Recently, deep learning that is the most popular and effective class of machine learning algorithms is widely applied to various industrial areas. A number of research on various topics about structural engineering was performed by using artificial neural networks, such as structural design optimization, vibration control and system identification etc. When nonlinear semi-active structural control devices are applied to building structure, a lot of computational effort is required to predict dynamic structural responses of finite element method (FEM) model for development of control algorithm. To solve this problem, an artificial neural network model was developed in this study. Among various deep learning algorithms, a recurrent neural network (RNN) was used to make the time history response prediction model. An RNN can retain state from one iteration to the next by using its own output as input for the next step. An eleven-story building structure with semi-active tuned mass damper (TMD) was used as an example structure. The semi-active TMD was composed of magnetorheological damper. Five historical earthquakes and five artificial ground motions were used as ground excitations for training of an RNN model. Another artificial ground motion that was not used for training was used for verification of the developed RNN model. Parametric studies on various hyper-parameters including number of hidden layers, sequence length, number of LSTM cells, etc. After appropriate training iteration of the RNN model with proper hyper-parameters, the RNN model for prediction of seismic responses of the building structure with semi-active TMD was developed. The developed RNN model can effectively provide very accurate seismic responses compared to the FEM model.

구조물의 진동에 의해 유발되는 사용성, 안정성 저하를 방지하고, 성능을 개선하기 위하여 많은 진동제어시스템이 사용되어 왔다. 제어기 설계가 H2-norm, H∞-norm 으로 분리되어 독립적으로 이루어지다가 LMI 기법에 의하여 보다 효율적인 제어기 설계가 가능하게 되었다. 본 연구에서는 관심지점의 구조물 응답을 특정한 값 이하로 보장한 상태에서 제진장치 구동에 필요한 변수를 최소 화하는 제어알고리듬을 개발하여 능동형뿐만 아니라 수동형제진장치에도 적용하는 방안을 제시하였다. 관심지점의 구조물 응답의 제한은 요구 등가감쇠비와 H∞-norm을 연계하여 구속조건으로 설정하고 목적함수는 제진장치의 이송거리 또는 댐퍼 용량은 H2-norm으 로 표현하는 혼합제어를 구성하였다. 본 연구에서 제안된 혼합제어 기법을 능동질량감쇠기와 등가치환 점탄성 댐퍼가 설치된 구조물에 적용하여 수치적으로 검증하였다. 수치해석결과, 혼합제어문제를 LMI표준형으로 전환하면 능동형, 수동형 제진장치 설계를 보다 용이하게 적용 가능함을 알 수 있었다.

바람하중을 받는 고층건물의 진동을 저감하기 위한 다양한 진동제어장치가 적용되어왔다. 제어의 주된 목적은 구조물의 응답을 저감하는 것이지만 효율적인 제어력의 산정 또한 중요한 설계요구사항중의 하나이다. 능동형제진장치를 중심으로 제어력 산정은 크게 시스템의 H2, H∞-norm을 분리하여 독립적으로 결정되어 왔다. 보다 효율적인 제어력 산정을 위해서 두 가지 norm을 혼합한 제어알고리듬이 개발되었고 이를 LMI 표준형으로 변환하여 보다 용이하게 최적 해를 제공하게 되었다. 본 연구에서는 제어 후 구조물의 요구 등가감쇠비를 H∞-norm을 이용하여 구속하고 제어력만을 별도로 H2-norm을 이용한 제어알고리듬을 개발하여 능동형뿐만 아니라 수동형제진장치에도 적용하는 방안을 제시하였다. 본 연구에서 제안된 혼합제어 기법을 능동질량감쇠기와 카고메 트러스 댐퍼가 설치된 구조물에 적용하여 수치적으로 검증하였으며, 수치해석 결과로부터 능동형뿐만 아니라 수동형제진장치설계를 LMI표준형으로 전환하는 기법을 적용하면 제어이득뿐만 아니라 감쇠용량도 효율적으로 산정 가능함을 알 수 있었다.

In this study, the retractable-roof spatial structure was chosen as the analytical model and a tuned mass damper (TMD) was installed in the analytical model in order to control the seismic response. The analysis model is mainly consisted of runway trusses (RT) and transverse trusses (TT), and the displacement response was analyzed by installing TMD on those trusses. The mass of the single TMD which is installed in the analytical model was set to 1% of the total structure mass and the total TMD mass ratio was set to be 8% or 6%. In addition, the mass of a single TMD was varied depending on the number of installations. As a result of analyzing the optimal number of installations of TMD, the displacement response was reduced in all cases compared to the case without TMD. Above all, the case with 8 TMDs was the most effective in reducing he displacement response. However, in this case, as the load on the upper structure of the retractable-roof spatial structure increases, the total mass ratio of TMD was maintained and the number of TMDs was increased to reduce the mass ratio of one TMD.

In the precedent study, the retractable-roof spatial structure was selected as the analytical model and a tuned mass damper (TMD) was installed to control the dynamic response for the earthquake loads. Also, it is analyzed that the installation location of TMD in the analytical model and the optimal number of installations. A single TMD mass installed in the analytical model was set up 1% of the mass of the whole structure, and the optimum installation location was derived according to the number of change. As a result, it was verified that most effective to install eight TMDs regardless of opening or closing. Thus, in this study, eight TMDs were installed in the retractable-roof spatial structure and the optimum mass ratio was inquired while reducing a single TMD. In addition, the optimum mass distribution ratio was identified by redistributing the TMD masses differently depending on the installation position, using the mass ratio of vibration control being the most effective for seismic load. From the analysis results, as it is possible to confirm the optimum mass distribution ratio according to the optimum mass ratio and installation location of the TMD in the the retractable-roof spatial structure, it can be used as a reference in the TMD design for large space structure.

본 연구에서는 DVR 내부 공기유동을 직접 제어하여 CPU의 온도를 낮추기 위한 유동제어 구조물을 제안하였다. 제안된 구조물은 세 개의 얇은 판의 형태로 구성되었으며, DVR 내부의 공기 유동을 포괄적으로 제어하여 CPU의 효율적인 방열을 유도하고자 하였다. DOE와 RSM을 이용한 매개변수 연구기법을 통해 유동제어 구조물의 형상을 최적화하였으며, 해석에는 유한체적방법을 이용한 유체역학 분석 패키지인 FlowVision을 사용하였다. 실제 DVR 기기에서의 실험을 통해 해석 결과를 검증한 결과 CPU의 온도가 16.1℃ 낮아짐을 확인하였다

Introduction In the past study, the relationship between the power structure of marketing and research and development (R&D) and NPD performance was not consistent (Atuahene-Gima & Evangelista, 2000; Engelen & Brettel, 2012; Li & Atuahene-Gima, 1999, 2001). The inconsistency may result from each study in different industrial contexts. It reflects every NPD project faces different environmental uncertainties. Furthermore, we adopt the external control perspective to glue power structure and NPD performance under a certain external environment together. Therefore, this paper tends to fulfill the gap of prior study, and the main objective of this research is to investigate whether the power structure of marketing and R&D functions have different linear relationships under the different level of environmental uncertainty. A NPD team is like a cross-functional organization that the NPD team is composed of multiple functions, and it has independent budgets. The members in the team will allocate their limited resources like budgets or positions to respond environments and to maximize profits. Theoretical Development When a NPD team faces the high market uncertain situation, marketing function can gather more resources because of its own power. Thus, R&D members in a NPD team may have less determination in the process of NPD. Even though they create a new product, marketing specialists make most decisions in the NPD team. According to function’s contribution argument, the more contribution of a certain function to the NPD process, the more positive related to the new product success (Atuahene-Gima and Evangelista, 2000; Atuahene-Gima and Luca, 2008; Li and Atuahene-Gima, 1999). Therefore, the current study proposes the hypothesis1 described below: H1: Market uncertainty will strengthen the relationship between power structure leaned to marketing and NPD successes. When a NPD team encounters the fast technological change situation, R&D function has more resources because of power. New product teams, however, usually have scare resources, so that another important function like marketing will have fewer resources than R&D function. Thus, marketers in a NPD team may have less determination in the process of NPD. The marketers may have some influence on launch stage like sales and promotion or distribution channels (Hsieh et al., 2008), but R&D specialists make most decisions in a NPD team. Therefore, the current study proposes the hypothesis2described below: H2: Technological uncertainty will strengthen the relationship between power structure leaned to R&D and NPD successes. Eisenhardt and her colleagues indicated that the organizations in high velocity environments have better performance when they decentralize the power structure (Eisenhardt, 1989; Eisenhardt and Bourgeois, 1988). They also described that this firm tended to introduce a new product line, and that its channel partners were fighting with each other by price wars but the dominant marketing function did not have enough time to perform its regular job. To maintain its power and resources, the dominant function may highlight its importance, so it will withhold external information and enable other members to perceive the external environment what dominant function expect them to perceive. When organizations find a lot of environmental changes, it is too late. Therefore, in the beginning organizations adopted decentralized power structure, and allocated resources equally. The members in organizations may not snatch resources, so they may not take political actions also. For the specialists in new product development team, they could not control their unique knowledge to withhold the information and to satisfy their own self-interests. Therefore, the relationship between marketing and R&D power distribution in a NPD team and new product financial performance is weakened in high velocity environments (Eisenhardt and Bourgeois, 1988). The hypothesis3 in the current study is below: H3: the relation between the power distribution in new product development teams and new product development successes is inverted U curve under the high technological and market uncertainty. Coping environment could rely on top manager’s backgrounds like marketing, technology or finance (Hambrick and Mason, 1984). To maintain the status of the dominant function, the dominant function will lead the organization to identify the important problems related to its function. In order to ensure keeping their power, moreover, the dominant function could institute some regulations or create norms. According to resource dependence perspective, if an organization has higher the formalization of power, the dominant function could gather more resources because of legitimacy. Further, the higher formalization of power may strengthen the relationship between power distribution and performance. Thus, our hypothesis 4 is below: H4: Under the higher formalization of power in a new product development team, the stronger relationship between the marketing and R&D power distribution and new product performance than under the lower degree of formalization of power situation. Research Design The current study used questionnaire survey and purposive sampling method to collect data. In order to eliminate the bias of common method variance (CMV), this study conducted multiple sources including project managers, the member charging marketing, and the member charging R&D to administrate questionnaires differently. In order to avoid selection bias, this study, moreover, asked the informants select the most recent new products developed and launched for minimum of twelve months. We sent three types of questionnaires to project managers, the member charging marketing, and the member charging R&D respectively. The current study sent questionnaires to 112 firms, and 69 firms are returned. The response rate is 61.61%. At new product level, there are 207 new product projects, and 100 firms are returned. The response rate is 48.31%. We also do tests of bias due to nonresponse which were conducted by using a comparison of early to late respondents’ all variable means (Armstrong & Overton, 1977). No evidence of a bias was found. The current study applied Moorman’s (1995) operationalization of new product performance is that the extent to which the product has achieved the objective of market share, sales, return on assets, profit margin, and return on investment during the first 12 months of its life in the marketplace. These items were used a 7-point Likert scale where 1 was “low” and 7 was “high”. This research adopted Homburg et al. (1999) scale to measure the power structure between marketing and R&D functions by using 100-point constant-sum scale for each NPD issue, and other previous studies also used issue-based perceptual power scale (Enz, 1989; Hinings et al., 1974; Pfeffer, 1981; Verhoef and Leeflang, 2009). The current study adopted Jaworski and Kohli’s (1993) scale to measure market and technological turbulence. The items were used a 7-point Likert scale where 1 was “extremely disagree” to 7 was “extremely agree”. In order to rule out other effects, we controlled industrial category, firm age, the number of marketing and R&D members involved in the NPD process, environmental hostility. Result and Conclusion The first finding is that under low market uncertainty and high technological uncertainty, balance of power structure tends to swing to the side of R&D function, and achieve better in NPD performance. Take IC design of High-tech industry as an instance, NPD project ends to perform better when the balance of power structure swing to the side of R&D function. The second finding is that under high market uncertainty and low technological uncertainty, NPD formalization helps to strengthen the relationship between marketing and NPD performance. Take frozen dessert in the food industry or leisure and sports fabrics in the textile industry as examples, formalization of NPD process can help marketing-driven NPD projects perform better in market. These findings advanced the understanding of the relationship between the power structure of marketing and R&D and NPD performance, rather than focusing on a single function, marketing or R&D. Furthermore, examining the relationship between the power structure of marketing and R&D and NPD performance in different environment uncertainty situations explained the inconsistency of the relationship between the power structure of marketing and R&D and NPD performance in past studies. Finally, this research conditionally supported the moderating effect of NPD formalization on the relationship between the power structure of marketing and R&D and NPD performance, and this exploration never been found.

수분을 포함한 압축공기는 공압 시스템에서 부식과 관석 등의 여러가지 문 제를 유발하기 때문에 기상 내의 수분을 효율적으로 제거하기 위한 다양한 기술이 개발되어오고 있다. 특히, 분리막을 이용한 제습 방법은 에너지 소비가 작 고, 장치를 소형화할 수 있다는 장점으로 주목받고 있다. 본 연구에서는 제습용 중공사막을 상전이 방적법으로 제조하고, 친수성 또는 소수성으로 표면 개질하였다. 선택도와 투과도 향상을 위하여 기공 구조를 제어하였으며, SEM, 기체 투 과도, 접촉각 측정 등으로 중공사막의 특성을 분석하였다. 또한, 분리막을 모듈 화하여 제습 실험을 수행하였으며, 여러 운전 조건에서의 특성을 확인하였다.

구조물의 성능을 개선하기 위하여 다양한 진동제어장치가 사용되고 있다. 대부분의 제진장치는 구조물의 감쇠비를 증가시킴으로써 성능개선효과를 유도하기 때문에 증가된 감쇠비는 제진장치에 의한 구조물의 성능을 평가하는 중요한 지표가 될 수 있다. 본 연구에서는 강풍 등으로 제진장치가 운영 중인 상태에서 구조물의 응답만을 이용하여 각 모드에 증가된 등가감쇠비를 추정하는 프로세스를 개발하고 이를 성능개선효과를 평가하는데 활용하고자한다. 제진장치가 설치된 구조물은 비고전 감쇠시스템이므로 상태공간 모드분해법을 이용하여 계측응답으로부터 모드 응답을 구하고, 분해된 모드응답에 가상 동적 진동기를 적용하여 각 모드에 증가된 감 쇠비를 구하였다. 제안된 제진장치 설치 구조물 감쇠비 추정법을 검증하기 위하여 수동형 제진장치로 카고메 점탄성 댐퍼를, 능동형 제진장치로 능동질량감쇠기를 구조물에 적용하여 각 제진장치에 의한 감쇠비를 추정한 결과 매우 정교하게 예측 가능함을 알 수 있었다.

A retractable-roof spatial structure is frequently used for a stadium and sports hall. A retractable-roof spatial structure allows natural lighting, ventilation, optimal conditions for grass growth with opened roof. It can also protects users against various weather conditions and give optimal circumstances for different activities. Dynamic characteristics of a retractable-roof spatial structure is changed based on opened or closed roof condition. A tuned mass damper (TMD) is widely used to reduce seismic responses of a structure. When a TMD is properly tuned, its control performance is excellent. Opened or closed roof condition causes dynamic characteristics variation of a retractable-roof spatial structure resulting in off-tuning. This dynamic characteristics variation was investigated. Control performance of a passive TMD and a smart TMD were evaluated under off-tuning condition.

부가적인 제어장치를 사용하여 구조물 감쇠를 증가시키는 것은 건축물의 풍응답을 제어하기 위해 자주 사용되는 방법 중 하나이다. 본 연구의 목적은 TMD와 AMD의 다중모드응답 제어성능을 비교하는 것이다. 실제 AMD가 설치된 39층 건물을 사용하였으며, 이전 연구에서 시스템식별을 통해 얻어진 모드정보에 따라 수정된 수치해석모델을 사용하였다. AMD 제어력은 속도피드백, 뱅뱅 제어, LQR 알고리즘을 사용하여 결정하였다. 1차 모드의 RMS 응답을 유사한 수준으로 맞추는 조건에서 TMD와 AMD의 고차모드제 어성능을 비교하였다. 그 결과 TMD는 단일 모드에 대해서만 응답을 저감시킬 수 있었으나, AMD는 다중모드 제어가 가능함을 확인하였다.

본 연구에서는 평균입경 0.2, 0.5, 1,7㎛ 크기의 α-알루미나 분말을 이용하여 다공성 α-알루미나 지지체의 기공구조를 조절하고자 하였다. 다공성 α-알루미나 지지체는 슬립캐스팅공법을 이용하여 제조한 후 소결하였으며, 이 때 소결 온도가 지지체의 기공특성에 미치는 영향에 대하여 고찰하였다. 제조된 다공성 α-알루미나 지지체는 수은기공분석기를 이용하여 기공크기 및 기공률 등을 분석하였으며, 단일기체투과장치를 이용하여 기체 투과도를 측정하였다. 그 결과 평균입경 0.2, 0.5, 1.7㎛ 크기의 α-알루미나 분말을 이용하여 제조된 지지체는 각각 80, 130, 200㎚의 기공경을 가졌으며, CO2 단일기체에 대해 각각 1300, 1700, 5000GPU를 나타냈다.

In this study, shaking table test has been carried out for the dual frame passive control system for seismic performance verification of the proposed system. The proposed system was separated into two independent frameworks that are strength resistant core and frame structure by connecting to the damper. Moreover, the seismic performance improvement of the proposed system has been verified by comparing and analyzing the experimental results of the proposed system with an existing core system. As a result of the shaking table test, acceleration and displacement responses of dual-frame vibration control system are decreased than those of the existing strength resistant type core system. In the case of the core system, while the damage was concentrated on the column of first floor, the damage of the dual system was dispersed in each layer. The damage also was concentrated on the damper, almost no damage occurs to the structural members. It has been emphasized that installed dampers in the proposed dual system reduce the input energy of whole structure by absorbing seismic input energy, which leads overall system damage to be reduced.

본 연구에서는 평균입경 0.2, 0.5㎛ 크기의 α-알루미나 분말을 이용하여 다공성 α-알루미나 지지체의 기공구조를 조절하고자 하였다. 다공성 α-알루미나 지지체는 슬립캐스팅공법을 이용하여 제조한 후 소결하였으며, 이 때 소결 온도가 지지체의 수축률 및 소결거동 등에 미치는 영향에 대하여 고찰하였다. 제조된 다공성 α-알루미나 지지체는 수은기공분석기를 이용하여 기공크기 및 기공률 등을 분석하였으며, 단일기체투과장치를 이용하여 기체 투과도를 측정하였다. 그 결과 평균입경 0.5㎛ 크기의 α-알루미나 분말을 이용하여 제조된 지지체의 경우, 평균 입경 0.2㎛ 크기의 α-알루미나 분말을 이용하여 제조된 지지체에 비하여 기공크기가 크고 기공률이 높았으며, 기체투과도가 높을 것을 알 수 있었다.