디지털 광고 마케팅 성과 평가를 위한 2단계 효율성 측정 모형

김창중,이학연 대한산업공학회 2021 대한산업공학회 춘계학술대회논문집 Vol.2021 No.6

콘테이너 감귤輸送費와 經濟性

金昌中 한국식품과학회 1977 식품과학과 산업 Vol.10 No.2

The Role of SNS Users’ Motivations on SNS Engagement, Social Capital, and Subjective Well-being

김창중,진창현 한국무역연구원 2014 무역연구 Vol.10 No.3

Social network sites (SNSs) have proven within a very short time to serve as important tools for social communication and interaction. The literature on SNS use and user behavior has not adequately addressed the role of user motivations in generating SNS engagement, social capital, or subjective well-being. Based on survey data (N=715) in Korea, the results revealed that SNS users’ motivations played an important role in the formation of SNS engagement as well as in generating social capital. The study found that SNS engagement is mediated by SNS user motivations and social capital building, and also that social capital building and subjective well-being are mediated by engagement and user motivations. Theoretical and practical implications and limitations are discussed.

비동기식 N-심볼 연속 위상 주파수 변조 방식을 위한 비트 인터리브 된 부호화 변조

김창중,이호경,Kim Chang-Joong,Lee Ho-Kyoung 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.3

인터리브 된 레일리 페이딩 채널에서 비동기식 N-심볼 연속 위상 주파수 변조(Continuous Phase Frequency Shift Keying, CPFSK) 방식을 위한 비트 인터리브 된 부호화 변조(Bit Interleaved Coded Modulation, BICM) 시스템을 설계하고 성능을 분석 하였다. 본 논문에서는 BICM의 설계와 성능 분석을 위하여 비동기식 N-심 볼 CPFSK의 기하학적 등가 정규 제곱 거리(Equivalent Normalized Squared Distance, ENSD)를 사용하였다. 특히 비동기식2-심볼 4진 CPFSK 방식을 위한 BICM 시스템을 설계하였으며, 이 시스템 의 성능을 ENSD를 이용하여 분석하고, 모의실험을 통해 검증하였다. We design and analyze the bit interleaved coded modulation(BICM) for noncoherent N-symbol continuous phase frequency shift keying(CPFSK) on the interleaved Rayleigh fading channel. In this paper, we use the equivalent normalized squared distance(ENSD) of noncoherent N-symbol CPFSK to design and analyze the BICM system. Specially, we design the BICM system for noncoherent 2-symbol 4-ary CPFSK, and analyze the performance of the system by using the ENSD. Simulation results are also provided to verify the theoretical performance analysis.

감귤의 수요분석모형 설정과 활용에 관한 연구

김창중 제주대학 기업경영연구소 1984 經營論集 Vol.8 No.1

石炭化學工業의 育成方向에 關한 硏究

金昌中 제주대학교 1984 논문집 Vol.17 No.2

Ⅰ. Research Purpose The study intends to find the priority to development of chemical products derived by coal tar and crude light oil with a view to producing useful information for the future planning of investment in the industry. Ⅱ. Research Method The work for the study consists of a literature review on the general coal tar chemical industry, trends of market structure of coal tar chemical products and production technology of major chemical products derived by coal tar chemical industry. The method applied in this study is originally based on the present status and trend analysis using the data of the literature mertioned above. Ⅲ. Major Findings The priority to development of derived products for the industry in Korea was analyzed on the basis of following five creteria: 1) dependence of raw materials on coal tar chemical industry, 2) economy of scale compared with oil-oriented production process, 3) rate of value added of such derived products, 4) size of domestic market, 5) technical problems of industrialization. The result of analysis was to be showed that the priority to development would be carbon black (CB) and phthalicanhydride (PA) firstly, and other chemical products derived by the industry should be developed subsequently.

特殊鋼의 需要構造分析 및 豫測 : 巨視的 接近法을 中心으로

金昌中 건국대학교 1980 論文集 Vol.12 No.1

Ⅰ. Research Purpose The study intends to forecast the long-term demand of special steel with a view to producing useful information for the future planning of investment in the industry. Ⅱ. Research Methods The work for the study consists of a literature review on demand forecast methods and development of long-term projection model for steel damand. The method applied in this study is originally based on multiple regression analysis using time series data. However, the model in this study is modified and expanded in order for the trend factors to be fully reflected. To deal with the trend factors, the time series data in Korea and Japan are adopted in the establishment of the model. Ⅲ. Data Collection and Processing In the long-term projections, per capita GNP, heavy-industrialization rate, and relative price index of special steel during the 1970-78 period in Korea and the 1958-70 period in Japan are employed as explanatory variables. The CDC Cyber 73 computer at KIST was used to process and analyze the data. Ⅳ. Major Findings 1. The estimated model indicates that the elasticities of percapita special steel demand to percapita GNP, heavy-industrialization rate, and relative price index represent respectively as 1.34, 0.61, and -1.48. 2. As a result of the predictive test for the estimated model, percapita special steel demand in Korea and Japan is well explained by the three explanatory variables mentioned above. 3. Assuming that annual percent changes of percapita GNP, heavy-industrialization rate, and relative price index are 8.0%, 3.3%, and -1.6% respectively during the 1979-91 period, percapita special steel demand in Korea will be annually increased by 15.3 percent. Therefore its total domestic demand is projected to increase from 323,100 tons in 1978 to 495,100 tons in 1981 to 1,110,200 tons in 1986, and further to 2,373,000 tons in 1991.

鐵鋼工業에 있어서 韓ㆍ日間 産業內分業의 動向과 展望에 關한 硏究 : 國際 競爭力의 比較分析을 中心으로

金昌中 제주대학교 1983 논문집 Vol.16 No.2

The Korean government gave the priority to the construction of heavy and chemical industries in 1973, and as a result Korean steel industry has continued to expand in subsequent years, followed by promotion of the construction of new integrated steelworks in Pohang. The initial steps in the construction of POSCO (Pohang Integrated Iron and Steel Company) were taken with the help of technical guidance from Japan. As a result of that guidance Korean steel-making technology began to make advances,and her productivity has been enhanced rapidly. With the rapid improvement of productivity the international competitiveness of Korean steel industry became to be strengthened, and the intra-industry trade of iron and steel products between Korea and Japan has been expanded: the data show that the ratio of net export to the trade of steel products between two countries changed from -93.5% in 1977 to -33.7% in 1981. Various factors can be cited as reasons for the strengthened international competitiveness of Korean steel industry. There is no question that Korean government's domestic economic policies and industrial policies helped. But, equally important, the Korean steel industry (especially POSCO) absorbed and assimilated what it learned from Japan and the other countries, and made advanced operating techniques flourish in the traditional environment of Korean management. In the future, Korean steel industry will seem to be forced to adopt the system of mass production for relatively limited products in order to maintain high rates of operation, to reduce real unit cost with the accumulation of what can be called "production experience", and to acquire quality control techniques and productivity-raising technology from abroad. The adoption of such a system will make possible huge economies of scale that enable Korean steel industry to lower production costs of some carbon steels sufficiently to penetrate Japanese domestic market. Therefore, Korean export of some carbon steels to Japan will be expanded. On the other hand, because of the difficulty of technological transfer of specialty steels and diversification of Korean consumer requirements for steel products in order to enhance their international competitiveness, Korean imports for specialty steels and high quality steel products will be expanded, especially from Japan for the reasons of the geographical access, internationally Japanese comparative advantages of cost competitiveness, and so on. From this view of points, it can be said that the intra-industry trade of steel products between Korea and Japan will be expanded more rapidly, and the deficit of trade for steel products between two countries will be reduced gradually.

OSSB 변조의 비선형성을 고려한OFDM MMoF 시스템의 성능

김창중,이호경 대한전자공학회 2006 電子工學會論文誌-TC (Telecommunications) Vol.43 No.3

Millimeter over Fiber (MMoF) technique modulates millimeter wave signal optically to transmit it through an optical fiber for long distances with small loss. MMoF system usually uses optical single sideband (OSSB) modulation scheme to reduce fiber chromatic dispersion and obtain high bandwidth efficiency. The optical link of MMoF system using OSSB is treated as a nonlinear amplifier, and the AM/AM characteristic function of the amplifier is a Bessel function of the first kind of order 1. In this paper, we investigate the performance of OFDM MMoF system considering nonlinearity of OSSB modulation. We estimate a power of the nonlinear distortion noise to analyze the theoretical bit error rate(BER), and perform a simulation to verify the theoretical BER. Millimeter over Fiber (MMoF) 기법은 저손실로 장거리에 신호를 전송하기 위하여 밀리미터 대역의 신호를 광학적으로 변조하여 광섬유에 실어서 전송하는 기법이다. 이때 광학적 변조 기법으로는 색 분산(chromatic dispersion)이 적고 대역폭 효율이 뛰어난 광학적 단측파대 변조 (Optical Single sideband; OSSB) 방식이 주로 사용된다. OSSB를 사용하는 MMoF 시스템의 광학 연결부는 비선형 증폭기로 취급될 수 있으며, 그것의 AM/AM 특성 함수는 제 1차 제 1종 베셀 함수이다. 본 논문에서는 이를 고려한 OFDM MMoF 시스템의 성능을 알아보았다. 우리는 OFDM MMoF 시스템의 비선형 왜곡 잡음 전력을 추정하여 이론적인 비트 오율(Bit Error Rate; BER)을 분석하였으며, 모의실험을 통해 이를 검증하였다.

고속 레일리 페이딩 채널에 적합한 개선된 초직교 시공간 격자 부호

김창중,허서원,이호경,Kim, Chang-Joong,Heo, Seo-Weon,Lee, Ho-Kyoung 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.9c

초직교 시공간 격자 부호(Super-Orthogonal Space-Time Trellis Codes; SOSTTC)는 직교 행렬의 집합을 확장하여 부호율의 손실 없이 부호 이득과 다이버시티 이득을 동시에 얻는 방법이다. SOSTTC에서 신호 집합 확장은 부호 행렬의 첫째 열을 회전시킴으로써 이루어진다. 기존에 사용된 회전각은 성능 개선보다 신호 성좌의 확장을 피하기 위한 목적으로 선택되었다. 본 논문에서는 고속 레일리 페이딩 채널에서 SOSTTC의 성능을 개선하기 위해 적당한 회전각을 선택하기 위한 설계 요건을 만들었다. 또한, 적당한 회전각을 사용하여 개선된 SOSTTC를 설계하였다. 그리고 모의실험을 통하여 본 논문에서 설계된 SOSTTC가 기존의 SOSTTC 보다 BER 성능 면에서 더 뛰어남을 입증하였다. Super-orthogonal space-time trellis code (SOTTC) uses the expanded set of the orthogonal space-time block code to obtain coding gain and diversity gain without loss of transmit rate. In SOSTTCs, signal set expansions are performed by rotating the first column of the code matrix. The rotating phases used previously were selected to avoid the signal constellation expansion rather than the performance improvement. In this paper, we make a design criterion to select the proper rotating phase to improve the performance of SOSTTCs for fast Rayleigh fading channels. In addition, we design improved SOSTTCs by using the proper rotating phase. Simulation results are also provided to confirm our SOSTTCs are superior to the previous SOSTTCs in the view of BER performance.