paralichthys olivaceus culture farms in Jeju Island using extruded pellets was conducted. The survey results were used to examine the profitability and economic feasibility of the test farms, as well as the degree of increase in profitability and economic feasibility of the fish farms receiving government subsidies for employing extruded pellets. The economic feasibility was predicted through a sensitivity analysis of prices and production, which are the variable factors when of using the extruded pellets. Using the economic feasibility analysis, the average NPV (Net Present Value) and IRR (Internal Rate of Return) of sample farms were found to be KRW 5.8 billion and 8.9%, respectively. The result of the economic feasibility analysis of the government subsidy showed a maximum average of about 2.3 times higher NPV and a 3.8% increase in IRR in cases where government subsidies were received.