Consumed-Power and Load Characteristics of a Tillage Operation in an Upland Field in Republic of Korea

( Jeong-gil Kim ),( Young-joo Kim ),( Jung-hun Kim ),( Beom-soo Shin ),( Ju-seok Nam ) 한국농업기계학회 2018 바이오시스템공학 Vol.43 No.2

Purpose: This study derived the consumed power and load characteristics of a tillage operation performed in an upland field located in Seomyeon, Chuncheon, Rep. Korea, where potatoes and cabbages were cultivated in two crops. Methods: A plow and rotavator were mounted on a tractor with 23.7 kW of rated power to perform the tillage operation. The work conditions were determined, considering the actual working speed of the tillage operation performed by the local farmers. The power consumption of the rear axle, engine, and power take-off (PTO), PTO torque, and tractive force were measured under each work condition. The consumed power and load characteristics were analyzed using their average values. Results: The rotary-tillage operation consumed more engine power than the plow operation for the same tractor-transmission gear condition. The PTO in the rotary-tillage operation and the rear axle in the plow operation consumed the most power. The power consumption of the engine and the PTO for the rotary-tillage operation tended to increase as the transmission gears of the tractor and the PTO became higher. In contrast, the rear-axle power consumption was insignificant. In addition, the PTO torque tended to rise as the tilling pitch increased. For the plow operation, the drawbar power and the rear axle power accounted for 68-90% of the engine power. The engine and rear axle power, drawbar power, and tractive force tended to rise as the working speed increased. Conclusions: The power consumption and load characteristics differed for the plow and rotary-tillage operations. They may also differ depending on the soil conditions. Therefore, the power consumption and load characteristics in various work environments and regions should be analyzed, and reflected in the design of tractors and working implements. The results derived from this study can be used as a reference for such designs.

호텔 직원이 지각한 권력이 집단응집성과 조직몰입에 미치는 영향

이덕원 ( Lee Duk-won ) 한국호텔리조트학회(구 한국호텔리조트카지노산학학회) 2018 호텔리조트연구 Vol.17 No.2

This study is to investigate the effect of power on group cohesivenss and organizational commitment of hotel employees and the purpose of investigating the providing directions for hotel employees to have a consistent to promote satisfaction with organizational involvement. For this study a questionnaire survey, targeting hotel employees with more than 1 year experience in domestic special first class hotel with top 10 hotels of in 2016 customer satisfaction index, was made during 8 weeks period, total 350 sheets were distributed and 312 samples were used for the empirical analysis. The according to the empirical analysis result, Power was defined by five factors derived from exploratory factor analysis: reward power, coercive power, legitimate power, expert power and referent power. two sub-factors of power, reward power had a positive(+) effect and coercive power had a negative(-) effect on group cohesivenss. Second, reward power, referent power had a positive(+) effect on organizational commitment.

가변 전력 분배 기반 다중 모드 고효율 정류기 배열

김빛찬,이다주,김지수,오준택 한국전자파학회 2022 한국전자파학회논문지 Vol.33 No.6

This study proposes a high-efficiency rectifier array with multiple power modes based on variable power distribution. The proposed rectifier array comprises of rectifier cell 1 for low-power mode, rectifier cell 2 for high-power mode, and a variable power divider. The variable power divider, composed of two branch line couplers and a variable impedance stage, determines the power-dividing ratio by controlling the variable impedance stage. If the input power is adaptively distributed in the rectifier array according to the input power, the rectifier array can maintain high efficiency over a wide input power range. The size of the proposed circuit is 67.7 mm×47.4 mm. The measurements obtained during experimentation show that proposed rectifier array has high power conversion efficiency of 80.2 % and 68.7 % in the low and high-power modes, respectively. The circuit can maintain high power conversion efficiency of over 50 % over an input power range of 4.4−28 dBm depending on the selected mode at 2.45 GHz.

소프트 파워로서 일본과 일본어에 관한 연구 -한일 대학생 앙케트를 중심으로-

양민호 한국일어일문학회 2017 日語日文學硏究 Vol.103 No.1

This study of the globalization era in which the physical boundary between nations collapsed is necessary at the present moment when mutual psychological boundaries become meaningless. This situation is gradually being restructured mainly by soft power from the power relations of the past which was influenced by military power and economic power. Therefore, in this paper, I will study soft power which was not well researched in Korea. Several results will be reported through questionnaire survey on the influence of soft power especially thought by university students in Korea and Japan. As a result, it turned out that soft power will be in charge of an important role in the future era if hard power is the indicator of the power of the country so far. Power moves according to the flow of the times. This also changes the awareness of companies in other countries we knew. Especially linguistic expression (linguistic behavior) is strongly positioned as an intermediary of soft power. 本稿は国家間の物理的な境界線が崩れた国際化時代に必要な研究である。このような状況は軍事力や経済力に左右された過去の権力関係から徐々にソフトパワーを中心に権力が再編されつつある。従って本稿では、韓国であまり研究されていなかったソフトパワーについて研究する。特に韓国と日本の大学生が考えるソフトパワーの影響力についてアンケート調査をとおしていくつかの結果を報告する。 その結果、これまでハードパワーが国の力の指標であったとしたら今後の時代ではソフトパワーが重要な役割を担当することになることが分かった。権力は時代の流れに沿って移動する。これによって我々が知っていた相手国の企業の認知度も変化する。特に言語表現(言語行動)がソフトパワーの媒介として強固に位置づけられると思う。

한국과 태국 사이의 소프트파워 협력을 위한 법제적 노력

김호 ( Kim Ho ) 한국태국학회 2024 한국태국학회논총 Vol.30 No.2

The concept of soft power is gaining significant attention in today's international relations, with various countries making concerted efforts to enhance their soft power. In particular, South Korea and Thailand are keenly focusing on strengthening soft power as a new area of collaboration, emphasizing the importance of mutual understanding and the formation of positive images in the international community. This paper aims to examine how South Korea and Thailand are enhancing their soft power and the challenges they face. Both countries are exploring ways to amplify their soft power by leveraging their unique cultures and resources. Through activities such as cultural exchanges, language courses, artistic endeavors, and sports diplomacy, they strive to foster positive perceptions on the global stage. Additionally, with a focus on enhancing soft power in the legal domain, the paper investigates how both countries are improving their soft power and analyzes potential areas for collaboration. To achieve this, the paper provides a brief introduction to the core concepts of soft power and how South Korea and Thailand are utilizing it. Subsequently, it examines the foundational aspects of their efforts to enhance soft power, delves into the efforts and challenges in the legal field, and proposes possibilities for collaboration between the two countries. It is anticipated that this analysis and proposal will serve as a crucial foundation for opening new horizons in South Korea-Thailand cooperation. Through the strengthening of soft power, both countries are expected to establish a closer collaboration, showcasing a more prominent presence in the international community. Furthermore, this paper aims to suggest avenues for effective utilization of soft power, fostering mutual benefits and solidifying the South Korea-Thailand partnership across various sectors in the global arena.

고효율 고역률 LED 조명장치용 전원공급장치

정강률(Gang-Youl Jeong) 한국정보기술학회 2018 한국정보기술학회논문지 Vol.16 No.11

This paper presents the high efficiency and high power-factor power supply for LED lighting equipment. The proposed power supply is the single-stage power structure consisted of the full-bridge diode rectifier and flyback converter, and thus the power-factor correction and output voltage regulation are performed simultaneously using only one controller IC and one power semiconductor switch. Furthermore, the proposed power supply reduces the voltage stress and switching loss of main switch using the regenerative snubber, and it improves the system efficiency using the synchronous rectifier. The applied synchronous rectifier is the new voltage-driven type and its operation and construction are simple. In this paper, the operation principle of proposed power supply is explained through the operation analyses of its power-factor correction and main power conversion parts and the operation of synchronous rectifier is described, briefly. Also, a design example of the power circuit of 40W-class prototype is shown and the operation characteristics of proposed power supply are validated through the experimental results of the implemented prototype by the designed circuit parameter.

고조파 왜곡 환경에서 향상된 역률 계측 알고리즘 개발

이현우,박영균,이진한,정상현,박철우 대한전자공학회 2016 전자공학회논문지 Vol.53 No.7

We propose a algorithm to calculate power factor of fundamental waveform in an environment where the voltage and current have been distorted by harmonics. In the proposed power factor computation algorithm, voltage and current are converted to rotating DQ reference frame, and power factor is calculated from active power and reactive power. We compare the proposed method with the conventional power factor measurement method as mathematically. In a condition that voltage and current are distorted by harmonics, the proposed method accurately measure the power factor of fundamental wave, and it is confirmed by simulation using MATLAB. If the proposed power factor measurement method is applied to an automatic power factor control system, a power factor compensation performance can be maximized in harmonic distortion environment. As a result, it is possible to reduce electricity prices, reduce line loss, increase load capacity, ensure the transmission margin capacity, and reduce the amount of power generation. 본 논문에서는 고조파로 전압과 전류가 왜곡된 상황에서 정확하게 기본파의 역률을 측정할 수 있는 방법을 제안한다. 제안한 역률 계측 방법에서는 전압과 전류를 DQ회전좌표계로 변환한 후 유효전력과 무효전력을 계산하여 역률값을 구하게 된다. 기존의 역률 계측방법과 제안한 방법을 수식적으로 비교하여 제시하고, 제안한 방법은 전압과 전류 모두 고조파 왜곡된 상황에서도 기본파의 역률을 정확하게 계측할 수 있는 것을 MATLAB을 이용한 모의실험에서 확인한다. 제안한 역률 계측방법을 자동역률제어장치에 적용할 경우 고조파 왜곡 환경에서 역률 보상 성능을 최대화 할 수 있다. 그 결과 수용가에서는 역률 개선을 통한 전기료 감소, 선로손실 감소, 부하 용량 증대 효과가 기대된다. 특히 발전 사업가 측에서는 역률 보상 성능의 향상으로 송전 여유 용량 확보와 발전량 절감이 가능하다.

Power Transition or Peaking Power Trap in Explaining the Hegemonic Competition

조해지,김우상 신아시아연구소 2023 신아세아 Vol.30 No.4

In this study we focus on the oldest IR theory that correctly predicted the current Sino-US hegemonic competition and the newest theory that suggest an imminent collision between the two superpowers. We theoretically compare Organski’s (1958) power transition theory and Brands and Beckley’s (2022) peaking power trap theory and try to empirically test key arguments of both theories. Power transition theory suggests that the key independent variables that explain the great power war are power parity between the rising challenger and the declining dominant power, and the rising challenger’s level of dissatisfaction with the existing international order. In contrast, the peaking power trap theory argues that when a rapidly rising great power, which tries to catch up with the dominant power, begins to foresee its near-future economic stagnation, and when the dominant power tries to build and strengthen its alliance system against the rising challenger, the rising power is more likely to hasten to challenge the dominant power. Results of our study indicate that power transition war is very likely when the capability of the rising challenger becomes more or less equal to that of the dominant state and that war is highly likely when the rising state is dissatisfied with the status quo. These strongly support the power transition theoretic arguments. However, these do not totally reject the peaking power trap arguments since the peaking power situation occurs when the two states are more or less equal in their national capabilities. Our study demonstrates that it is not the overtaking of power or the peaking power but the power parity situation that matters most in explaining the likelihood of the power transition war.

Power Transition Theory and the U.S. Decisions in Favor of Preventive War: A Linkage between Theory and Practice

박준혁 국방대학교 국가안전보장문제연구소 2012 The Korean Journal of Security Affairs Vol.17 No.1

Power shifts between interstate dyadic relationships are generally considered one of the most important factors affecting the preventive motivation for war. It is also a prominent cause of war in power transition theory. This theory predicts that war is likely to occur when the power of a challenger rises to parity with that of a dominant power. Based on this theory’s prediction, this paper can state two basic hypotheses as follows: (1) If power parity exists, preventive war is more likely; and (2) If power preponderance exists, preventive war is less likely. However, despite the second hypothesis indicating that war is less likely with power preponderance, the United States has often considered and launched preventive wars against middle and small powers. By critically evaluating the relevance of the above hypotheses given preventive wars launched and considered by the U.S. after World War II, this paper argues that the expected cost of war has been a crucial factor affecting the decision to engage in preventive war. In this context, this paper argues that the absence of war between the U.S. and the Soviet Union in the Cold War era was caused largely by the prohibitively high expected cost of war rather than by the preponderant power of the U.S. over the Soviet Union. This argument can also be applicable to the confrontation between the U.S. and other major and strong middle powers like China and North Korea. However, the U.S. launched preventive wars against weak middle and small powers such as Iraq and Grenada largely because the expected costs of wars in these conflicts were very low. In order to verify these arguments, this paper presents the modified version of the hypotheses of power transition theory and identifies intervening variables affecting the U.S. decisions in favor of preventive war.

파워 유형과 파트너십 연계를 통한 공급사슬관리 개선방안 모색

정대현,박광오 대한경영정보학회 2016 경영과 정보연구 Vol.35 No.3

SCM 성과 극대화를 달성하기 위한 전제조건으로 파트너십 관계의 구축 및 유지가 중요하다. 기업 간 SCM 성과 제고를 위한 지속적인 노력에도 불구하고, 기업 간 힘의 불균형에 따라 발생할 수 있는 비효율적인 낭비 요소가 만연해 있다. 이러한 협업의 걸림돌이 되는 요소가 파워(Power)의 한 속성이다. 따라서 본 연구의 목적은 파워유형의 속성을 파악하고 파트너십 향상을 통해 공급사슬관리의 개선방안을 모색하고자 하였다. 선행연구를 통해 파워의 원천을 크게 구속적 파워와 비구속적 파워로 분류하여, 구속적 파워의 종류로는 행동 강제성, 구속적 보상, 관계 합법성으로 구분하였으며, 비구속적 파워의 종류로는 업무 전문성, 정보 우위성, 가치 준거성으로 구분하여 살펴보고자 한다. 따라서 파워의 유형을 살펴보고 파트너십 주요 변인인 신뢰 및 몰입에 미치는 영향과 협업 및 SCM 성과로 이어지는 인과관계를 밝혀 보았으며 구체적인 연구 결과는 다음과 같다. 첫째, 구속적 파워는 신뢰에 유의한 영향을 미치지 못하였다. 그러나 구속적 파워가 몰입에는 정(+)의 유의한 영향을 미치는 것으로 나타났다. 둘째, 비구속적 파워는 신뢰와 몰입 모두에 유의한 영향을 보였다. 총효과 분석결과 역시 비구속적 파워는 협업 및 SCM 성과에 간접영향을 미치는 것으로 나타났다. 셋째, 신뢰와 몰입은 모두 협업에 유의한 영향을 미치는 것으로 나타났다. 조직 간 관계이론 중 사회교환이론 및 거래비용이론 측면에서 살펴본 신뢰, 몰입, 협업의 SCM 성과로 이어질 수 있으며 더불어 파워의 속성별 연계가 유의미한 결과로 이어지는 것을 확인할 수 있었다. 넷째, 신뢰와 협업은 SCM 성과에 유의한 영향을 미치는 것으로 나타났다. 그러나 몰입은 직접적으로 SCM 성과에는 영향을 미치지 못하였다. 다만 협업을 통한 SCM 성과에는 간접적으로 유의한 영향을 미치는 것으로 나타났다. 기업들은 파워의 원천, 불균형, 결과들에 대한 이해를 포함한 공급사슬 내 파트너기업에 대한 충분한 이해와 인식을 하여야 하는데, 이러한 파워의 적절한 사용은 공급사슬 구성원 간 협력관계를 공고히 구축하고 이에 따라 공급사슬 성과의 향상과 구성원 만족을 유도할 수 있을 것이다. It is required to derive various conclusions by identifying the type of power and the relationship between SCMs and presenting practical implications. Thus, we can identify the differential effects of each type of power on SCM performance. We can contribute to develop the practical implications at more sophisticated multi-dimension by comparing results of this study with various SCM theories. Through previous studies, the source of power is largely divided into binding power and non-binding power. Binding power is classified into behavior coercion, binding reward and relationship legitimacy. Non-binding power is classified into work expertise, information superiority and value compliance. Enterprises should fully understand and recognize partners within supply chains including understanding of the source of power, imbalance and results. Thus, we look into types of power and effects on trust and commitment, and identify a causal relationship leading to collaboration and SCM performance. Specific research results are as follows. First, the binding power did not give a significant effect to the trust. However, the binding power gave a positively(+) significant effect to the commitment. Second, non-binding power showed a significant effect on both trust and commitment. As a result of analysis on total effects, it was shown that non-binding power gave indirect effects to collaboration and SCM performance. Third, it was shown that both trust and commitment significantly affected collaboration. From the perspectives of social exchange theory and trading cost theory among inter-organizational relationship theory, it may lead to SCM performance of trust, commitment and collaboration. Moreover, it was found that association of each attribute of power led to the significant result. Fourth, it was shown that trust and collaboration significantly affected SCM performance. However, commitment did not directly affect SCM performance, but it indirectly significantly affected SCM performance through collaboration. Proper use of this power can firmly build partnerships between members of the supply chain and induce the improvement on supply chain performance and satisfaction of members.