• 한국기계가공학회지
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• 제20권11호
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• pp.115-120
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• 2021

In this study, cigarettes, which are an essential element in the production of tobacco, are generally not cylindrical. The main materials used for cigarettes are generally hemp and pulp. For the production of cylindrical cigarettes, the cigarettes or cylinders are mounted via gluing. This adhesive is a vinyl acetate emulsion, a high-temperature melt adhesive, and is adhered in a cylindrical shape immediately after being linearly applied to the inner surface of the paper roll or a local part. These adhesives are greatly affected by the atmospheric temperature of the manufacturing space in summer and winter. In the summer, even if the adhesive is temporarily adhered, the coagulation time of the adhesive is long, and problems such as deterioration of the adhesive state occur. in the winter, there is a problem that the temperature of the manufacturing space is low and the adhesive force of the adhesive is poor, resulting in defective adhesive products. In order to solve these problems, another heat transfer device is utilized to cure the remaining adhesive to ensure higher adhesiveness.

• Design & Manufacturing
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• 제18권2호
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• pp.41-50
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• 2024

In this study, experimental design methods were used to derive optimal process conditions for improving the thickness uniformity of a 0.40 mm, 3.5 inch light guide panel. Process mapping and expert group analysis were used to identify factors that influence the thickness of injection molded products. The key factors identified were mold temperature, mold temperature, injection speed, packing pressure, packing time, clamp force, and flash time. Considering the resin manufacturer's recommended process conditions and the process conditions for similar light guide plates, a three-level range was selected for the identified influencing factors. L27 orthogonal array process conditions were generated using the Taguchi method. Injection molding was performed using these L27 orthogonal array to mold the 3.5 inch light guide plates. Thickness measurements were then taken, and the results were analyzed using the signal-to-noise ratio to maximize the CpK value, leading to the determination of the optimal process conditions. The thickness uniformity of the product was analyzed by applying the derived optimum process conditions. The results showed a 97.5% improvement in the Cpk value of 3.22 compared to the process conditions used for similar light guide plates.

• Journal of Advanced Marine Engineering and Technology
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• 제39권7호
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• pp.709-715
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• 2015

일반적인 무인잠수정과는 달리 수중 글라이더는 별도의 추진체를 가지지 않고 부력과 중력의 차이에 의해서 추진력을 얻게 된다. 추진력을 얻기 위해 부력을 조절하게 되며, 부력의 변화는 부력엔진을 이용하며 수중 글라이더의 체적을 변화시킨다. 또한, 수중 글라이더의 자세를 제어하기 위해 별도의 방향타를 사용하지 않고 내부의 자세제어기를 이용하여 내부 이동질량의 위치변화를 이용한다. 내부 이동질량의 위치변화에 의한 질량중심과 질량관성모멘트의 변화가 발생하게 되며 이로 인해 수중 글라이더의 자세가 변화하게 된다. 본 논문에서는 수중 글라이더의 기구학적 특성과 운동특성을 반영한 비선형 6자유도 운동방정식을 유도하고 이를 이용한 운동 시뮬레이션을 수행하였다. 자세제어기를 이용하여 수중 글라이더의 종동요각과 횡동요각 제어 운동 시뮬레이션을 수행하였으며, 종동요각과 횡동요각 제어에 따른 수중 글라이더의 운동특성을 해석하였다.

• 무역상무연구
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• 제6권
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• pp.11-51
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• 1993

This study is focused on the problems and the suggestions of proper ideas for solving them which are arisen from appling CIF, Incoterms 1990 into the contract of sale after reviewing of the contents of traditional CIF contract and the main changes of CIF, Incoterms 1990. This study summerized as follows: First, when the seller provide the buyer with non-negotiable sea waybill or inland waterway document instead of negotiable bill of lading, it is my feeling that the essence of symbolic delivery in traditional CIF contract is fading. And if the buyer has paid for the goods in advance, or a bank wishes to use the goods as security for a loan extended to the buyer, it is not sufficient that the buyer or the bank be named as consignee in a non-negotiable document. This is true because the seller by new instractions to the carrier could replace the named consignee with someone else. To protect the buyer or the bank it is therefore necessary that the original instructions from the seller to the carrier to deliver the goods to the named consignee be irrevocable. Second, CIF term can only be used for sea and inland waterway transport. When the ship's rail serves no practical purposes such as in the case of roll-on/roll-off or container traffic, CIP term instead of CIF term is more appropriate to use. Third, the EDI method still contains many legal and technical problems to be solved in order to be used thoroughly' in the international sale of goods. Therefore, the parties wishing to replace the traditional paper-based trade documents by electronic messages must exchange the agreement on EDI each other in order to prevent and sol ye unexpected problems. Forth, it may be that the goods are to be carried in bulk without such marking or naming of consignee as would amount to appropriation. Then the risk will not pass until effective appropriation has been made. Therefore, the seller needs to appropriate by issuing of separate bills of lading or delivery orders for parts of the bulk cargo. And in case the goods are bought while they are carried at sea, some problems on the passing of risk would arise. One possibility is that the buyer might have to assume risks which have already occured at the time when the contract of sale is entered into force. The other possibility would be to let the pissing of the risk concide with the time when the contract of sale is concluded. The parties are advised to ascertain the applicable law and any solution which might follow there form. Finally, Incoterms are restricted to deal with the main principles for the division of functions, costs and risks between the parties and the rest is left to their individual contract as supplemented by the custom of the trade, the individual terms of the contract of sale and the applicable law. Thus, the parties are advised to ascertain the applicable law on their individual contract of sale in order to solve the problems on the transfer of property, the remedy and so on.

• 한국항공우주학회지
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• 제32권10호
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• pp.118-126
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• 2004

이산와류법(discrete vortex method)을 이용하여 진통하는 평판들로부터 추력발생을 연구하였다. 평판들과 후류들은 이산와류로 나타내었다. 진동하는 평판들 사이의 복잡한 공력상호작용을 정확히 계산하기 위하여 와핵모델(vortex core model)과 와핵첨가법(vortex core addition scheme)을 사용하였다. 단일 평판이 히빙진동을 할 경우 나타나는 후류를 계산하여 기존의 유동가시화 결과와 비교하였다. 피칭진동 시 평판에서 발생하는 후류형상이 평판들의 추진 특성에 미치는 영향을 조사하였다. 3가지 방식(1. 하나의 평판은 고정 다른 평판은 진동, 2. 두개의 평판이 같은 위상으로 진동, 3. 두개의 평판이 반대의 위상으로 진동)으로 진동하는 평판들의 추진특성을 계산하였다. 반대의 위상으로 진통하는 평판이 가장 큰 추진력을 보였다.

• 한국해안해양공학회지
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• 제3권2호
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• pp.92-99
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• 1991

해상에 계류된 부유체는 입사하는 파도에 의해 선형항인 파랑하중과 함께 2차항인 표류력을 받는다. 2차항의 표류력은 자유표면조건의 비선형성에 의해 서로 유사한 주파수를 갖는 2개의 선형 성분파간의 상호작용으로 발생하는 장주기 성분을 포함하고 있다. 대개의 계류계의 수평 인장력은 관성력항에 비해 아주 작은 양이고, 따라서 계류계의 설치로 나타나는 부유체의 수평운동 고유주기는 장주기이므로 때로는 공진이 일어나게 된다. 이렇게 야기된 대진폭운동은 작업조건을 악화시키는 것은 물론 계류계에 심각한 손상을 줄 수 있다. 부유체의 계류계로 최근 관심을 모으고 있는 Turret 계류계의 설계에도 이러한 장주기 표류력에 대한 고려와 함께 풍향성이 있는(weathervaning) 천이운동시 Roller Bearing에 걸리는 수평하중에 대한 해석이 필수적이다. 본 논문에서는 불규칙파중에 계류된 부유체에 작용하는 장주기 표류력을 2차 전달함수를 사용하여 계산한 뒤 장주기 표류력에 의한 전후동요를 시간기억 효과를 고려하여 시뮬레이션하였다. 계류계로는 분산된(spread) Turret형 계류계를 대상으로 하였으며 계류계의 수평인장계수를 매시간 단계마다 계산하는 방법으로 비선형성을 고려하였다.

• 한국생산제조학회지
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• 제21권4호
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• pp.683-690
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• 2012

In this work, the semi-active control of a large-sized bus suspension system with an MR damper was studied. An MR damper model that can aptly describe the hysteretic characteristics of an MR damper was adopted. Parameter values of the MR damper model were suitably modified by considering the maximum damping force of a passive damper used in the suspension system of a real large-sized bus. In addition, a fuzzy logic controller was developed for semi-active control of a suspension system with an MR damper. The vertical acceleration at the attachment point of the MR damper and the relative velocity between sprung and unsprung masses were used as input variables, while voltage was used as the output variable. Straight-ahead driving simulations were performed on a road with a random road profile and on a flat road with a bump. In straight-ahead driving simulations, the vertical acceleration and pitch angle were measured to compare the riding performance of a suspension system with a passive damper with that of a suspension with an MR damper. In addition, a single lane change simulation was performed. In the simulation, the lateral acceleration and roll angle were measured in order to compare the handling performance of a suspension system using a passive damper with that of a suspension system using an MR damper.

• 한국항해학회지
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• 제25권2호
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• pp.195-205
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• 2001

중화인민공화국해상법은 1993년 7월 1일 시행되어서 이미 7년 이상이 지났는바, 그간 중국 해상운송관계 또는 해난사고의 분쟁을 조율하는데 있어서 큰 역할을 해 왔다. 그러나 중국 해상법이 입법 당시부터 타당하지 못한 부분이나 시행과정에서 드러난 합리적이지 못한 부분에 대한 개정은 불가피한 것이다. 따라서 본 논문에서는 중국 해상법 중 인도지연의 의의, 인도지연으로 인한 운송인의 법적 책임, 인도지연에 대한 운송인의 면책사유와 책임제한 그리고 운송인에 대한 손해배상 청구절차에 관한 규정에 대하여 대략적인 고찰을 하고 아울러 중국해상법 타당성 여부에 대하여 검토하고자 한다.

• Wind and Structures
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• 제23권2호
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• pp.127-142
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• 2016

Aerodynamic effects, such as drag force and flow-induced vibration (FIV), on civil engineering structures can be minimized by optimally modifying the structure shape. This work investigates the turbulent wake of a square prism with its faces modified into a sinusoidal wave along the spanwise direction using three-dimensional large eddy simulation (LES) and particle image velocimetry (PIV) techniques at Reynolds number $Re_{Dm}$ = 16,500-22,000, based on the nominal width ($D_m$) of the prism and free-stream velocity ($U_{\infty}$). Two arrangements are considered: (i) the top and bottom faces of the prism are shaped into the sinusoidal waves (termed as WSP-A), and (ii) the front and rear faces are modified into the sinusoidal waves (WSP-B). The sinusoidal waves have a wavelength of $6D_m$ and an amplitude of $0.15D_m$. It has been found that the wavy faces lead to more three-dimensional free shear layers in the near wake than the flat faces (smooth square prism). As a result, the roll-up of shear layers is postponed. Furthermore, the near-wake vortical structures exhibit dominant periodic variations along the spanwise direction; the minimum (i.e., saddle) and maximum (i.e., node) cross-sections of the modified prisms have narrow and wide wakes, respectively. The wake recirculation bubble of the modified prism is wider and longer, compared with its smooth counterpart, thus resulting in a significant drag reduction and fluctuating lift suppression (up to 8.7% and 78.2%, respectively, for the case of WSP-A). Multiple dominant frequencies of vortex shedding, which are distinct from that of the smooth prism, are detected in the near wake of the wavy prisms. The present study may shed light on the understanding of the underlying physical mechanisms of FIV control, in terms of passive modification of the bluff-body shape.

• 한국항해항만학회지
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• 제28권5호
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• pp.347-352
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• 2004

파도에 의한 힘과 모멘트는 운항하는 선박에 운동을 발생시킨다. 이러한 운동은 승무원의 작업 능률 저하, 화물의 안전 및 승선감 등에 영향을 주게 되어 안전 운항 저해 요소가 되므로 파도에 의학 운동이 큰 선박들은 자세제어장비(anti-rolling devices)의 장착이 요구된다. 본 연구에서는 수 능동의 이동질량안정기(moving weight stabilizer), 감요탱크(anti-rolling tank), 핀스태빌라이저(fin stabilizer)와 같은 자세제어장비의 동적 거동을 수학적으로 모델링 하였다 기존에는 자세제어장비의 운동을 선박의 횡동요에만 고려한 반면, 본 연구에서는 선박의 6자유도 운동을 모두 고려하여 복합운동방정식을 정립하였다. 마지막으로 자세제어장비를 장착한 선박의 파중 운동 계산 프로그램을 작성하여 시뮬레이션을 수행하였다.