Earticle

In measuring step for reverse engineering of sculptured surfaces, computer vision system is used to simplify the complicated surface by boundary edge detection method that minimizes the measuring error. The measured data by Coordinate measuring machine is clouded data points of surfaces which is segmented surface using image process. In this research, the measured data is approximated as NURBS surfaces by new suggested algorithm. The position and number of control points, selection of parametric values and compensation of weight factors are proposed. Finally, surface model is simulated and improved resulting performance is obtained.

지상LiDAR는 토탈스테이션에 비해 신속한 측량이 가능하기 때문에 터널의 내공단면 측량을 적기에 수행하고 중심선 오차와 여 미굴량 발생을 최소화할 수 있는 강점을 가지고 있어 지상LiDAR를 이용한 터널의 내공단면 측량 및 계측이 점점 증대되고 있으며 보다 효율적이고 정확한 지상LiDAR 활용을 위한 연구도 활발하게 진행 중이다. 현재 일반적으로 터널의 여 미굴량을 계산할 때 사용되는 양단면 평균법의 경우 기존 측량 방식인 토탈스테이션 및 사진측량 등과의 비교는 많이 이루어졌으나 터널 전체의 3차원 위치정보를 얻을 수 있는 지상LiDAR를 이용하여 터널의 내공단면을 측량 체적 및 여 미굴량을 구할 때 관측간격에 따른 기준이 없는 실정이다. 이에 본 연구에서는 시험터널에 대한 reverse engineering을 실시하여 터널 내공단면 측량 시 터널단면의 체적을 비교하여 가장 합리적인 간격을 결정하고 이 결과를 토대로 현재 설계 데이터가 존재하지 않는 시험터널에 대한 CAD도면을 제작하였다. 또한 지상LiDAR 기술의 정확도를 검증하기 위하여 토탈스테이션과의 비교를 통하여 타겟좌표 정확도, 입사각에 따른 정확도 분석을 실시하였다.

Surveying by using terrestrial LiDAR(Light Detection And Ranging) is more rapid than by using total station which enables tunnel section profile surveying to be done in suitable time and minimize centerline error, occurrence of overcut and undercut. Therefore, utilization of terrestrial LiDAR has increased more and more in section profile survey and measurement field Moreover, studies of terrestrial LiDAR for accurate and efficient utilization is now ongoing vigorously. Average end area formula, which was generally used to calculate overcut and undercut, was compared with existing methods such as total station survey and photogrammetry. However, there are no criteria of spacing distance for calculating overcut and undercut through terrestrial LiDAR surveying which can acquire 3D information of whole tunnel. This research performed reverse engineering to decide optimal spacing distance when surveying tunnel section profile by comparing whole tunnel volume and tunnel volume in difference spacing distance. This result was utilized to produce CAD drawing for the test tunnel site where there is no design drawings. In addition to this, efficiency of LiDAR and accuracy of CAD drawing was compared with targetless total station surveying of tunnel section profile. Finally, error analysis of target coordinate's accuracy and incidence angle was done in order to verify the accuracy of terrestrial LiDAR technology.

A major fair-access issue has arisen regarding situations where a copyright holder attempts to restrict a reverse engineering right by copyright infringement litigation, contractual shrink-wrap licenses or a protective system that defeats the reverse engineering permissible under the "fair-use" doctrine. Reverse engineering computer software is defined as the process of studying a computer program to obtain useful and detailed insight into the functional mechanisms of the work. Reverse engineering commonly involves copying an original program without the permission of a copyright owner. Indeed, the owners seek to prevent reverse engineering by bringing infringement suits, imposing contractual limitations or installing technological impediments. In the United States, the Digital Millennium Copyright Act ("DMCA") provides a software vendor with extra protection for its protective system, and allows reverse engineering only for the purpose of interoperability. The Uniform Computer Information Transactions Act ("UCITA") makes a shrink-wrap license enforceable even if it contains a term prohibiting reverse engineering. These protectionist measures ensure that a copyright holder can dominate the computer software industryby restricting reverse engineering. Although the Computer Program Protection Act in Korea allows a reverse engineering purporting to achieve interoperability as exception, this is still not enough to strike balance between a copyright owner' interest and public rights to access to a copyrighted work. The current trend toward copyright protectionism undermines the copyright balance thus/ the critical question regarding clarification of the reverse engineering right should be answered by policymakers in terms of reconciliation between copyright, contract and competition policy.

한국사회가 고령사회에 진입하며, 노동현장에서 다양한 세대가 공존하는 상황이 증가하고 있다. 본 연구는 기업의 리버스 멘토링(reverse mentoring)을 세대 교류의 차원에서 분석해보고자 하였다. 문헌연구와 인터뷰를 이용한 사례분석을 통하여 국내외 기업의 리버스멘토링 도입목표를 유형화하고, 의도적 표집방법으로 추출된 미국의 A사와 국내의 B사의 사례를 중심으로 리버스 멘토링 프로그램의 성공적인 실행요소를 분석하였다. 분석틀로는 사회교환이론, 조직연령이론, 세대연대이론을 바탕으로 1) 상호이익성 2) 동등한 기여, 3) 지속가능성의 세가지 명제를 제시하였다. 사례분석결과, 리버스멘토링의 도입 목표는 크게 세 가지로 소셜미디어 교육, 기업의 다양성 증진, 젊은 세대의 트렌드 이해로 나타났다. 미국의 A사와 국내의 B사의 경우 상호이익성과 동등한 기여에서는 유사성이 나타났으며 지속가능성의 경우 미국의 A사와는 달리, 한국의 B사에서는 개선의 여지가 있는 것으로 나타났다. 연구 결과, 앞으로 다양한 세대가 공존하는 노동 조직 내에서 리버스멘토링이 세대교류의 성공을 위한 중요한 함의를 제공할 것이라고 기대된다.

As Korean society enters an aged society, there is an increasing situation in which various generations coexist in the workplace. This study aimed to analyze corporate reverse mentoring in light of generational exchange. Through the case study methods using literature research and interviews, we categorized the objectives of starting reverse mentoring programs in domestic and foreign companies, and analyzed the possibility of generational exchange with the cases of company A in the US and B in Korea extracted by purposive sampling. Based on social exchange theory, organizational age theory, and generational solidarity theory, the analysis framework presented three propositions: 1) mutual benefit 2) balanced contribution, and 3) sustainability. As a result of the case analyses, there were three main objectives of introducing reverse mentoring: learning IT/social media, promoting corporate diversity, and understanding new trends in the younger generation. In the case of A company in the US and B company in Korea, there was a similarity in mutual benefit and balanced contribution. However, regarding sustainability, there was room for improvement in company B in Korea unlike company A in the US. We expect that reverse mentoring will provide important criteria for success in terms of generational exchange within organizations where various generations coexist in the future.

본 연구는 최근 들어 DDoS 공격이 단순히 서비스를 방해하는 것에서 벗어나, 다양한 공격 기법을 혼합한 멀티 벡터(Multi-Vector) 공격으로 발전하고 있다. 이러한 멀티벡터 공격은 DDoS 공격과 더불어 악성코드를 감염시켜, 내부 정보 유출 및 좀비PC를 만들어 DDo S 공격용에 활용될 경우에는 기존의 DDoS 공격 및 악성코드 감염에 대한 방어 전략으로는 한계점이 있다. 따라서 본 논문에서는 다양한 방법을 이용한 멀티벡터 공격을 효과적으로 방어하기 위한 Reverse Proxy Grou p과 PMS(Patch Management Server)를 제시하고자 한다.

The objective of DDoS Attacks is to simply disturb the services. In recent years, the DDoS attacks have been ev olved into Multi-Vector Attacks which use diversified and mixed attacking techniques. Multi-Vector Attacks start from DDoS Attack and Malware Infection, obtain inside information, and make zombie PC to reuse for the next DDoS attacks. These forms of Multi-Vector Attacks are unable to be prevented by the exi sting security strategies for DDoS Attacks and Malware Infection. This paper presents an approach to effectively defend against diversified Multi-Vector attacks by using Reverse Proxy Group and PMS(Patch Management Server).

With the development of many display technologies currently applied to them in the field of printed electronics, there have been many researches that high resolution printing for thin and uniform pattern. In this paper, printing ink flow properties in the reverse offset mechanism were simulated. The aim of this research is to expect the ink flow behavior between cliches to make fine pattern by a printing technique which is a reverse offset. The simulation results show that almost the same as the experiments and the flow behavior according to the ink film thickness and printing pressure changes could be expected.

A turbine blade has complex shaped free-form surfaces that can be modelled as surfaces with variable curvature by high-degree polynomials. Industry typically utilizes a turnkey system and special-purpose machine tool to manufacture turbine blades. A turkey system is a closed form design. Users need only input relevant data to this system to manufacture the product directly. However, users are unaware of the internal operation of the system. With rapidly advances in computing technology, commercial CAD/CAM systems can be utilized to design freeform surfaces and generate a tool path for the designed surfaces. This study uses a reverse engineering technology that is used to reconstruct the CAD model for a turbine blade. The prototype is measured by a coordinate measuring machine to obtain the geometrical control data points that are used to generate the CAD model in the UniGraphics (UG) CAD/CAM system. The UG/GRIP (GRaphics Interactive Programming) language is used to generate the cutter location data rather than using the default UG CAM module. A five-axis NC code is acquired by the developed postprocessor and verified by the solid cutting simulation software $VERlCUT^{(R)}$. Real turbine blade machining is performed on a table/spindle tilting five-axis machine tool, demonstrating the effectiveness of the proposed approach.

This paper describes rapid prototyping (RP) and reverse engineering (RE) application for orthopedic surgery planning to improve the efficiency and accuracy of the orthopedic surgery. Using the symmetrical characteristics of the human body, CAD data of undamaged bone of the injured area are generated from a mirror transformation of undamaged bone data for the uninjured area. The physical model before the injury is manufactured from Poly jet RP process. The surgical plan, including the selection of the proper implant, pre-forming of the implant and decision of fixation positions, etc., is determined by a physical simulation using the physical model. In order to examine the applicability and efficiency of the surgical planning technology, two case studies, such as a distal tibia comminuted fracture and an iliac wing fracture of pelvis, are carried out. From the results of the examination, it has been shown that the RP and RE can be applied to orthopedic surgical planning and can be an efficient surgical tool.

This study was executed to investigate the effects of drinking deep sea water treated by reverse osmosis process(RO-DSW) on growth performance, nutrient utilizability, relative weight of lymphoid organs and the concentration of serum immunoglobulin G(IgG) in broiler chickens. A total of 200 one day old broiler chickens(Ross 308) were equally and randomly distributed into 10 ground floor pens(20 chicks per pen, 5 pens per treatment) bedded with rice-husks. The broilers were offered either fresh tap water(Control) or RO-DSW for 28 days(from d 6 to d 33) as the drinking water. The same basal phase 1 diet for first 2 weeks and phase 2 diet for last 2 weeks were offered ad libitum to the birds. The RO-DSW was prepared by diluting 1:20 ratio with deionized water before offering to chickens. The diet for control birds was supplemented with 0.21 % of food-grade salt to satisfy salt need of the birds. Broiler feeding study resulted that there were no differences in amount of water consumption, mortality and FCR between RO-DSW and control chickens. However, feed intake and body weight gain were increased(p<0.05) by RO-DSW drinking. There was no(p>0.05) difference in nutrients utilizability between RO-DSW and fresh water drinking. There were no (p>0.05) differences in the immune response between the control and treatment group. The serum IgG levels were 3.01 vs 2.87mg/ml and the relative weights of spleen, thymus and bursa of Fabricius were 0.23, 0.18 and 0.20 vs. 0.20, 0.17 and 0.14 for RO-DSW vs. control birds, respectively. The immune responses were tended to be improved by RO-DSW drinking. This study showed an improvement in weight gain and feed intake that could be induced by RO-DSW drinking, although it is difficult to explain the reasons of the improvement at this moment. This study implied that RO-DSW could be successfully used as drinking water to broiler chickens.

In order to reconstruct a full 3D human model in reverse engineering (RE), a 3D scanner needs to be placed arbitrarily around the target model to capture all part of the scanned surface. Then, acquired multiple scans must be registered and merged since each scanned data set taken from different position is just given in its own local co-ordinate system. The goal of the registration is to create a single model by aligning all individual scans. It usually consists of two sub-steps: rough and fine registration. The fine registration process can only be performed after an initial position is approximated through the rough registration. Hence an automated rough registration process is crucial to realize a completely automatic RE system. In this paper an automated rough registration method for aligning multiple scans of complex human face is presented. The proposed method automatically aligns the meshes of different scans with the information of features that are extracted from the estimated principal curvatures of triangular meshes of the human face. Then the roughly aligned scanned data sets are further precisely enhanced with a fine registration step with the recently popular Iterative Closest Point (ICP) algorithm. Some typical examples are presented and discussed to validate the proposed system.

Objective: The purpose of this study is to determine the most effective exercise to improve neck alignment and muscle function in university students with forward head posture among neck stabilization exercises (SE), reverse plank exercises (RPE), and neck stabilization exercises combined with reverse plank exercises (SE+RPE). Design: A pre-post intervention study Methods: In this study, 48 university students with a craniovertebral angle of 49 degrees or less were recruited. The selected subjects were randomly assigned to the SE group, the RPE group, and the SE+RPE exercise. The SE+RPE group performed five repetitions of SE and RPE exercises, each with a 30 s hold and 30 s rest. The SE group performed 10 repetitions of SE and the RPE group performed 10 repetitions of RPE, each with a 30 s hold and 30 s rest. To compare before and after the intervention, neck alignment and muscle function were examined. Neck alignment was examined for the craniovertebral angle and range of motion of the neck, and muscle function was examined for the viscoelastic properties of suboccipital and sternocleidomastoid muscles and proprioceptive sensations of neck. Results: There were no significant differences among the three groups (p>0.05), but the SE+RPE group showed significant improvement in neck alignment and muscle function before and after the intervention (p<0.05). Conclusions: The results of this study recommend the selective application of SE+RPE, SE, and RPE depending on the cause of the subject with forward head posture.

"Reverse run" in K-pop refers to the sudden rise in popularity of a fading song, which is often triggered by memetic videos on YouTube. In this study, we argue that this cultural diffusion is possible without resources of giant agencies or fanbases because individuals are loosely and flexibly connected through digital networks. To test this claim, we collected 1,308 YouTube videos and 611,809 comments on them. We then analyzed user engagement with these videos. For the reverse run case, there was an extensive user engagement with memetic videos that covered, mimicked, or remixed idol groups' music videos or media-produced stage footage, which drove virality. This pattern differed from those of other immediate chart-toppers, which often resulted from big agency promotions or strong fan support. This study indicates that memetic videos play a crucial role in the bottom-up cultural diffusion of reverse run by creating a fandom-like phenomenon where individuals could connect through personalized expression.

A geometric compensation of thin-walled molded parts in reverse engineering is presented. Researches in reverse engineering have focused on the fitting of points to curves and surfaces. However, the reconstructed model is not the geometric model because the molded parts have some dimensional errors in measurements and deformation during molding. Geometric information can give an improved accuracy in reverse engineering. Thus, measurement data must be compensated with geometric information to reconstruct the mathematical model. The functional and geometric concepts of the part can be derived from geometric information. LSM (Least square method) is adopted to determine the geometric information. Also, an example of geometric compensation is given to improve the accuracy of geometric model and to inspect the reconstructed model.

this study was conducted to examine the atherogenic effect of high cholesterol diet (experimental diet) that influences changes of lipoprotein cholesterol metabolism and arterial wall. Seven NewZealand white rabbits were fed control diet, an the other 7 rabbits 2% cholesterol diet for 10 weeks. Results obtained from this study are as follows: 1) High cholesterol diet resulted in a gradual increase of plasma total cholesterol level, reaching upto 1422 mg/dl at the seventh week. 2) CETP (cholesteryl ester transfer protein) activity was significantly higher in high cholesterol group (64.9% at the 7th week) than control group (49.3% at the 7th week) during most of the experimental period except the 6th week. 3) The cholesterol supplementation induced fatty liver and a decrease of hepatic HMG-CoA reductase activities (2.1 moles vs. 0.3nmoles) compared to control group. 4) Bands of apo B-100 and apo E in plasma lipoprotein were thicker in high cholesterol-fed animals tan control animals as visualized by SDS-PAGE. 5) Oxidizability of plasma lipoproteins measured in vitro was greater in high cholesterol group tan control group, but vitamin E level higher in control group. 6) he effect of cholesterol feeding for 10 weeks also led to early fatty streaks in aortic intima. High cholesterol feeding was atherogenic to rabbits, an this seems to be mediated through elevated CETP activities that regulate plasma HDL cholesterol level and decrease an efficiency of reverse cholesterol transport in lipoprotein cholesterol metabolism. The enhanced oxidizability of plasma lipoproteins and lowered vitamin E level may also contribute to the formation of faaty streaks in aorta of cholesterol-fed rabbits.

Four olefinic catechols, commonly referred to as urushiol were isolated from the sap of Korean Rhus verniciflua Stokes and had the stronger inhibitory effects on the reverse transcriptase of AIDS. The hexane extract with a inhibitory effects on reverse transcriptase was purified by silica and ODS gel column chronatography. The active compounds were identified by MS and ¹H-NMR as 3-[8'(Z), 11'(Z), 14'-pentadecatrienyl]catechol, 3-[8'(Z), 11'(Z)-pentadecadienyl]catechol, 3-[8' (Z)-penta- decenyl]catechol, and 3-pentadecylcatechol. All of these compounds showed strong inhibitory effects on reverse transcriptase of AIDS, in which 3-pentadecylcatechol exhibited the highest activity(IC50 : 10.87 ㎍/ml).

Objective: The aim of this study is to investigate effective eccentric exercise methods by analyzing gluteus maximus and hamstring muscle activity through various treadmill exercises with differences in speed and stride length. Design: Cross-sectional design Methods: Twenty healthy men were instructed to perform hamstring eccentric exercise with treadmill. Treadmill exercises were performed at speeds of 0.4 km/h, 0.8 km/h, and 1.2 km/h. For each speed, the exercise was conducted at the subject's normal stride length, -10% stride length, and +10% stride length of the normal stride length. EMG (Electromyography) data (% maximum voluntary isometric contraction) were recorded three times from the gluteus maximus, biceps femoris, semitendinosus of participant's and the mean values were analyzed. Results: There was a significant difference in speed for Gluteus maximus, Biceps femoris, Semitendinosus (p<0.05), but there was no significant difference in stride length and interaction between speed and stride length. All muscles groups showed greater activity as the speed increased (p<0.05). Conclusions: Hamstring eccentric exercise with a treadmill shows higher muscle activation as the speed increases and is especially optimized for activating the biceps femoris muscle.

Marginal Zn deficiency is prevalent through the world and yet human zinc status has not been properly assessed due to the lack of a reliable diagnostic indicator. One potential possibility for zinc status assessment using Zn-binding protein, metallothionein (MT)-mRNA, has been proposed. The purpose of the present study was aimed to show whether measurement of mononuclear cell (MNC) MT mRNA, using a competitive-reverse transcriptase-polymerase chain reaction (competitive-RT-PCR) assay, could indicate zinc status in human subjects. In this study, MNC MT-mRNA expression was measured using a competitive-RT-PCR to compare before and after 14 days of zinc supplementation (50 mg Zn/das zinc gluconate). RT-PCR oligonucleotide primers which were designed to amplify both a 278 bp segment of the human MT-2A cDNA and a 198 bp mutant competitor cDNA template from MNCs, were prepared. MT-2A mRNA was normalized by reference to the housekeeping gene, $\beta$-actin, mRNA for which was also measured by competitive-RT-PCR. There was considerable inter-individual variation in MT-mRNA concentration and yet, the mean MT-2A mRNA level increased 4.7-fold after Zn supplementation, as compared to before Zn supplementation. This MT-2A mRNA level was shown as the same pattern and, even more sensitive assay, compared to the conventional plasma and red blood cells (RBCs) Zn assessment in which plasma and RBCs zinc levels increased 2.3- and 1.2-fold, respectively (p<0.05). We suggest that MT competitive-RT-PCR can be a useful assessment tool for evaluating human zinc status.

본 논문은 매우 방대하고 복잡한 실시간 소프트웨어를 이해하기 위한 하나의 방법론과 도구의 개발 연구에 대하여 보고한다. 대부분 본 논문의 저자에 의하여 개발된 이 방법론과 도구는 ARSU(Architecture-based Real-time Software Understanding)과 SRE(Software Re/reverse-engineering Environment)이다. 재공학과정중에 실시간 소프트웨어의 이해한다는 것은 방대한 규모와 복잡성 때문에 일반적으로 매우 어려운 일이다. 그러나 이러한 어려움을 극복하기 위하여 본 논문에서는 architecture에 근거하여 구조적 ${\cdot}$ 기능적 ${\cdot}$ 행위적 측면에서 3차원적인 이해를 가능하게 한다. 이 방법을 통하여 실시간 소프트웨어를 점진적이며 체계적으로 재${\cdot}$역공학할 수 있게 한다. 첫째, 구조적인 관점은 부모－자식간의 관계에 기초한 상하 층충적으로 이루어진 소프트웨어의 전체적 구조, 그리고 명세와 알고리즘 뷰들을 통하여 관측할 수 있다. 여기에서 구조를 구성하는 기본단위는 SWU(Software Unit)이며 이 SWU는 특정 기준에 준하여 추출된다. 이 구조는 상하 또는 그 역방향으로 소프트웨어를 항해(navigation) 할 수 있게 한다. 이는 소프트웨어에 대한 개요와 상세에 관한 정보를 분리하여 상호간에 연관성이 있게 보여준다. 구조의 어떤 단계, 즉 어떤 추상화 단계에서라도 소프트웨어에 대한 기능적 ${\cdot}$ 행위적 대한 정보를 얻을 수 있게 한다. 둘째, 기능적 뷰는 자료와 제어의 흐름, 입력과 출력, 정의와 사용, 변수와 참조 등을 보여준다. 이 뷰의 각 사항들은 소프트웨어에 대한 특정 기능 정보를 제공하여 준다. 셋째, 행위적 뷰는 상태도, IEL(interleaved event list) 등을 들 수 있다. 이 뷰는 소프트웨어에 대한 실행시 동적 성질을 보여준다. 이 뷰들 외에도 각 측면과 뷰들을 위한 기능, 접속, 주석, 코드 등의 다수의 서류들이 제공된다. 본 연구의 가장 큰 장점은 구조를 항해하면서 여러 차원의 정보를 추상화하거나 세부적으로 확장할 수 있는 기능이다. 이러한 기능들은 이러한 실시간 소프트웨어를 이해 할 수 있는 토대를 마련해 준다. 그리고 이러한 장점은 재사용 가능한 요소를 체계적으로 식별하거나 검증할 수 있게 한다.

This paper reports a research to develop a methodology and a tool for understanding of very large and complex real-time software. The methodology and the tool mostly developed by the author are called the Architecture-based Real-time Software Understanding (ARSU) and the Software Re/reverse-engineering Environment (SRE) respectively. Due to size and complexity, it is commonly very hard to understand the software during reengineering process. However the research facilitates scalable re/reverse-engineering of such real-time software based on the architecture of the software in three-dimensional perspectives: structural, functional, and behavioral views. Firstly, the structural view reveals the overall architecture, specification (outline), and the algorithm (detail) views of the software, based on hierarchically organized parent-chi1d relationship. The basic building block of the architecture is a software Unit (SWU), generated by user-defined criteria. The architecture facilitates navigation of the software in top-down or bottom-up way. It captures the specification and algorithm views at different levels of abstraction. It also shows the functional and the behavioral information at these levels. Secondly, the functional view includes graphs of data/control flow, input/output, definition/use, variable/reference, etc. Each feature of the view contains different kind of functionality of the software. Thirdly, the behavioral view includes state diagrams, interleaved event lists, etc. This view shows the dynamic properties or the software at runtime. Beside these views, there are a number of other documents: capabilities, interfaces, comments, code, etc. One of the most powerful characteristics of this approach is the capability of abstracting and exploding these dimensional information in the architecture through navigation. These capabilities establish the foundation for scalable and modular understanding of the software. This approach allows engineers to extract reusable components from the software during reengineering process.

Trade shows are popular venues for marketers’ pre-launch demonstrations of advanced-stage product concepts, and frequently induce buyers to wait for new models rather than purchase current models without delay. In this study, we develop a two-period model to analyze the inter-temporal strategic interactions in a firm’s pricing strategy for the old and new models when a product concept demonstration is utilized. Our analysis focuses on the interplay of product positioning and product concept demonstrations that induces varying degrees of purchase delays and shapes the firm’s dynamic pricing strategy. We show that pre-launch product concept demonstrations increase profits only when the new model has sufficient horizontal or vertical differentiation from the existing model, and that the mechanisms leading to a profitable concept demonstration are quite different between the two types of differentiations. Product concept demonstrations induce greater volumes of delayed purchases at very low or very high levels of horizontal differentiation, exhibiting a U-shaped pattern, and lead to a lower price for the new model in comparison to its absence. We also find that a simpler pricing policy may dominate more complex pricing strategies when the old model continues to be available on the market along with the new model.