• Journal of Korea Water Resources Association
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• v.51 no.10
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• pp.929-939
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• 2018

In North Korea, hydropower which occupies about 63% of power generation is a major electric power source, and North Korea has many advantages in the geographical for developing hydroelectric power. In this study, Information on the basin and dam capacity for 33 potential development site of hydroelectric dam was analyzed using DEM, and potential annual power generation was estimated by applying results of long-term runoff simulation with MWSWAT model for recent 30-year. The potential annual power generation at 33 dam was estimated to be about 28% of the current hydroelectric power in North Korea. In addition, a priority of dam development in each province was assessed by estimating the scale of an industry and prospecting the population change in the future. And a priority for dam development within the province was estimated based on the dam capacity and the potential annual power generation. The priority of each province was ranked in order of Pyeongannamdo, Hamgyungnamdo, Hamgyungbukdo, Hwanghaebukdo, Pyeonganbukdo, Jagangdo, Ryanggangdo, Hwanghaenamdo, and Gangwondo. The results of this study can be used as an initial review data for advancing to hydropower development project in North Korea.

• Journal of Korea Water Resources Association
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• v.53 no.8
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• pp.617-626
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• 2020

This study investigates changes of bifurcation discharge ratio, flow velocity distributions and characteristics of separation zone due to variation of bifurcation angle by using TELEMAC-2D model. When the bifurcation angle is reduced from 90° to 45° without changing the boundary conditions, the bifurcation discharge ratio increased by 1.5 times from 0.523 to 0.785 because of increasing the radius of curvatures, the inertia force of the downstream flow, and the pressure gradient by the downstream boundary conditions. The bifurcation discharge ratio increases non-linearly whenever the bifurcation angle decreases by 15° intervals from 90° to 45° in flow with the upstream Froude number of 0.45 to 0.74. In flow with a maximum Froude number of 0.74, the rate of increase for bifurcation discharge ratio is 31.1% and the minimum value. When the Froude number is 0.58, the bifurcation discharge ratio is 0.7 or less, and the maximum rate of increase for that ratio is 53.5%. As the upstream Froude number decreases less than 0.58, the bifurcation discharge ratio exceeds 0.7, and the rate of increase decreases. When the upstream Froude number is 0.4 higher, the dimensionless width and length changing ratio of the separation zone are about 2.56 and 5.5 times higher than in 0.4 or less.

• Journal of Korea Water Resources Association
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• v.38 no.8 s.157
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• pp.675-689
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• 2005

In this paper, it was analyzed the variation of hydraulic characteristics through changing discharge at main channel and lateral channel and state of hydraulic structure at the natural channel junction by experiment. The experimental area is chosen at the channel junction of Nam-Han river and Pyeongchang river. The scale of the experiment is 1/200 in horizontal, and 1/66.7 in vortical, so the distoration rate is 3. From the experiment, the reduction effect of the water level is $12\%$ in the case of removing intank dam, and $5\%$ at the hydro-electronic dam removing case. Furthermore, in the case of two hydraulic structures removing, the reduction effect of water level is $18\%$ at the channel junction. Also, the stagnation zone, which is cased diminution of the channel at the junction, is decreasing through removing the structures.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.11
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• pp.846-850
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• 2009

Recently, wireless sensor networks have found their way into a wide variety of applications and systems with vastly varying requirements and characteristics such as environmental monitoring, smart spaces, medical applications, and precision agriculture. The sensor nodes are battery powered. Therefore, the energy is the most precious resource of a wireless sensor network since periodically replacing the battery of the nodes in large scale deployments is infeasible. Energy efficient mechanisms for gathering sensor readings are indispensable to prolong the lifetime of a sensor network as long as possible. There are two energy-efficient approaches to prolong the network lifetime in sensor networks. One is the compression scheme to reduce the size of sensor readings. When the communication conflict is occurred between two sensor nodes, the sender must try to retransmit its reading. The other is the MAC protocol to prevent the communication conflict. In this paper, we propose a novel approaches to reduce the size of the sensor readings in the MAC layer. The proposed scheme compresses sensor readings by allocating the time slots of the TDMA schedule to them dynamically. We also present a mathematical model to predict latency from collecting the sensor readings as the compression ratio is changed. In the simulation result, our proposed scheme reduces the communication cost by about 52% over the existing scheme.

• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.45-53
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• 1987

The purpose of this study was to evaluate the tensile bond strength between composite resin and the human enamel. Three composite resin systems, two chemical (Clearfil Posterior, and Clearfil Posterior-3) and one light cure (Photo Clearfil-A), used with and without an intermediate resin (clearfil bonding agent), were evaluated under different amounts of load (10g, 200g and 200g for a moment) for in vitro tensile bond strength to acid-eched human enamel. Clinically intact buccal or lingual surfaces of 144 freshly extracted human permanent molars, embedded in acrylic were flattened with No #600 carborundum discs. Samples were randomly assigned to the different materials and treatments using a table of random numbers. Eight samples were thus prepared for each group(Table 2) these surfaces were etched with an acid etchant (Kurarey Co. Japan) in a mode of etching for 30 seconds, washing for 15 seconds, and drying for 30-seconds. During the polymerization of composite resin on the acid-etched enamel surfaces with and without bonding agent 10-gram, 200 gram and temporary 200 gram of load were applied. The specimens were stored in 50% relation humidity at $37^{\circ}C$ for 24 hours before testing. An universal Testing machine (Intesco model No. 2010, Tokyo, Japan) was used to apply tensile loads in the vertical directed (fig 5), and the force required for separation was recorded with a cross head speed of 0.25 mm/min and 20 kg in full scale. The results were as follow: 1. The tensile bond strength was much greater in applying a bonding agent than in not doing that. 2. The tensile bond strength of chemical cure composite resin was higher than that of light cure composite resin with applying on bonding agent on the acid-etched enamel. 3. In case of not applying a bonding agents on the acid-etching enamel, the highest tensile bond strength under 200 gram of load was measured in light cure composite resin. 4. The tensile bond strength under 200-gram of load has no relation with applying the bonding agent. 5. Under the load of 10-gram, There was significant difference in tensile bond strength as applying the bonding agent.

• Journal of Distribution Science
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• v.13 no.1
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• pp.35-46
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• 2015

Purpose - This paper attempted to investigate the relationships among the perception of job insecurity and organizational effectiveness, and it examines these relationships while considering the moderating effect of trust in the manager and self-efficacy. Job insecurity is an independent variable, organizational effectiveness aspects (job satisfaction, organizational commitment, and turnover intention) are dependent variables, and trust and self-efficacy are moderators. Research design, data, and methodology - Regression analysis was used to verify the effects. The measurement items were already deemed as reliable and valid in the previous study, but for this purpose, some modifications were made. To examine the model, this study relied on the samples chosen from Korean employees in the six franchise business firms. The survey was conducted on 288 workers. Each question is based on a 5-point Likert type scale. The data were analyzed using SPSS 18.0. Results - The results of the study are summarized as follows. First, job insecurity has an influence on organizational effectiveness aspects (negatively on job satisfaction, negatively on organizational commitment, and positively on turnover intention). Second, analyzing the moderating effect of trust, trust in manager is mediated between job insecurity and organizational effectiveness aspects (on organizational commitment and on turnover intention). However, employees' trust in manager had no significant moderating effect on the job insecurity-job satisfaction relationship. Third, self-efficacy is mediated between job insecurity and organizational effectiveness aspects (on job satisfaction, on organizational commitment, and on turnover intention). Conclusions - First, it is necessary to be aware of the seriousness of employees' job insecurity in franchise firms, which have played a pivotal role in national economic growth, and to create a detailed plan for reducing insecurity and actively implementing it. To this end, the franchise companies should implement efficiency efforts such as obtaining an appropriate capacity of equipped personnel and a training program. Second, there are moderating effects of self-efficacy and trust in the relationship between job insecurity and organizational effectiveness. Depending on business conditions, stability and instability can only be experienced in the organizations of franchise companies. This can give rise to instability in employment. Therefore, it is necessary to develop and utilize a system that can be minimized with a change in the new awareness of employment instability. After all, a good leader (manager) must accumulate personal trust and build up a core competence that is necessary to become competent in the field himself. Even if you lack the material resources to improve performance, if the leader with the core competencies (e.g., technical/management /organization/marketing/design) can gain the trust of the supervisor, you can get a good organizational performance. Therefore, you should foster a healthy organizational culture through education such as leadership training and employee training to be built on trust between the leaders and the employees. In addition, you need to focus on HRD&M training in order to increase the self-efficacy of the supervisor.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.6
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• pp.782-792
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• 1999

효과적인 ATM 망의 관리는 연결 지향 환경, 다양한 서비스 등급, 대규모 트래픽, 가상 망 구성 그리고 여러가지 트래픽 유형 등과 같은 다양한 ATM 특성을 다룰 수 있어야만 한다. 이를 위해 ATM 포럼에서는 ATM 장치, 사설망, 공중망 및 그들간의 상호작용을 지원하기 위한 ATM 망 관리 참조 모델을 정의하였으며, 그 중 하나가 서로 다른 판매자로부터의 ATM 장비들간의 상호동작성을 보장하기 위해 SNMP 기반 망 관리 프로토콜을 통해 상호 연결된 인터페이스를 관리할 수 있도록 정의된 통합 지역 관리 인터페이스(ILMI) 프로토콜이다. ILMI의 목적은 두 인접한 ATM 장치로 하여금 그들 간에 공통의 ATM 링크에 대한 동작 파라메타를 자동적으로 구성할 수 있도록 함으로서, 관리자에 의해 수동 구성이 아닌 ATM 장치 상호간의 플러그 앤 플러그 기능을 지원하는데 있다. 본 논문에서는 이러한 ILMI 기술을 바탕으로 공중망 ATM 교환기에 연결된 가입자의 물리 인터페이스, ATM 계층 인터페이스, VPC 및 VCC의 구성 및 상태 정보를 효율적으로 관리하며, 가입자 시스템의 ATM 주소를 자동으로 등록, 관리할 수 있도록 하는 가입자 인터페이스 관리 시스템(SIMS)을 설계하고, 구현하였다. Abstract An effective ATM management must address the various features of ATM such as connection-oriented environment, varying class of service, large scale traffic, virtual network configurations and, and multiple traffic types. For this, ATM network management reference model defined by ATM Forum describes the various types of network management needed to support ATM devices, private networks, public networks, and the interaction between them. One of these types is Integrated Local Management Interface (ILMI) defined to manage interconnected interface through SNMP-based network management protocol for ensuring the interoperability of ATM devices from different vendors. The purpose of ILMI is to enable two adjacent ATM devices to automatically configure the operation parameters of the common ATM link between them and then to provide a Plug and Plug function to any ATM devices with not a passive configuration by manager but a automatic configuration. This paper design and implement a Subscriber Interface Management System (SIMS) which provide automatic registration and management of ATM address of subscriber system and efficiently manages physical interface of subscriber who is connected to public ATM switch, ATM layer interface, configuration information and status information of VPC and VCC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.422-429
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• 2007

Location awareness is one of the key functionalities to build an U-city. Recently, many of works of the location-aware systems are emerging to commercially apply to on-going large-scale apartment complex based on U-city. As dwellers or cars being attached with active tags are moving in the U-city complex, the active tags periodically broadcast their own identifiers and receivers fixed along the street or in building use those information to calculate location of them. There are several issues to be considered for such an environment. The first is that the number of active tags operating in the same region are large as much as tens of thousands, and the second is that the active tags should be alive without change of batteries more than a year, hence low power consumption is very important. In this paper we propose i) a new architecture for location-aware system considering such issues, ii) technical issues to implement it using active tags, and iii) a mathematical analytic model to investigate overall performance and verify it by comparing with actual experimental results. Through the analysis we can show the theoretical boundary of the lowest packet loss rate and the maximum number of tags with acceptable performance for the systems based on active tags. The results can be applied to practical design of location-based systems of U-City projects.

• Journal of agriculture & life science
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• v.44 no.6
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• pp.171-182
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• 2010

Water demand and resource at a watershed scale were investigated to prepare for long-term water planning of the Namgang sub-basin. The quantity of water resource was defined as average annual runoff by a simple Tank model with three serial tanks, and water demand for public, industrial, agricultural and the other uses was determined using the per-unit method employed in the Water Vision 2020, the Ministry of Construction and Transportation. The results showed that total amount of water resources in the Namgang sub-basin was estimated as about $935,414{\times}10^{3}m^3/yr$ for a 10-year period from 2000 to 2009 and the water withdrawals in public, industrial, agricultural and other sector were derived as $105,493{\times}10^{3}m^3/yr$, $32,686{\times}10^{3}m^3/yr$, $243,194{\times}10^{3}m^3/yr$, and $81,615{\times}10^{3}\;m^3m^3/yr$, respectively. In addition, the Namgaram Inno-city project could increase the overall water demand by $17,156{\times}10^{3}\;mm^3/yr$ due to the population influx.

• The Journal of the Korea Contents Association
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• v.19 no.10
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• pp.607-619
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• 2019

This study used Natural Monument water spiders and their habitats as educational contents, so those students could have a scientific literacy and the beautiful memories of Eundaeri's marshes through developing a virtual fieldwork courses (VFC) and observing the ecology of water spiders. In order to develop the program, the 2015 revised national curriculum and its textbooks were analyzed. In accordance with the STEAM model, we developed teaching-learning materials for 7 classes. Students produced 3D panorama virtual fieldwork courses (PVFC) about water spider by team-based cooperative learning, enabling them to emotionally experience the meaning and value of water spiders. A panel of six education experts verified the validity of the program and found it to be fairly valid at 4.24 (CVI = .88) on the 5-point Likert scale. In order to confirm the suitability of the program, students in the middle school science clubs participated in pilot testing camp. Their average classes satisfaction was 4.24 and students were very satisfied with the usefulness of the program, the fresh learning contents, and the suitability of the convergence education class. This study could contribute to convergence education related to ecology and virtual reality for adolescents.