• Fire Science and Engineering
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• v.33 no.2
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• pp.20-29
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• 2019

In this paper, the effect of spontaneous combustion inhibitor on the surface of coal stockpile in coal yard was investigated by numerical analysis. First, the numerical analysis method of the present study was compared with the results of the previous study by analyzing the case where the spontaneous combustion inhibitor was not applied, and the effect of preventing spontaneous combustion by various areas and positions for spraying spontaneous combustion inhibitor was analyzed. As a result, the larger the application area of the spontaneous combustion inhibitor, the more the effect of preventing spontaneous combustion by blocking the oxygen inflow into the coal stockpile, and the greater the effect of the spontaneous combustion prevention when spraying spontaneous combustion inhibitor from the bottom of the coal stockpile. Spontaneous combustion inhibitor should be sprayed effectively, considering the economic aspects, such as manufacturing cost etc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1239-1247
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• 2003

OFDM(orthogonal frequency division multiplexing) communications system is very attractive for the high data rate transmission in the frequency selective lading channel. Since OFDM has high PAPR(peak-to-average power ratio), OFDM signal may be distorted by the nonlinear HPA(high power amplifier). In this paper, we propose the DSI(dummy sequence insertion) method for OFDM communication system. Some sub-carriers are inserted for PAPR reduction. They carry the specified dummy data sequence which are used for only PAPR reduction and do not work as side information like the conventional PTS(partial transmit sequence) or SLM(selected mapping) method. We use the complementary sequence and the combination of the correlation sequence as the dummy sequence. Flipping technique is used for the DSI method to get the effective PAPR reduction. It is important that BER of the proposed method is independent of the damage of the dummy data sequence. And DSI method has better spectral efficiency than the conventional block coding. On the other hand, threshold PAPR method is applied to cut down the processing time. However, this DSI method is not better than the conventional PTS method in the respect of the PAPR reduction performance. The DSI method includes the threshold PAPR lower than the PAPR of the OFDM signal, reduces the processing time and improves the BER performance.

• Management & Information Systems Review
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• v.36 no.3
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• pp.239-254
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• 2017

This study examines the relationship between R&D spending and patent rights, which are suggested by firms as a way to increase their firm value. Specifically, we examine the relationship between research and development costs and patent rights, and see if there are any differences in the influence of two variables on firm value. The period of this study is from 2005 to 2016, and the sample of companies used in the research including the patenting companies is composed of 333 companies in total. The results of the study are as follows. First, the cost of R&D expenditure and capitalized R&D expenditure showed a significant positive correlation with patents. Second, R&D spending did not show a significant relationship with firm value, but patent rights showed a significant positive correlation with firm value. However, firms that spend a large amount of R&D expenditure (RDD), such as research and development expenses, showed a significant positive (+) value and a patent dummy (PATD). Third, in the analysis of the difference between the dummy of research and development and the patent dummy, the enterprise value of a company that invested a lot of patents and research and development expenses was high. The contribution of this study is to examine the relevance of corporate value to R&D investment for patents. On the other hand, there are various variables that can be used as a sample of patents.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.555-561
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• 2019

This study analyzed the shipbuilding structure of House Tangerine over a ten day period and according to the month in Jeju. By estimating and analyzing the price flexibility function of House Tangerine, the aim was to determine if the shipment control can stabilize and increase the incomes of House Tangerine farmers and derive policy implications. The greatest decline in the coefficients of the ten-day price flexibility occurred in the equations from early June to late July. Therefore, the shipment control of House Tangerine is required more during early June and late July. The coefficient of DUM_Q, indicating the year in which the quality of House Tangerine is somewhat deteriorated, was statistically significant and had a (-) sign. The coefficients of DUM_SUK, indicating the year in which Chuseok (Korean Thanksgiving Day) was in October, was statistically significant and had a (-) sign in the middle and late October. The greatest decline in the coefficient of monthly price flexibility function occurred in July, June, and September. Therefore, shipment control is required more in July, June, and September. The (-) signs of the coefficients of DUM_Q and DUM_SUK suggest that the need for shipment control is more important when the quality is less than better quality and that the necessity of shipment control is required more when Chuseok is in October, respectively.

• The Science & Technology
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• v.27 no.6 s.301
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• pp.39-43
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• 1994

UR의 충격이 채 가시기도 전에 GRㆍTR등 새로운 라운드의 파고가 집더미처럼 몰려오고 있다. 선진국의 경제패권ㆍ기술패권주의의 일환으로 무자비하게 다가오고 있는 이들 파고를 지혜롭게 극복하는 길은 무엇일까? 이 일이야말로 우리가 2000년대의 선진국대열에 합류하느냐 아니면 지금보다 못한 중하위권으로 처지느냐의 갈림길이 될 것이다. 국제화ㆍ개방화시대에 대비한 우리 과학기술의 나아갈 길을 모색해 보았다.

• RED RIBBON
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• s.82
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• pp.18-19
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• 2009

엄청난 위협소구로 콘돔 사용을 권장하는 유럽의 광고 몇 편을 소개한다. 에이즈 예방을 위해 콘돔 사용은 필수. 예전에도 콘돔을 쓰지 않는 섹스를 독거미나 전갈과의 섹스에 비유하여 겁을 주거나, 더미인형과외 섹스에 비유하여 바보로 만들거나, 심지어 여성들에게 콘돔 없는 섹스는 당신에게 권총을 들이대는 것과 마찬가지이니 무조건 거부하라고 강요하는 광고를 소개한 바 있다. 에이즈 예방을 위한 콘돔 사용은 아무리 강조해도 지나침이 없으므로 이런 광고들은 계속 나올 것이다.

• Environmental and Resource Economics Review
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• v.8 no.1
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• pp.131-147
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• 1998

본 논문은 시차종속변수를 이용한 우리 나라 원목수요분석을 통해 장기원목수요의 변화를 예측하는 데 그 목적이 있다. 원목수요는 재화의 특성상 파생수요를 전제하여 분석하였다. 분석에서는 1970년부터 1996년까지 27년간의 원목수요 자료를 이용하였다. 원목수요는 1980년대 들어서면서 1970년대와 같은 빠른 증가는 아니지만 지속적으로 완만히 증가하다가 1991년을 정점으로 하향 안정세를 보이고 있다. 분석에서는 적응적 기대모형과 부분적 조정모형을 사용하였다. 1977년에서 1979년까지 원목수요량의 급격한 증가를 설명하기 위하여 모형내에 더미변수를 사용하였다. 설명변수는 원목가격, 더미변수, 파생재화(목재 및 나무제품)의 가격과 시차종속변수를 이용하였다. 분석 결과, 적응적 기대모형은 시차종속변수를 사용해야 할 만큼 유의한 결과를 얻을 수 없었다. 하지만 부분적 조정모형에서는 각 변수의 추정치가 전반적으로 유의하게 나타났다. 특히, 시차종속변수 추정치에 대한 t값이 2.07로 유의하게 나옴으로써 모형의 설명력을 높여 주었다. 부분적 조정모형의 수정계수는 0.74 정도로 나타났다. 부분적 조정모형의 가정하에 2010년까지 매년 원목가격지수 6.7%와 국내 목제품가격지수 5.8% 상승률에 근거한 방법과 원목가격지수 6.8%와 목제품가격지수 5.6%로 전제하여 원목수요를 전망하였다. 그 결과, 원목수요는 지속적으로 상승하는 것으로 나타났다. 일정한 가격상승률을 전제한 예측수요량이 일정한 가격지수의 상승을 전제한 경우보다 높게 나타났다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.7
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• pp.1058-1072
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• 1997

A head-neck complex dummy, for measuring brain pressure and reaction force in the cervical spine was developed for experimental study related in injury mechanism. Dummy comprised aluminium-casted head with water filled cavity for simulating brain and mechanical neck assembled with six motion segments. Several kinds of experiments (compression, bending, cyclic modulus, relaxation and constant velocity profile) for the developed mechanical neck showed that this neck model is biomechanically reliable compared with in-vitro test results. As an application of developed head-neck complex dummy, shock absorbing properties of protective helmet was chosen. The experiments showed that the maximum pressure increment of brain after impact was tolerable compared with the guide line for mild brain injury pressure (25psi). Constrast to this results, the reaction force in the neck was high enough to produce failure in the cervical spine.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.176-183
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• 2015

This research proposes a method to estimate the fatigue life of SSD(solid-state drive) due to the effect of dummy solder ball under forced vibration. A finite element model of the SSD was developed to simulate the forced vibration and a modal testing was performed to verify the developed finite element model. Fatigue life of the SSD under vibration was experimentally determined according to JEDEC standard in which the SSD was excited by a sinusoidal sweep vibration within the narrow frequency band around the first natural frequency until the SSD fails. Basquin's equation was introduced to estimate the fatigue life of the SSD due to the effect of dummy solder balls. It shows that the dummy solder balls are effective elements of the SSD to increase the fatigue life of an SSD by increasing 700 times of the fatigue life of the given SSD.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.12
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• pp.1353-1358
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• 2014

Tremendous amount of dummy packets are generally generated for faking over a wireless sensor network so as to keep the location privacy of nodes on the communication paths against the global eavesdropping. In this paper, a scoped-flooding protocol is designed for transferring data between each source and mobile sink(aka, basestation) where, the only nodes within the scope are allowed to issue dummy packets at every idle time so that the location privacy of the nodes on the paths is kept and the amount of dummy packets is reduced to the extend of the flooding scope. The size of the flooding diameter can be taken into consideration of the privacy level and the communication cost. We design a detailed specification of the protocol and verify several properties.