대형 서점의 출⋅폐점이 도서 구입 행태에 미치는 영향

이용관 연세대학교 사회과학연구소 2023 社會科學論集 Vol.54 No.2

대형 서점은 도서 유통 및 소비뿐만 아니라 중소형 서점의 영업권에 큰 영향을 미치기 때문에 서점업의보호와 소비자 후생 측면에서 대형 서점의 출⋅폐점에 대한 다양한 논의와 공적 개입이 이루어져 왔다. 본연구는 대형 서점이 출⋅폐점한 지역에 거주하는 소비자의 과거, 현재, 미래 시점의 도서 구입 비중 정보를제공하는 조사 자료를 활용해 이들의 도서 구입 행태에 대형 서점의 출⋅폐점이 미치는 영향을 이질적 처치고정효과 모형으로 분석하였다. 분석 결과, 대형 서점의 출⋅폐점과 상관없이 도서 구입 비중이 오프라인 서점에서 감소하고 온라인 서점에서 증가하는 경향을 보이며, 이러한 경향은 대형 서점이 출점한 지역보다 폐점 지역에서 더 크게 나타났다. 시점을 분류해 분석한 결과를 보면, 대형 서점의 출점은 일정 시간이 지난후에 중소형 서점의 도서 구입 비중에 영향을 주었고, 대형 서점의 폐점은 시간이 지남에 따라 온⋅오프라인서점의 도서 구입 비중의 증감 폭을 확대시켰다. 대형 서점의 출⋅폐점에 직접적인 영향을 받는 이용자 표본의 도서 구입 비중은 폐점보다 출점에 영향을 더 크게 받는다. 이상의 결과는 첫째, 대형 서점의 출점을 제한하는 생계형 적합업종 지정은 중소형 서점의 영업권 보호에 기여하나 그 효과는 제한적임을 보여준다. 둘째, 오프라인 서점 생태계와 소비자 후생 측면에서 봤을 때 대형 서점의 폐점에 대한 정책적 고려가 필요함을보여준다. 끝으로, 소비자의 도서 구매 행태 변화를 봤을 때, 오프라인 서점의 보호와 경쟁력 확보를 위해서는 대형-중소형 오프라인 서점 간의 경쟁관계보다는 온라인과 오프라인 서점 간의 경쟁관계에 대한 논의가필요함을 보여준다. This study examined the impact of large bookstore openings and closings on book purchasing behavior by using survey data that provides information on the past, present, and future book purchase proportions of consumers living in areas where large bookstores opened and closed, and a heterogeneous treatment fixed effects model. In both regions where large bookstores opened and closed, the proportion of consumers' book purchases tended to decrease in offline bookstores and increase in online bookstores, and this trend was greater in regions where large bookstores opened than in regions where they closed. As a result of analysis by time point, the opening of a large bookstore affected the proportion of book purchases in small and medium-sized bookstores after a certain period of time. In addition, the closure of large bookstores has a greater impact over time by reducing the proportion of books purchased at offline bookstores and increasing the proportion of books purchased at online bookstores. The proportion of book purchases in the sample that used large bookstores that opened or closed was more influenced by store openings than by store closures. The above results provide three implications. First, regulating the opening of large bookstores contributes to protecting the goodwill of small and medium-sized bookstores, but the effect is limited. Second, policy consideration regarding the closure of large bookstores is necessary from the perspective of the offline bookstore ecosystem and consumer welfare. Lastly, it is necessary to discuss the competitive relationship between online and offline bookstores rather than between types of offline bookstores by size in order to protect and strengthen the competitiveness of offline bookstores.

Whole-Body Voxel-Based Personalized Dosimetry: The Multiple Voxel S-Value Approach for Heterogeneous Media with Nonuniform Activity Distributions

Lee, Min Sun,Kim, Joong Hyun,Paeng, Jin Chul,Kang, Keon Wook,Jeong, Jae Min,Lee, Dong Soo,Lee, Jae Sung Society of Nuclear Medicine 2018 The Journal of nuclear medicine Vol.59 No.7

<P>Personalized dosimetry with high accuracy is becoming more important because of the growing interest in personalized medicine and targeted radionuclide therapy. Voxel-based dosimetry using dose point kernel or voxel S-value (VSV) convolution is available. However, these approaches do not consider the heterogeneity of the medium. Here, we propose a new method for whole-body voxel-based personalized dosimetry in heterogeneous media with nonuniform activity distributions—a method we refer to as the multiple VSV approach. Instead of using only a single VSV, as found in water, the method uses multiple numbers (<I>N</I>) of VSVs to cover media of various density ranges, as found in the whole body. <B>Methods:</B> The VSVs were precalculated using GATE Monte Carlo simulation and were convoluted with the time-integrated activity to generate density-specific dose maps. CT-based segmentation was performed to generate a binary mask image for each density region. The final dose map was acquired by the summation of <I>N</I> segmented density-specific dose maps. We tested several sets of VSVs with different densities: <I>N</I> = 1 (single water VSV), 4, 6, 8, 10, and 20. To validate the proposed method, phantom and patient studies were conducted and compared with the direct Monte Carlo approach, which was considered the ground truth. Finally, dosimetry on 10 patients was performed using the multiple VSV approach and compared with the single VSV and organ-based approaches. Errors at the voxel and organ levels were reported for 8 organs. <B>Results:</B> In the phantom and patient studies, the multiple VSV approach showed significant decreases in voxel-level errors, especially for the lung and bone regions. As the number of VSVs increased, voxel-level errors decreased, although some overestimations were observed at the lung boundaries. For the multiple VSVs (<I>N</I> = 8), we achieved a voxel-level error of 2.06%. In the dosimetry study, our proposed method showed greatly improved results compared with single VSV and organ-based dosimetry. Errors at the organ level were −6.71%, 2.17%, and 227.46% for single VSV, multiple VSV, and organ-based dosimetry, respectively. <B>Conclusion:</B> The multiple VSV approach for heterogeneous media with nonuniform activity distributions offers fast personalized dosimetry at the whole-body level, yielding results comparable to those of the direct Monte Carlo approach.</P>

Theoretical Prediction Model for Surface Settlement Caused by the Excavation of New Tunnels Undercrossing Existing Tunnels Based on Modified Stochastic Medium Theory

Qiang Xu,Shengxiang Lei,Yongquan Zhu,Wei Zhao,Cong Wang,Dapeng Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.9

The deformation pattern of the stratum caused by constructing a new metro tunnel crossing an existing tunnel is different from the deformation pattern caused by general tunnel construction. However, the prediction results by the ordinary surface settlement prediction model often bring significant errors because the complex influence of existing tunnels on the surface settlement caused by the excavation of new tunnels is always neglected. Based on the equivalent layered method and stochastic medium theory, a prediction model for the surface settlement due to excavating a new tunnel under an existing tunnel in the heterogeneous stratum was established. By equating the bending stiffness of an existing tunnel before and after applying the equivalent layered method, the layer index was determined. The critical parameters of the stochastic medium theory were derived based on the relationship between the critical parameters of both the Peck empirical formula and the stochastic medium theory. The surface settlement of some typical projects was predicted and compared by the prediction model in this paper and the ordinary prediction model. The comparison shows that the proposed prediction model and parameter determination method in this paper had high accuracy and applicability. The results of the prediction model in this paper fit the results of numerical calculation. The research of this paper can provide a new method for the theoretical prediction of surface settlement caused by the excavation of a new tunnel under an existing tunnel in the heterogeneous stratum and the determination of critical parameters of the stochastic medium theory.problem in the construction industry, and helps reducing the material waste and budget cost.

비균질체의 혼합상태에 대한 Walsh해석과 응용

박진무 대한기계학회 1986 대한기계학회논문집 Vol.10 No.1

본 연구에서는 구성원의 분포를 명확히 지시하는 체적 distribution을 기본 으로하고 Walsh 해석을 적용하므로서 혼합상태를 일련의 수치로 표시한다.이변환 과정에서 정보량의 분포가 변하는 현상을 고찰한 후 그 특징을 비균질체의 단순한 형태인 다공성고체의 체적변화거동에 응용하여, 현재 통용되는 구형모텔해석의 이론 적 근거를 밝힌다. Walsh analysis is applied to the numerical specification of the volume distribution which is the key parameter in the formulation of the constitutive equations of heterogeneous media, indicating the geometrical state of the mixture. An example of two-dimensional volume distribution, its approximation, and the Walsh correlation coefficients are presented and the change of the information distribution in the operations is investigated. The phenomena of information concentration upon the large-scale Walsh coefficients are applied to the volumetric response of porous slids, clarifying the validity of the spherical-model calculation.

분산이질환경에서 중소기업형 FMS공유구조에 대한 연구

박제웅(JE-WOONG PARK),김원중(WON-JUNG KIM) 한국해양공학회 2003 韓國海洋工學會誌 Vol.17 No.5

A practical method to investigate the sharing architecture of FMS, for small and medium enterprises, on distributed heterogeneous environmental conditions is investigated. Because the industrial FMS model requires a reasonable size for actual work-site flexible operation, the initial facility expense is very heavy. The support for flexible cooperation of FMS, with some external different FMS, can reduce expenditures and provide greater functionality. While most FMS provide their operation process using an adequate mechanism, when used in isolation, such as island of automation, there is increasing demand for FMS that can cooperate. By exchanging intermediate products and information with other external FMS, products can be produced that cannot be produced alone, such as those that require various processes. This study first considers the sharing architecture of FMS for small and medium enterprises, and investigates the effects of the general sharing architecture of FMS on distributed heterogeneous environments, by using transducer approach to agentification. In this study, set-up station or in-out station takes charge of the gateway of intermediate products, and routes them among distributed heterogeneous FMS plants. The transducer approach is applied to web agent and set-up agent established interfaces, with system controller and setup controller. In this study, the FMS-established sharing architecture is able to obtain not only the internal flexibility, but also the external flexibility.

Evidence for the importance of particle distribution in effective medium theory: a model study

진재식,이준식 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.8

This study investigates the fundamental effects of particle distribution in a heterogeneous composite, which has never been revealed before. This work is based on the Laplace equation in cylindrical coordinates and shows that the effective thermal conductivity has a different value even at the same volume fraction depending on the particle distribution configuration. Consequently, applying the effective medium approximation without using detailed information about the particle spatial distribution can result in considerable error. This is especially true for the case of augmented conduction by insertion particles.

Homogenization for fissured medium equations

박희철 충청수학회 2008 충청수학회지 Vol.21 No.1

We introduce the homogenized dierential systems forssured medium equations representing the small temperature vari-ation or densities of a uid in a system consisting of two compo-nents.

INCOMPRESSIBLE NAVIER-STOKES EQUATIONS IN HETEROGENEOUS MEDIA

Pak, Hee Chul 충청수학회 2006 충청수학회지 Vol.19 No.4

The homogenization of non-stationary Navier-Stokes equations on anisotropic heterogeneous media is investigated. The effective coefficients of the homogenized equations are found. It is pointed out that the resulting homogenized limit systems are of the same form of non-stationary Navier-Stokes equations with suitable coefficients. Also, steady Stokes equations as cell problems are identified. A compactness theorem is proved in order to deal with time dependent homogenization problems.

기업 혁신이 수출에 미치는 영향 -국내 중소기업을 중심으로-

강석민 한국기업경영학회 2012 기업경영연구 Vol.19 No.2

Exporting to firms has been identified as a fundamental and strategic way to enter into foreign markets. According to stage theory of internationalization suggested by Johanson and Vahlne (1977), a firm does exporting as the first strategy to enter into foreign markets and gradually expands foreign markets. Even though a firm goes to foreign markets by direct investing, it still do exporting. Therefore, the relationship between direct investment and exporting to a firm may be complementary. As a result, many studies have focused to find the determinants of exporting. In general, firm innovation has been largely acknowledged as a crucial factor in a strategic aspect in Korean small and medium sized firms. Although Korean small and medium sized firms have limited resources, they tend to improve firm innovation to survive rapidly changing business environments in various foreign markets. Using 305 small and midium sized Korean venture firms listed on KOSDAQ over the periods from 1999 to 2010, this study examine the effect of firm innovation on export. In general, R&D expenditure can’t be a proper proxy variable for firm innovation. Unlike the previous studies, this study tried to investigate the effect of firm innovation on export, using innovation performance of firms from a Cobb-Douglas function. The empirical results indicate that firm innovation is positively associated with export. And the same results were shown when controlling for individual firm heterogeneity, heteroscedasticity and autocorrelation of an error term, and firm innovation of the previous year. The empirical results mean in general that firms extending the process of foreign entry through export need to improve firm innovation. Although this study finds the positive association between firm innovation and export, there are problems in this study. First, this study only considers exporting of firms as one of the ways for foreign market entry. Even though Korean small and medium sized firms listed on KOSDAQ have a large portion of exporting, they could also consider other ways to enter into foreign markets. Therefore, it is needed to think about other ways to enter into foreign markets as well as exporting. Second, this study employs innovation performance made from a Cobb-Douglas function. In other words, this means we cannot know from where firm innovation performance is coming. Therefore, a future study which can be suggested should consider a multiple aspects of firm innovation. For example, OECD Olso Manual (2005) suggested four types of firm innovation such as product innovation, process innovation, marketing innovation, and organizational innovation. Accordingly, it is needed to examine the relationship between an individual type of firm innovation and exporting in a future study, if the related data are available. This direction of a future study can tell which effort for innovation is required to firms. 기업의 혁신은 기업의 전략 측면에서 중요한 요인으로 간주되어 오고 있다. 국내 중소기업들은 자원의 한계에 직면해 있음에도 불구하고, 해외진출을 통하여 기업의 성과를 달성하고 있다. 본 연구는 1999년부터 2010년까지 코스닥(KOSDAQ)에 상장된 305개의 국내 중소기업들을 대상으로 기업의 혁신성과가 수출에 미치는 영향에 대해서 분석하였다. 일반적으로 기업의 혁신과 관련하여 R&D 지출이 대리변수로써 사용되어져 왔으나, R&D 지출은 혁신을 위한 투입요소이지 혁신의 직접적 대리변수가 될 수 없는 등의 한계점을 지니고 있다. 따라서 기존의 R&D를 사용한 연구와는 달리 콥-더글라스(Cobb-Douglas) 생산 함수로부터 혁신성과를 도출하여 국내 중소기업의 수출에 미치는 영향에 관하여 분석을 시도하였다. 실증 분석의 결과는 기업혁신이 수출에 유의적인 정(+)의 영향을 제공하고 있음을 제시하고 있다. 이러한 기업 혁신의 영향은 각 기업의 이질성, 오차항의 이분산과 자기상관성, 전년도의 기업의 혁신성과를 고려한 다양한 통계 기법을 사용하였을 때 역시 유의적인 양(+)의 영향을 미치고 있음을 보여주고 있다. 본 연구의 실증분석 결과로부터 수출을 통한 해외진입을 추구하는 기업들은 혁신성과를 향상시킬 필요가 있음을 시사하고 있다

A Study on the Effective Hydraulic Conductivity of an Anisotropic Porous Medium

Seong, Kwanjae The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.7

Effective hydraulic conductivity of a statistically anisotropic heterogeneous medium is obtained for steady two-dimensional flows employing stochastic analysis. Flow equations are solved up to second order and the effective conductivity is obtained in a semi-analytic form depending only on the spatial correlation function and the anisotropy ratio of the hydraulic conductivity field, hence becoming a true intrinsic property independent of the flow field. Results are obtained using a statistically anisotropic Gaussian correlation function where the anisotropy is defined as the ratio of integral scales normal and parallel to the mean flow direction. Second order results indicate that the effective conductivity of an anisotropic medium is greater than that of an isotropic one when the anisotropy ratio is less than one and vice versa. It is also found that the effective conductivity has upper and lower bounds of the arithmetic and the harmonic mean conductivities.